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  • 1995-1999  (15.826)
  • 1955-1959  (3.775)
  • Polymer and Materials Science  (18.770)
  • Atomic, Molecular and Optical Physics  (830)
  • Nuclear reactions
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Schlagwörter
  • 201
    Digitale Medien
    Digitale Medien
    Surface functionalization of polymer latex particles. III. A convenient method of producing ultrafine poly(methylstyrene) latexes with aldehyde groups on the surface (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2103-2109 
    Details
    ISSN: 0887-624X
    Schlagwort(e): functionalization of polymer latexes ; poly(methylstyrene) ; catalytic oxidation ; ultrafine particles ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A convenient method of preparing ultrafine poly(methylstyrene) (PMS) latex particles with aldehyde groups on the surface is developed. PMS latexes in the size range 33-81 nm were prepared via microemulsion polymerization, using cetyltrimethylammonium bromide (CTAB) as surfactant. The surface of the PMS latexes was oxidized in the presence of tert-butyl hydroperoxide catalyzed by copper(II) chloride. As the degree of oxidation increased up to 6 h, the amounts of aldehyde group increased. Bigger particles were found to have a slightly higher rate of oxidation than small ones under the same oxidation conditions. The particle size underwent little change during oxidation; thus, the amounts of functional groups and the particle size could be controlled concurrently. Dialysis study of the oxidized PMS microlatexes indicated that the instability of highly oxidized PMS microlatexes was caused by the reduction of total surface charge density due to the presence of carboxylic acid groups. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2103-2109, 1998
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 202
    Digitale Medien
    Digitale Medien
    New synthetic route for weak base anion exchangers based on crosslinked polystyrene (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2151-2154 
    Details
    ISSN: 0887-624X
    Schlagwort(e): anion exchangers ; crosslinked polystyrene ; Friedel-Crafts acetylation ; Mannich amination ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: No abstract.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 203
    Digitale Medien
    Digitale Medien
    Helix-sense-selective copolymerization of phenyl[bis(2-pyridyl)]methyl methacrylate, diphenyl(2-pyridyl)methyl methacrylate and triphenylmethyl methacrylate with chiral anionic initiators (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2127-2133 
    Details
    ISSN: 0887-624X
    Schlagwort(e): phenyl[bis(2-pyridyl)]methyl methacrylate ; (S)-(+)-1-(2-pyrrolidinylmethyl)pyridine ; anionic asymmetric copolymerization ; optically active copolymer ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Optically active poly[triphenylmethyl methacrylate-co-phenyl[bis(2-pyridyl)]methyl methacrylate] (poly[TrMA-co-PB2PyMA], poly[diphenyl(2-pyridyl)methyl methacrylate-co-phenyl[bis(2-pyridyl)]methyl methacrylate] (poly[D2PyMA-co-PB2PyMA]), and poly[triphenylmethyl methacrylate-co-diphenyl(2-pyridyl)-methyl methacrylate] (poly[TrMA-co-D2PyMA]) were prepared by helix-sense-selective copolymerization with complexes of organolithium with (-)-sparteine [(-)Sp],(S, S)-(+)- and (R, R)-(-)-2,3-dimethoxy-1,4-bis(dimethylamino)butane [(+)- and (-)DDB], and (S)-(+)-2-(1-pyrrolidinylmethyl)pyridine [(+)PMP] as anionic initiators in toluene at low temperature. The copolymers obtained with (-)Sp and (+)DDB or (-)DDB complexes of organolithium showed low optical activity, but to [(+)PMP] complex with N,N′-diphenyleneamine monolithium amide [(+)PMP-DPEDA-Li)] was effective in synthesizing copolymers of high optical rotation ([α]25D about +320 to + 370°) which were comparable to those of corresponding homopolymers with one-handed helical structure. The optical rotations of poly[TrMA-co-PB2PyMA] and poly[TrMA-co-D2PyMA] were much more stable than that of poly(D2PyMA) or poly(PB2PyMA) in a solution of CHCl3-2,2,2-trifluoroethanol (10 : 1, v/v) at 25°C, but optical rotation of poly[D2PyMA-co-PB2PyMA] slowly decreased with time in the same conditions. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2127-2133, 1998
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 204
    Digitale Medien
    Digitale Medien
    Preparation of poly(aryleneethynylene)-type copolymers containing flexible linking methylene units. Optical properties of the copolymers suggesting occurrence of energy transfer between π-conjugated local units (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2201-2207 
    Details
    ISSN: 0887-624X
    Schlagwort(e): poly(aryleneethynylene) ; palladium-catalyzed ; copolymer ; optical properties ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Palladium-catalyzed polycondensation between 2,5-diiodo-3-hexylthiophene I-Th(Hex)-I with mixtures of p-diethynylbenzene HC≡C - Ph - C≡CH and α,ω-diethynylalkane HC≡C(CH2)lC≡CH (l = 3 or 8) gives poly(aryleneethynylene) PAE-type copolymers [C≡C(CH2)lC≡C - Th(Hex)]m[C≡C - Ph - C≡C - Th(Hex)]n containing the methylene unit. The copolymers have a molecular weight (Mn) of about 1.2 × 104 as determined by GPC (polystyrene standard) and are considered to possess essentially a random sequences in view of the  - C≡C(CH2)lC≡C -  and  - C≡C - Ph - C≡C -  units as judged from their UV-visible spectra. By the incorporation of the (CH2)l unit, the λmax position of the corresponding PAE homopolymer [C≡C - Ph - C≡C - Th(Hex)]n is shifted to a shorter wavelength. However, the copolymers give rise to a photoluminescence PL peak essentially agreeing with a PL peak of the homopolymer, suggesting occurrence of energy transfer in the copolymer. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2201-2207, 1998
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 205
    Digitale Medien
    Digitale Medien
    Photolysis of a fluorinated polymer film by vacuum ultraviolet radiation (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2215-2222 
    Details
    ISSN: 0887-624X
    Schlagwort(e): fluorinated polymer ; vacuum ultraviolet ; Xe lamp ; photolysis ; photo-oxidation ; surface modification ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: We studied the photolysis of a fluoroethylene-fluoropropylene copolymer (FEP) film by vacuum ultraviolet (VUV) radiation from a resonance Xe lamp at a wavelength of 147 nm and air pressures of 0.05 and 2.5 Torr. The chemical changes in the FEP surface layer were investigated by Fourier-transform infrared spectroscopy with attenuated total reflection attachment and X-ray photoelectron spectroscopy. Double bonds were found to be the main product in the case of VUV treatment at 0.05 Torr, while photo-oxidation of FEP occurred predominantly by VUV treatment at 2.5 Torr under formation of the  - CF2C(O)F group. This oxygen-containing group was more effectively formed in the FEP surface layer by VUV photo-oxidation than by conventional surface oxidation techniques such as treatments by plasma and corona discharge and ozone. Storage of the VUV-treated polymers in air at 50% relative humidity resulted in hydrolysis of  - CF2C(O)F to the  - CF2COOH group. Substantial improvement of the film wettability was noticed after VUV photo-oxidation. These findings suggest that VUV irradiation provides a high potential for surface modification of fluorinated polymers which are known to be particularly resistant against functionalization by conventional surface modification techniques such as plasma treatment. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2215-2222, 1998
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
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  • 206
    Digitale Medien
    Digitale Medien
    Isomeric compositions in amide acids and poly(amic acid)s derived from 1-(trifluoromethyl)-2,3,5,6-benzenetetracarboxylic dianhydride (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1755-1765 
    Details
    ISSN: 0887-624X
    Schlagwort(e): 1-(trifluoromethyl)-2,3,5,6-benzenetetracarboxylic dianhydride ; amide acid ; poly(amic acid) ; isomeric unit ; nuclear magnetic resonance spectroscopy ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Two different poly(amic acid)s were synthesized by the polycondensations of 1-(trifluoromethyl)-2,3,5,6-benzenetetracarboxylic dianhydride (CF3DAN) with p-phenylene diamine and benzidine. In addition, an amide acid model compound was prepared from CF3DAN and aniline. Isomeric units in the poly(amic acid)s as well as the amide acid were investigated by 1H and 13C-nuclear magnetic resonance (NMR) spectroscopies. Spectroscopic results indicate that the major isomeric component was a CF3-meta-isomeric unit centered on the aromatic carbon substituted with the trifluoromethyl group. In particular, the amide acid compound was determined to be composed of 80 mol % CF3-meta-isomer and 20 mol % H-meta-isomer. Therefore, for the poly(amic acid)s, the minor isomeric component is speculated to be a H-meta-isomeric unit rather than a para-isomeric unit. The result might result mainly from the strong electron-withdrawable and bulky trifluoromethyl substituent in the CF3DAN monomer. The strong electron withdrawability might significantly enhance the reactivities of the adjacent carbons in the monomer to the nucleophilic attack of the amino nitrogen in the aniline and diamines, and consequently overcome the role of the bulkyness, ultimately leading to the amide acid and poly(amic acid)s rich with the CF3-meta-isomeric unit. In addition, a portion of the imide form was detected in the dried AN-CF3DAM-AN amide acid. Thus, the formation of imide linkage might be involved in a small portion for the dried poly(amic acid)s. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1755-1765, 1998
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
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  • 207
    Digitale Medien
    Digitale Medien
    Synthesis and characterization of new soluble aromatic polyimides from diaminotetraphenylimidazolinone and aromatic tetracarboxylic dianhydrides (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1767-1772 
    Details
    ISSN: 0887-624X
    Schlagwort(e): diaminotetraphenylimidazolinone ; soluble aromatic polyimides ; solubility ; thermal behavior ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A series of new soluble aromatic polyimides with inherent viscosities of 0.65-1.12 dL/g were synthesized from 1,3-bis(4-aminophenyl)-4,5-diphenylimidazolin-2-one and various aromatic tetracarboxylic dianhydrides by the conventional two-step procedure that included ring-opening polyaddition and subsequent thermal cyclodehydration. These polyimides could also be prepared by the one-pot procedure in homogeneous m-cresol solution. Most of the tetraphenyl-pendant polyimides were soluble in organic solvents such as N,N-dimethylacetamide, 1,3-dimethyl-2-imidazolidone, and m-cresol. Some polyimides gave transparent, flexible, and tough films with good tensile properties. The glass transition temperatures and 10% weight loss temperatures under nitrogen of the polyimides were in the range of 287-326 and 520-580°C, respectively. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1767-1772, 1998
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 208
    Digitale Medien
    Digitale Medien
    Preparation of poly(ε-caprolactone)-co-poly(acrylic acid) by radiation-induced grafting (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1805-1812 
    Details
    ISSN: 0887-624X
    Schlagwort(e): polycaprolactone ; irradiation ; graft copolymerization ; acrylic acid ; preirradiation grafting ; electron beam ; EB ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Acrylic acid was grafted onto poly(ε-caprolactone) (PCL) films by using electron beam (EB) preirradiation technique. The effect of reaction time, monomer concentration, radiation dose, time between irradiation and grafting, radiation atmosphere, and polymer crystallinity on the extent of grafting were studied. Silver and tin ions were attached to the grafted chains in order to study the grafting process. The irradiation in air was initially more rapid, but the final extent of grafting was the same when irradiated in nitrogen atmosphere. Maximum grafting extents exceeding 400% could be obtained. The optimal grafting was obtained at an acrylic acid to water ratio of 30 : 70. The grafting process could be initiated at a dose as low as 12 kGy. The grafting process proved to start at the surface and was extended into the bulk with time. The ability to form crystals was reduced as the grafting extent increased. The water uptake of the poly(ε-caprolactone)-graft-poly(acrylic acid) was increasing with increasing grafting extent, but reached a maximum of ca 100% for all grafting extents above 85%. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1805-1812, 1998
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
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  • 209
    Digitale Medien
    Digitale Medien
    Separation and enzymatic degradation of blend films of poly(L-lactic acid) and cellulose (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1861-1864 
    Details
    ISSN: 0887-624X
    Schlagwort(e): blend film ; poly (L-lactic acid) ; cellulose ; enzymatic degradation ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Blend films of poly(L-lactic acid) (PLLA) and cellulose with various composition was prepared by casting from trifluoroacetic acid solution. One hydroxyl group per each glucose unit was esterified by trifluoroacetic acid. The trifluoroacetyl group was hydrolyzed completely during the degradation. Weight losses for 90/10 and 75/25 PLLA/cellulose blends by proteinaze K were greatly increased compared with pure PLLA sample due to the large depression of the crystallinity of PLLA component, while cellulase was effective only for the degradation of pure cellulose film. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1861-1864, 1998
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 210
    Digitale Medien
    Digitale Medien
    Helical conformations of isotactic polyacetaldehyde and other isotactic polytrihaloacetaldehydes (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1855-1860 
    Details
    ISSN: 0887-624X
    Schlagwort(e): helical conformation ; stereospecific polymerization ; isotactic ; polyacetaldehyde ; polytrifluoroacetaldehyde (polyfluoral), polytrichloro-acetaldehyde (polychloral) ; polytribromoacetaldehyde (polybromal) ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Minimum potential energy helical conformations for a family of four isotactic polyacetaldehydes have been determined. Our results indicate that all of the polymers form irrational helices. Comparisons have been made with the reported structures for two of these stereoregular polymers based on earlier X-ray diffraction data. c-Axis values associated with the pitch of the helix for polyacetaldehyde and for polytrichloroacetaldehyde (polychloral) were experimentally measured to be 0.48 and 0.51 nm, respectively. Our calculated conformations afforded values for a helix pitch of 0.47 and 0.52 nm, respectively, which derive from a 3.9/1 helix for polyacetaldehyde and a 3.7/1 helix for polychloral. The structure for polytribromoacetaldehyde (polybromal) was predicted to be similar to that for polychloral. For polytrifluoroacetaldehyde (polyfluoral) and polyacetaldehyde, a number of helical conformations with similar energies were found. All of these conformations could be related to the polychloral helical structure. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1855-1860, 1998
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 211
    Digitale Medien
    Digitale Medien
    Polycyclic phosphonate resins: Thermally cross-linkable intermediates for flame-retardant materials (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1911-1918 
    Details
    ISSN: 0887-624X
    Schlagwort(e): polycyclic methylphosphonates ; polycyclic phenylphosphonates ; phenol-formaldehyde resins ; ring-opening polymerization ; flame retardance ; matrix-assisted laser desorption ionization-time of flight mass spectrometry ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Two series of polycyclic phosphonates were synthesized by reacting p-substituted phenol-formaldehyde resins with excess phosphonic dichlorides under dilute conditions in a polar aprotic solvent. MALDI-TOF was used to detect the absolute masses of different species formed under these conditions. The presence of phosphorus-containing species was also confirmed by 31P-NMR. The polycyclics were subjected to ring-opening polymerization simultaneously with a transesterification reaction with commercial polycarbonates in order to cross-link the polymers and to impart flame retardancy to the final thermosetting materials. Thermal properties of the polycarbonates containing phosphonate moieties were determined by thermogravimetric analysis and differential scanning calorimetry techniques. Percent char yields of the final thermosetting materials were considerably higher than that of the linear polycarbonates. Polycyclic phosphonates, therefore, can potentially be used to impart flame retardance to polymers. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1911-1918, 1998
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
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  • 212
    Digitale Medien
    Digitale Medien
    Unusually facil cis to trans isomerization of a polypropiolate bearing a long alkyl chain polymerized using a [Rh(norbornadiene)Cl]2 catalyst: An ESR study (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2457-2461 
    Details
    ISSN: 0887-624X
    Schlagwort(e): polyalkylpropiolate ; Rh complex catalyst ; isomerization ; ESR ; soliton ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Alkylpropiolate having n-hexadecyl moiety in the ester group was stereospecifically polymerized with a [Rh(norbornadiene)Cl]2 complex catalyst in alcohol to give rise to cis-transoid polyacetylenes in high yields. The unusually facile cis to trans isomerization for the polymer was found to be induced when the polymer was warmed to even less than ca. 57°C. Under these conditions ESR spectra bearing hyperfine structures due to the radicals generated by the rotational scission in the cis-π bond were observed. This isomerization induced a large g value shift in the ESR spectra together with an increase of the radical concentration during the isomerization, indicating formation of planar conjugated trans sequences that stabilize mobile unpaired electrons as solitons. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2457-2461, 1998
    Zusätzliches Material: 4 Ill.
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  • 213
    Digitale Medien
    Digitale Medien
    Poly[(S)-(+)-2-methylbutyl]pentylsiloxane (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 169-177 
    Details
    ISSN: 0887-624X
    Schlagwort(e): polysiloxane ; hexagonal columnar mesophase ; optically active polymers ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Poly[(S)-(+)-2-methylbutyl]pentylsiloxane has been synthesized by anionic ring opening polymerization of the corresponding strained cyclic trisiloxane \documentclass{article}\pagestyle{empty}\begin{document}$ (D^{\rm{MeBu, Pe}}_{3}) $\end{document} with cryptated lithium (Li+/[211]) as counterion. The polymer did not show the low and high temperature crystalline phases, that are generally found for poly(di-n-alkylsiloxane)s. Instead, the material formed a hexagonal columnar mesophase until it melted around 400°C. MAS and solution 13C- and 29Si-NMR, polarizing microscopy and WAXS indicated an unexpectedly regular chain structure. It was tentatively concluded that the steric interaction of the (S)-(+)-2-methylbutyl side chains introduces sufficient regularity of the tacticity and that the chains tend to adopt a defect helix conformation. On the other hand, DSC showed the presence of a glass transition at -113°C, indicating a high flexibility of the backbone. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 169-177, 1998
    Zusätzliches Material: 7 Ill.
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  • 214
    Digitale Medien
    Digitale Medien
    Efficiency of mercaptan chain transfer agents in emulsion copolymerizations. I. Influence on kinetics and microstructure. Modeling of radical desorption (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 157-168 
    Details
    ISSN: 0887-624X
    Schlagwort(e): emulsion polymerization ; reaction calorimetry ; chain transfer agents ; kinetics ; radical desorption ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The effect of chain transfer agents (CTA) on the emulsion copolymerization of styrene and butyl acrylate was studied in a bench scale 7 L reactor. On-line estimates of conversion were obtained through the joint use of calorimetric measurements and fast gravimetric data. Off-line measurements of partial conversions, molecular weight distribution (MWD), glass transition temperature (Tg), and particle diameter were also performed in order to investigate the effect of two mercaptans (tert-butanethiol and n-dodecanethiol) on both the kinetics of the polymerization process and the microstructure-dependent properties of the copolymer. The obtained experimental results were interpreted in terms of radical desorption and diffusive limitations of the CTA between the oil droplets and the particles. A model has been derived to compute the kinetic constants, the number of radicals per particle, and both the GPC/SEC diagrams and DSC thermograms related to MWD and Tg measurements, respectively. Several batch and semibatch examples are proposed to show that these important variables are satisfactorily fit by the model. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 157-168, 1998
    Zusätzliches Material: 7 Ill.
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  • 215
    Digitale Medien
    Digitale Medien
    Graft formation and chain scission in blends of polyamide-6 and -6.6 with maleic anhydride containing polymers (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 179-188 
    Details
    ISSN: 0887-624X
    Schlagwort(e): PA ; polyamide ; maleic anhydride ; graft formation ; crosslinking ; rheology ; morphology ; crystallinity ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The in situ formation of a compatibilizer, consisting of a copolymer of PA grafted onto a maleic anhydride (MA) containing polymer, is essential for the morphology and properties of the corresponding PA blends. In this study four blends, containing PA-6 or PA-6.6 and EPDM-g-MA or poly(styrene-co-maleic anhydride) (SMA; 28 wt % MA), were prepared and characterized. Chemical analyses showed that the amount of PA graft is independent of the blend composition. Going from EPDM-g-MA to SMA the MA content of the original MA-containing polymer increases, which in the corresponding blends results in an increase in the number of PA grafts and a decrease in the length of the PA grafts. In the SMA blends the number averaged molecular weight of the grafted PA is only about 200 g/mol. It is postulated that the water molecule, released upon imide formation at the PA/(MA-containing polymer) interface, hydrolyses a PA amide group, resulting in a new amine end group, which in its turn reacts with the MA-containing polymer, etc. Differential scanning calorimetry shows that the degree of crystallinity of the PA phase is decreased only when the size of the PA phase between the MA-containing polymer domains approaches the PA crystalline lamellar thickness. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 179-188, 1998
    Zusätzliches Material: 5 Ill.
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  • 216
    Digitale Medien
    Digitale Medien
    Correlation of chemical structure and swelling behavior in N-alkylacrylamide hydrogels (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2095-2102 
    Details
    ISSN: 0887-624X
    Schlagwort(e): N-alkylacrylamide ; N-isopropylacrylamide ; hydrogel ; thermosensitive ; volume transition ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The thermoshrinking properties have been studied for the series of N-alkyl-acrylamide hydrogels (alkyl = methyl, ethyl, isopropyl, and n-propyl), which were prepared by free-radical copolymerization of the alkylacrylamide, sodium acrylate, and N,N′-methylenebis(acrylamide) (BIS) in aqueous solution. The reaction mixtures were prepared using the same nominal compositions in an effort to study the effect of the chemical structure of the alkyl substituent on the gel swelling behavior as a function of temperature. The alkyl group was found to have a pronounced effect on the features of gel swelling. Generally, larger alkyl chains produced dramatic decreases in gel transition temperature. In addition, a change in the nature of the swelling behavior from continuous to discontinuous was noted upon changing the alkyl group from ethyl to the two propyl derivatives. Discontinuous transitions were accompanied by hysteresis. The transition temperatures of the isomeric propyl derivatives were found to differ by 12°C, with n-propyl exhibiting the lower value. Additionally, a quantitative correlation was found between the gel transition temperatures and the water/octanol partition coefficients for appropriately chosen small molecule model compounds. The transition temperatures of other gels in the series, including the cyclopropyl derivative and the n-propyl/isopropyl copolymer gels (NIPA/NNPA), also fit this correlation. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2095-2102, 1998
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  • 217
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    Digitale Medien
    Morphology control of organometallic domains in phase-separated poly(styrene-block-ferrocenyldimethylsilanes) (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2147-2150 
    Details
    ISSN: 0887-624X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: No abstract.
    Zusätzliches Material: 4 Ill.
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  • 218
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    Palladium-catalyzed modification of poly(p-bromostyrene) with 4-(phenylamino)azobenzene. Optical properties of new azobenzene group-containing polystyrene (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2155-2160 
    Details
    ISSN: 0887-624X
    Schlagwort(e): palladium complex ; polymer reaction ; azobenzene ; cis-trans isomerization ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: No abstract.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 219
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    Digitale Medien
    Syntheses and biological activities of α-methoxy-exo-3,6-epoxy-1,2,3,6-tetrahydrophthaloyl-5-fluorouracil and its polymers (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2177-2184 
    Details
    ISSN: 0887-624X
    Schlagwort(e): α-methoxy-exo-3,6-epoxy-1,2,3,6-tetrahydrophthaloyl-5-fluorouracil (METFU) ; poly(METFU-co-AA) ; poly(METFU-co-VAc) ; photopolymerization ; molecular weight ; in vitro cytotoxicity ; in vivo antitumor activity ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The new monomer, α-methoxy-exo-3,6-epoxy-1,2,3,6-tetrahydrophthaloyl-5-fluorouracil (METFU), was synthesized by the reaction of 5-fluorouracil (5-FU) and exo-3,6-epoxy-1,2,3,6-tetrahydrophthalic anhydride (ETA) in order to prepare polymers containing 5-FU moiety. Poly(α-methoxy-exo-3,6-epoxy-1,2,3,6-tetrahydrophthaloyl-5-fluorouracil) [poly(METFU)], poly(α-methoxy-exo-3,6-epoxy-1,2,3,6-tetrahydrophthaloyl-5-fluorouraci-co-acrylic acid) [poly(METFU-co-AA)], and poly(α-methoxy-exo-3,6-epoxy-1,2,3,6-tetrahydrophthaloyl-5-fluorouracil-co-vinyl acetate) [poly(METFU-co- VAc)] were synthesized by photopolymerizations using 2,2-dimethoxy-2-phenylacetophenone (DMP) as an initiator. The synthesized METFU and the polymers were identified by FTIR and 1H-NMR spectroscopies. The contents of METFU in poly(METFU-co-AA) and poly(METFU-co-VAc) determined by elemental analysis were 52 and 60 mol %, respectively. The average molecular weights and polydispersity indices determined with GPC were as follows: Mn = 9,400, Mw = 11,400 Mw/Mn = 1.21 for poly(METFU), Mn = 14,400, Mw = 26,800, Mw/Mn = 1.86 for poly(METFU-co-AA), and Mn = 23,100, Mw = 33,000, Mw/Mn = 1.43 for poly(METFU-co-VAc). The in vitro cytotoxicities of samples were evaluated with mouse mammary carcinoma (FM3A), mouse leukemia (P388), and human histiocytic lymphoma (U937) as cancer cell lines, and mouse liver cells (AC2F) as a normal cell line. The in vivo antitumor activities of synthesized polymers against mice bearing the sarcoma 180 tumor cell line were greater than those of 5-FU at concentrations of 0.8 and 80 mg/kg. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2177-2184, 1998
    Zusätzliches Material: 3 Ill.
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  • 220
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    Transformation of the cationic growing center of poly(tetrahydrofuran) into an anionic one by bis(pentamethylcyclopentadienyl)samarium (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2209-2214 
    Details
    ISSN: 0887-624X
    Schlagwort(e): cationic polymerization ; anionic polymerization ; transformation ; samarium ; block copolymerization ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Transformation of the cationic growing center of living poly(tetrahydrofuran) [poly(THF)] into an anionic one was achieved in high efficiency (62%) by the end-capping of living poly(THF) with potassium iodide followed by the reduction with bis(pentamethylcyclopentadienyl)samarium (Cp*2Sm), whereas the direct reduction with Cp*2Sm without the end-capping resulted in the formation of poly(THF) with pentamethylcyclopentadienyl group at the terminal. The increase in the molecular weight of poly(THF) after the reduction was observed, which indicates the presence of the dimerization of poly(THF) during the reduction. The polymerization of a variety of electrophilic monomers including δ-valerolactone, 2-oxo-1,3-dioxane, and alkyl methacrylates with the macroanion provided good yields of the corresponding block copolymers consisting of both cationically and anionically polymerizable monomers. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2209-2214, 1998
    Zusätzliches Material: 4 Ill.
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  • 221
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    Digitale Medien
    Synthesis and properties of new Si—H-containing polymers (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2275-2282 
    Details
    ISSN: 0887-624X
    Schlagwort(e): condensation polymerization ; preceramic ; dehydrocoupling ; hydrosilylation ; gelation ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Poly[(methylsilylene)ethynylene] (1) and poly[2,5-thiophenediyl(methylsilylene)] (2) are prepared in good yields. Thermogravimetric analysis and differential scanning calorimetry indicate the Si—H group to increase the pyrolysis residue yields. Gelation was achieved from polymer 1 to get improved preceramic materials. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2275-2282, 1998
    Zusätzliches Material: 3 Ill.
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  • 222
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    Digitale Medien
    Mechanisms of thermal degradation of polystyrene, polymethacrylonitrile, and their copolymers on flash pyrolysis (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2315-2330 
    Details
    ISSN: 0887-624X
    Schlagwort(e): thermal degradation mechanism ; poly(styrene-co-methacrylonitrile) ; pyrolysis gas chromatography ; back-biting reaction ; depolymerization ; boundary effect ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The mechanism of thermal degradation of homopolymers of styrene (St) and methacrylonitrile (MAN) and their copolymers was investigated theoretically and experimentally by the pyrolysis gas chromatography using a Curie-point pyrolyzer. Poly(St-co-MAN)s generate dimers and trimers as well as monomers by flash pyrolysis. Parameter α was proposed to account for the competition between the back-biting reaction and depolymerization. The back-biting parameter α is defined as the ratio of rate constants, α = kbb/kdp, where kbb is the rate constant for the back-biting reaction and kdp is that for depolymerization. The back-biting process is followed by β-scission, where dimer and trimer are generated, and directly correlated with the C - H bond dissociation energies in the polymer chain. Using the back-biting parameter α, where 1/α is equal to the zip length n in depolymerization, the boundary effect for the difference of monomer yields from the homopolymers of St and MAN and their copolymers is well explained. The calculated values of boundary effect parameters, βSt and βMAN, agreed well with the experimental results. It was found that thermal degradation mechanisms of homo- and copolymers of vinyl compounds can be analyzed comprehensively using the back-biting parameter α and the boundary effect parameter β. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2315-2330, 1998
    Zusätzliches Material: 10 Ill.
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  • 223
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    Digitale Medien
    New polymer syntheses XCIII. Hyperbranched homo- and copolyesters derived from gallic acid and β-(4-hydroxyphenyl)-propionic acid (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2347-2357 
    Details
    ISSN: 0887-624X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The hyperbranched homopolyester of gallic acid (GA) was prepared by polycondensation of acetylated gallic acid in bulk. Copolyesters of gallic acid and 3-hydroxybenzoic acid (3-HBA) or β-(4-hydroxyphenyl)propionic acid (HPPA) were prepared via the silylated monomers. The degree of branching was varied in both series via the molar fraction of gallic acid. A model reaction with silylated 4-methoxybenzoic acid suggests that all three acetoxy groups of gallic acid can react by ester interchange reactions under the chosen reaction conditions. Furthermore, highly branched copolyesters derived from equimolar ratios of HPPA and 2-, 3-, or 4-hydroxybenzoic acid, vanillic acid, or 4-hydroxycinnamic acid were synthesized. All these copolyesters were found to be amorphous with glass transition temperatures (Tg's) far below that of the hyperbranched poly(gallic acid). © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2347-2357, 1998
    Zusätzliches Material: 8 Ill.
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  • 224
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    Digitale Medien
    Emulsion polymerization of styrene using an alkali-soluble random copolymer as polymeric emulsifier (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2865-2872 
    Details
    ISSN: 0887-624X
    Schlagwort(e): alkali-soluble random copolymer ; polymeric emulsifier ; aggregate ; hairy ASR layer ; rate of polymerization ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: An alkali-soluble random copolymer (ASR), poly(styrene/α-methylstyrene/acrylic acid), was used as a polymeric emulsifier in the emulsion polymerization of styrene. The calorimetric technique was applied to study the kinetics of emulsion polymerization of styrene using ASR and a conventional ionic emulsifier, sodium dodecyl benzenesulfonate (SDBS). ASR could form aggregates like micelles, and the solubilization ability of the aggregates was dependent on the neutralization degree of ASR. The rate of polymerization in the ASR system was lower than that in the SDBS system. This result can be explained by the creation of a hairy ASR layer around the particle surface, which decreases the diffusion rate of free radicals through this region. Although a decrease in particle size was observed, the rate of polymerization decreased with increasing ASR concentration. The higher the concentration of ASR is, the thicker and denser ASR layer may be, and the more difficult it would therefore be for radicals to reach the particle through this layer of ASR. The rate of polymerization decreased with increasing the neutralization degree of ASR. The aggregates with high neutralization of ASR are less efficient in solubilizing the monomer and capturing initiator radicals than that of the lower neutralization degree, which leads to decrease in rate of polymerization. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2865-2872, 1998
    Zusätzliches Material: 8 Ill.
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  • 225
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    Digitale Medien
    Cationic polymerization of 1,3-dioxepane in the presence of 2,2-bis(hydroxymethyl)butanol (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2899-2903 
    Details
    ISSN: 0887-624X
    Schlagwort(e): cationic ring-opening polymerization ; poly(1,3-dioxepane) triol ; 2,2-bis(hydroxymethyl)butanol ; transacetalization ; activated monomer mechanism ; activated chain mechanism ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Cationic polymerization of 1,3-dioxepane (DOP) initiated by triflic acid was carried out in the presence of 2,2-bis(hydroxymethyl)butanol (BHMB). The structure and molecular weight of the products were characterized by GPC and NMR spectra. The results showed that molecular weight of the polyacetal obtained could be controlled by the initial mole ratio of DOP/BHMB. GPC showed that as the mole ratio of BHMB/DOP increased, the content of cyclic oligomers also increased. Proton, 13C and 2D HMQC-fg NMR demonstrated that no hydroxymethyl group of BHMB appeared as an end group. It was also illustrated by proton NMR that some BHMB units existed in cyclic oligomers. The mechanism of formation of cyclic oligomers was discussed. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2899-2903, 1998
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  • 226
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    Atom transfer radical polymerization of styrene initiated by polychloroalkanes and catalyzed by CuCl/2,2′-bipyridine: A kinetic and mechanistic study (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2933-2947 
    Details
    ISSN: 0887-624X
    Schlagwort(e): atom transfer radical polymerization ; styrene ; initiation ; polychloroalkanes ; redox telomerization ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A series of polychloroalkanes, known as telogen agents for redox telomerization, were used as initiators for atom transfer radical polymerization (ATRP) of styrene using the heterogeneous CuCl/2,2′-bipyridine catalyst. In copper-catalyzed redox telomerization, the reactivity of RCCl3-type telogens is strongly influenced by the nature of the R group. In ATRP, the 2,2′-bipyridine ligand levels the activity of the catalytic system in such a way that all 1,1,1-trichloroalkanes are efficient initiators in ATRP, whatever the R group. The nature of this substituent influences the overall rate of polymerization through both the number of active sites per chain and the [Cu (I)]/[Cu (II)] ratio. By the combining of several analytical techniques, it is proved that some polychloroalkanes such as CCl3CO2CH3, CCl3CF3, or CCl4 are bifunctional initiators. Finally, a general mechanism of initiation is proposed. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2933-2947, 1998
    Zusätzliches Material: 6 Ill.
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  • 227
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    Polymerization of diphenylacetylenes having very bulky silyl groups and polymer properties (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2721-2725 
    Details
    ISSN: 0887-624X
    Schlagwort(e): poly(diphenylacetylene) ; tantalum catalyst ; metathesis polymerization ; thermal stability ; gas permeability ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Polymerization and polymer properties of 1-phenyl-2-[4-(triphenylsilyl)phenyl]acetylene (pPh3SiDPA) and 1-phenyl-2-[4-(triisopropylsilyl)phenyl]acetylene (piPr3SiDPA), which have very bulky silyl groups, were examined. These monomers polymerized in good yields in the presence of TaCl5-based catalysts. The highest weight-average molecular weights of poly(pPh3SiDPA) and poly(piPr3SiDPA) reached about 1 × 106 and 4.8 × 106, respectively. The polymers were yellow to orange-colored solids which were soluble in toluene, chloroform, etc., and provided free-standing films by solution casting. The onset temperatures of weight loss of poly(pPh3SiDPA) and poly(piPr3SiDPA) in TGA in air were 430 and 270°C, respectively. The oxygen permeability coefficients of poly(pPh3SiDPA) and poly(piPr3SiDPA) at 25°C were 3.8 and 20 barrers, respectively, and relatively small. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2721-2725, 1998
    Zusätzliches Material: 4 Ill.
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  • 228
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    Free radical dispersion polymerization of styrene in a mixture of 2-propanol and tetrahydrofuran (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2757-2761 
    Details
    ISSN: 0887-624X
    Schlagwort(e): free radical polymerization ; high-conversion model ; solvent effect ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Free radical dispersion polymerization of styrene in a mixture of 2-propanol and tetrahydrofuran was carried out at 70°C up to high conversions. The influence of the change of the critical chain length on the evolution of the insoluble polymer component was examined. Monomer conversion and the formation of the insoluble polymer component were measured in order to test a mathematical model presented in our previous article. The critical polymer chain length i0, the initiation rate constant kd, and the ratio kp/kt1/2, where kp and kt are propagation and termination rate constants, respectively, have been obtained and compared with those reported in the literature. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2757-2761, 1998
    Zusätzliches Material: 6 Ill.
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  • 229
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    Synthesis and electrical-magnetic properties of polyaniline composites (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2799-2805 
    Details
    ISSN: 0887-624X
    Schlagwort(e): polyaniline (PANI) ; electrical-magnetic properties ; emeraldine base (EB) ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Composites of polyaniline (PANI) with both conducting and ferromagnetic feature were synthesized by an improved method proposed by the authors. The electrical and ferromagnetic properties of the composites were measured as a function of the concentration of KOH solution used during polymerization. The conductivity of the composites at room temperature decreases with the increase of the concentration of KOH; the maximum conductivity of 8.0 × 10-1 S/cm can be obtained when 25 wt % of concentration of KOH was used. For a high concentration of KOH, ferromagnetic properties of the composites including a high saturated magnetization (∼ 10.0 emu/g) depending on the concentration of KOH solution and a lower coercive force (Hc ≈ 0) independent of the concentration of KOH solution were observed. It has been demonstrated that magnetic particles (Fe3O4) with nanometer size in the composites can be attributed to the ferromagnetic properties of the composites observed. For a lower concentration of KOH solution, on the other hand, the magnetic properties of the composites can be decomposed to Curie susceptibility χc depending on the temperature and Pauli susceptibility χP independent of the temperature. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2799-2805, 1998
    Zusätzliches Material: 7 Ill.
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  • 230
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    New hydrocarbon side chain liquid crystalline polysiloxane polymers: Synthesis, characterization, and thermotropic behavior (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2849-2863 
    Details
    ISSN: 0887-624X
    Schlagwort(e): liquid crystals ; all hydrocarbon ; side chain ; polysiloxane polymers ; smectic B phase ; smectic E phase ; X-ray diffraction ; spin-lattice relaxation time ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A series of new and high-purity hydrocarbon liquid crystal monomers were synthesized through the acylation reaction, deoxygenation reaction, and Grignard reaction. 1H-NMR spectra and elemental analyses were used to examine their purity. The liquid crystalline polysiloxane polymers were obtained by grafting the monomers onto poly(methylhydrosiloxane). The thermal transition temperature, mesomorphic properties, and mesophase textures of the monomers and the polymers were determined by differential scanning calorimetry (dsc), polarized optical microscopy, and X-ray diffraction analysis. Moreover, we observed the even-odd effect of the smectic/isotropic transition temperature with the length variation of the substituents. In this study, we found by X-ray diffraction that the liquid crystalline polysiloxane polymers undergo a transition from smectic B to smectic E mesophase. However, dsc has difficulty detecting the phase transition process. By considering the spin-lattice relaxation time (T1), we can systematically explain the relation between the flexibility of the substituent with the smectic/isotropic transition temperature. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2849-2863, 1998
    Zusätzliches Material: 9 Ill.
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  • 231
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    Determination of chain transfer constant to dodecanethiol in styrene/methyl methacrylate and butyl acrylate/methyl methacrylate copolymerization and effect of chain length on composition and stereochemical configuration of copolymers (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2913-2925 
    Details
    ISSN: 0887-624X
    Schlagwort(e): dodecanethiol ; styrene-methyl methacrylate ; butyl acrylate-methyl methacrylate ; chain transfer constants ; stereochemical configuration ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Free radical copolymerization of styrene/methyl methacrylate (S/MMA) and butyl acrylate/methyl methacrylate (BA/MMA) in the presence of n-dodecanthiol (DDT) has been studied at 60°C in a 3 mol/L benzene solution using 2,2′-azobis(isobutyronitrile) (AIBN) as initiator. Overall chain transfer constant to DDT has been determined for both copolymerization systems, as a function of monomer feed composition using complete molecular weight distribution and the Mayo method. Overall transfer coefficients have values which are dependent on both monomer feed composition and individual comonomer transfer values. Composition, sequence distribution, and stereoregularity of copolymers obtained are, in our experimental conditions, independent of copolymer molecular weight. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2913-2925, 1998
    Zusätzliches Material: 7 Ill.
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  • 232
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    Spontaneous alternating copolymerization of N-phenylmaleimide with ethyl α-phenylacrylate (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2927-2931 
    Details
    ISSN: 0887-624X
    Schlagwort(e): N-phenylmaleimide ; ethyl α-phenylacrylate ; alternating copolymer ; contact-charge transfer complex ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The spontaneous copolymerization of N-phenylmaleimide (NPMI) (M1) with ethyl α-phenylacrylate (EPA)(M2) were carried out in dioxane at 85°C. A high alternating tendency was observed. The monomer reactivity ratios were r1 = 0.07 ±0.01 and r2 = 0.09 ± 0.02. The maximum copolymerization rate and molecular weight occurs at 70-80 mol% (M1) in feed ratio. The spontaneous alternating copolymerization is considered to be carried out via a contact-type charge transfer complex (CTC) formed between the monomers. Thermogravimetric analyses (TGA) indicate the resulting copolymers have high thermal stability. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2927-2931, 1998
    Zusätzliches Material: 2 Ill.
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  • 233
    Digitale Medien
    Digitale Medien
    Synthesis and characterization of biodegradable poly(L-aspartic acid-co-PEG) (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2949-2959 
    Details
    ISSN: 0887-624X
    Schlagwort(e): aspartic acid anhydride ; poly(ethylene glycol) ; poly(L-aspartic acid-co-PEG) ; biodegradable polymers ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The melt polycondensation reaction of the prepolymer prepared from N-(benzyloxycarbonyl)-L-aspartic acid anhydride (N-CBz-L-aspartic acid anhydride) and low molecular weight poly(ethylene glycol) (PEG) using titanium isopropoxide (TIP) as a catalyst produced the new biodegradable poly(L-aspartic acid-co-PEG). This new copolymer had pendant amine functional groups along the polymer backbone chain. The optimal reaction conditions for the preparation of the prepolymer were obtained by using a 0.12 mol % of p-toluenesulfonic acid with PEG 200 for 48 h. The weight-average molecular weight of the prepolymer increased from 1,290 to 31,700 upon melt polycondensation for 6 h at 130°C under vacuum using 0.5 wt % TIP as a catalyst. The synthesized monomer, prepolymer, and copolymer were characterized by FTIR, 1H- and 13C-NMR, and UV spectrophotometers. Thermal properties of the prepolymer and the protected copolymer were measured by DSC. The glass transition temperature (Tg) of the prepolymer shifted to a significantly higher temperature with increasing molecular weight via melt polycondensation reaction, and no melting temperature was observed. The in vitro hydrolytic degradation of these poly(L-aspartic acid-co-PEG) was measured in terms of molecular weight loss at different times and pHs at 37°C. This pH-dependent molecular weight loss was due to a simple hydrolysis of the backbone ester linkages and was characterized by more rapid rates of hydrolysis at an alkaline pH. These new biodegradable poly(L-aspartic acid-co-PEG)s may have potential applications in the biomedical field. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2949-2959, 1998
    Zusätzliches Material: 10 Ill.
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  • 234
    Digitale Medien
    Digitale Medien
    Syntheses and antitumor activities of medium molecular weight polymers containing 5-fluorouracil (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2985-2992 
    Details
    ISSN: 0887-624X
    Schlagwort(e): α-ethoxy-3,6-endo-methylene-1,2,3,6-tetrahydrophthaloyl-5-fluorouracil (EMTFU) ; 5-fluorouracil (5-FU) ; poly(EMTFU) ; poly(EMTFU-co-AA) ; poly(EMTFU-co-VAc) ; average molecular weights ; in vitro cytotoxicities ; in vivo antitumor activity ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The new monomer α-ethoxy-3,6-endo-methylene-1,2,3,6-tetrahydrophthaloyl-5-fluorouracil (EMTFU) was synthesized from 5-fluorouracil (5-FU) and α-ethoxy-3,6-endo-methylene-1,2,3,6-tetrahydrophthaloyl chloride (EMTC). Poly(α-ethoxy-3,6-endomethylene-1,2,3,6-tetrahydrophthaloyl-5-fluorouracil) [poly(EMTFU)], poly(α-ethoxy-3,6-endo-methylene-1,2,3,6-tetrahydrophthaloyl-5-fluorouracil-co-acrylic acid) [poly(EMTFU-co-AA)], and poly(α-ethoxy-3,6-endomethylene-1,2,3,6-tetrahydrophthaloyl-5-fluorouracil-co-vinyl acetate) [poly(EMTFU-co-VAc)] were synthesized by photopolymerizations using 2,2-dimethoxy-2-phenylacetophenone (DMP) as the photoinitiator. The synthesized EMTFU and its polymers were identified by Fourier transfer infrared (FT-IR), 1H nuclear magnetic resonance (NMR), and 13C-NMR spectroscopies. The contents of EMTFU in poly(EMTFU-co-AA) and poly(EMTFU-co-VAc) determined by elemental analysis were 46 and 70 mol %, respectively. The number average molecular weights of the synthesized polymers determined by gel permeation chromatography (GPC) were in range of 17,200-20,900. The in vitro cytotoxicities of samples were evaluated with mouse mammary carcinoma (FM3A), mouse leukemia (P388), and human histiocytic lymphoma (U937) as cancer cell lines and AC2F as a normal cell line. The cytotoxicities of 5-FU and synthesized samples against cancer cell lines increased in following orders: 5-FU ≈ EMTFU 〉 poly(EMTFU-co-AA) 〉 poly(EMTFU) 〉 poly(EMTFU-co-VAc). The in vivo antitumor activities of the synthesized samples against mice bearing the sarcoma 180 tumor cell line were evaluated. The in vivo antitumor activities of EMTFU and its polymers were greater than those of 5-FU at a dosage of 80 mg/kg. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2985-2992, 1998
    Zusätzliches Material: 2 Ill.
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  • 235
    Digitale Medien
    Digitale Medien
    Polymerizations of olefins and diolefins catalyzed by monocyclopentadienyltitanium complexes containing a (dimethylamino)ethyl substituent and comparison with ansa-zirconocene systems (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 319-328 
    Details
    ISSN: 0887-624X
    Schlagwort(e): metallocenes ; Ziegler-Natta catalysis ; olefin polymerizations ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: {[2-(dimethylamino)ethyl]cyclopentadienyl}titanium trichloride (CpNTiCl3, 1) was activated with methylaluminoxane (MAO) to catalyze polymerizations of ethylene (E), propylene (P), ethylidene norbornene (ENB), vinylcyclohexene (VCH), and 1,4-hexadiene (HD). The dependence of homopolymerization activity (A) of 1/MAO on olefin concentration ([M]n) is n = 2.0 ± 0.5 for E and n = 1.8 ± 0.2 for P. The value of n is 2.4 ± 0.2 for CpTiCl3/MAO catalysis of ethylene polymerization; this system does not polymerize propylene. 1/MAO catalyzes HD polymerization at one-tenth of AH for 1-hexene, probably because of chelation effects in the HD case. The copolymerization of E and P has reactivity ratios of rE = 6.4 and rP = 0.29 at 20°C, and rErP = 1.9, which suggests 1/MAO may be a multisite catalyst. The copolymerization activity of CpTiCl3/MAO is 50 times smaller than that of CpNTiCl3/MAO. Terpolymerization of E/P/ENB has A of 105 g of polymer/(mol of Ti h), incorporates up to 14 mol % (∼ 40 wt %) of ENB, and high MW's of 1 to 3 × 105. All of these parameters are surprisingly insensitive to the ENB concentration. The E/P/VCH terpolymerization has comparable A value of (1.3 ± 0.3) × 105 g/(mol of Ti h). The incorporation of VCH in terpolymer increases with increasing [VCH]. Terpolymerization with HD occurs at about one-third of the A of either ENB or VCH; the product HD-EPDM is low in molecular weight and contains less than 4% of HD. These terpolymerization results are compared with those obtained previously for three zirconocene precursors: rac-ethylenebis(1-η5-indenyl)dichlorozirconium (6), rac-(dimethylsilylene)bis(1-η5-indenyl)dichlorozirconium (7), and ethylenebis(9-η5-fluorenyl)dichlorozirconium (8). The last compound is a particularly poor terpolymerization catalyst; it incorporates very little VCH or HD and no ENB at all. 7/MAO is a better catalyst for E/P/VCH terpolymerization, while 6/MAO is superior in E/P/HD terpolymerization. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 319-328, 1998
    Zusätzliches Material: 3 Ill.
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  • 236
    Digitale Medien
    Digitale Medien
    Synthesis and properties of widely conjugated polyacetylenes having anthryl and phenanthryl pendant groups (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 3131-3137 
    Details
    ISSN: 0887-624X
    Schlagwort(e): metathesis polymerization ; poly(arylacetylene) ; conjugated polymer ; tungsten catalyst ; absorption spectrum ; fluorescence spectrum ; thermal stability ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The metathesis polymerization of 1- and 2-ethynylanthracenes (1-EA and 2-EA) and 2- and 3-ethynylphenanthrenes (2-EP and 3-EP) in the presence of various WCl6-based catalysts produced widely conjugated soluble polymers with relatively high molecular weights. The highest weight-average molecular weights of poly(1-EA) and poly(2-EA) reached 61,000 and 26,000, respectively, when Ph4Sn was used as cocatalyst, while those of poly(2-EP) and poly(3-EP) reached 23,000 and 65,000, respectively, with Ph3Bi as cocatalyst. In contrast, MoCl5-based catalysts were hardly or not effective for these monomers. A large red-shifted peak was observed centering at 570 nm (the cutoff at 750 nm) in the absorption spectrum of poly(1-EA), while the red-shifted peaks were seen around 500 nm (the cutoffs near 700 nm) in the spectra of other polymers, indicating wide conjugations of the polymer chains. The configurational structures of all the polymers confirmed by DSC and 1H-NMR were trans structures. However, poly(1-EA) and poly(3-EP) appeared to consist partly of cis structures in their main chains. All of the present polymers showed relatively high thermal stability in air compared with poly(phenylacetylene). © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 3131-3137, 1998
    Zusätzliches Material: 4 Ill.
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  • 237
    Digitale Medien
    Digitale Medien
    Control of molecular weight of the polymers produced during the crystalline-state photopolymerization of diethyl cis,cis-muconate as studied by gel permeation chromatography and scanning electron micrography (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 3147-3155 
    Details
    ISSN: 0887-624X
    Schlagwort(e): topochemical polymerization ; radical polymerization ; molecular weight control ; solid-state photoreaction ; diethyl muconate ; microcrystals ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The molecular weight and its distribution of the resulting polymers were investigated during the crystalline-state photopolymerization of diethyl cis,cis-muconate (EMU). EMU crystals were prepared by several methods, recrystallization, milling, freeze drying, and precipitation, to obtain the crystals with various sizes of 10-6 to 10-2 m. After crystalline-state photopolymerization via a crystal-to-crystal process, polymer crystals were isolated and characterized by optical microphotography and scanning electron micrography. Molecular weight and its distribution were determined by gel permeation chromatography with 1,1,1,3,3,3-hexafluoro-2-propanol and by intrinsic viscosity in trifluoroacetic acid. It was revealed that the size of the EMU crystals depended on the method used for the crystal preparation, and that the molecular weight of the polymer decreased as the crystal size became small. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 3147-3155, 1998
    Zusätzliches Material: 3 Ill.
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  • 238
    Digitale Medien
    Digitale Medien
    The thermal decomposition of diazoresin-SDS in aqueous solution or in solid film (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 3193-3195 
    Details
    ISSN: 0887-624X
    Schlagwort(e): diazoresin ; sodium dodecyl sulfate ; hydrophobic interaction ; thermostability ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: No abstract.
    Zusätzliches Material: 3 Ill.
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  • 239
    Digitale Medien
    Digitale Medien
    Oligomerization and cyclization of 1,2-ethanedithiol (EDT), HSCH2CH2SH, by selenium dioxide and iodine (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 379-390 
    Details
    ISSN: 0887-624X
    Schlagwort(e): selenium containing polymers ; poly(disulfide) polymers ; 1,2-ethanedithiol oxidation ; nuclear magnetic resonance ; Raman spectroscopy ; selenotrisulfide/disulfide chain and ring polymers ; mechanism of formation of selenotrisulfide polymers ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The reaction of 1,2 ethanedithiol (EDT) with selenous acid in water or alcohol leads to selenopolysulfide chains or cycles, (C2H4SSeSC2H4SS)n, with randomly distributed —SSeS— and —SS— moieties. The reaction in water produces incompletely reacted material, which on recrystallization, gives an oligomer corresponding to 5 EDT units (pentamer) as confirmed by molecular mass determination, Se analysis, 1H- and 77Se-NMR spectroscopy. In both the pentamer and cyclic forms the incidence of neighboring —SSeS— moieties is higher than that expected statistically. The mechanism for the reaction of thiols with selenous acid provides some rationalization for this observation in as much as neighboring —SSeS— groups, or groups that will lead rapidly to neighboring —SSeS— groups are formed in general before —SS— links can be formed. The Raman spectrum of these products show typical strong SS, SeS, and CS stretching bands at 510, 370, and 730 cm-1. The high frequency of νCS is attributed to a preferred gauche conformation at the CS bonds. For comparison, polydisulfides were also prepared from EDT and iodine in methanol. These products consist of at least seven cyclic polymers ranging from the four-membered 1,2-dithietane to higher members. Heating above 100°C in chloroform for several hours gives a solution containing the four lowest molecular mass rings, which on standing for 24 h, precipitate highly insoluble material, which is probably chain or large-ring polymer. Molecular mass determination in camphor indicates that, like yellow sulphur, chain polymers are formed at the melting point of camphor (170°C). © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 379-390, 1998
    Zusätzliches Material: 6 Ill.
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  • 240
    Digitale Medien
    Digitale Medien
    Synthesis of polyurethane from cashew nut shell liquid (CNSL), a renewable resource (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 391-400 
    Details
    ISSN: 0887-624X
    Schlagwort(e): cardanol ; polyurethane ; thermoplastic polyurethane ; differential scanning calorimetry ; dynamic mechanical thermal analyzer ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A novel thermoplastic polyurethane was prepared from cardanol, a renewable resource and a waste of the cashew industry. Cardanol was recovered from cashew nut shell liquid (CNSL) by double vacuum distillation. It was characterized by CHN analysis and IR, 1H-NMR, and 13C-NMR spectroscopy techniques. Cardanol is a meta-substituted long chain phenol. The long aliphatic chain unit substituent was found to be a monoene. The monomer, 4-[(4-hydroxy-2-pentadecenylphenyl)diazenyl]phenol was prepared from cardanol. It was a dihydroxy compound as characterized by CHN analyzer, UV, and 1H-NMR spectroscopy. The polyurethane was synthesized from this dihydroxy compound by the treatment with 4,4′-diphenylmethane diisocyanate (MDI) in dimethylformamide (DMF) solvent at 80-90°C under nitrogen atmosphere. The polymer was characterized by 1H-NMR, FTIR, and UV spectroscopy. The elemental analysis was done for determining the percentage content of C, H, and N, and the intrinsic viscosity [η] of polymer showed 1.85 dL/gm. Thermogravimetric investigations (TGA) of the cardanol, the dihydroxy compound, and the polyurethane were performed to study their decomposition. The semicrystalline nature of the PU was confirmed by differential scanning calorimetry (DSC) and dynamic mechanical thermal analyzer (DMTA). The wide-angle X-ray diffraction (WAXS) study of PU shew a broad amorphous halo indicative of absence of crystallinity in the polymer, which has been explained as due to strong hydrogen bonding in the hard phase. PU may possibly be useful as a telecommunication and as a nonlinear optical material. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 391-400, 1998
    Zusätzliches Material: 11 Ill.
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  • 241
    Digitale Medien
    Digitale Medien
    Synthesis and properties of polyamides with [60]fullerene in the main chain (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 3139-3146 
    Details
    ISSN: 0887-624X
    Schlagwort(e): [60]fullerene ; polyamide ; conjugation ; cyclopropane ring ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A novel series of polyamides having [60]fullerene moieties in the main chain were synthesized by a direct polycondensation of [60]fullerenobis(acetic acid) or [60]fullerenobis(acetic acid)/isophthalic acid mixture with a diamine in the presence of triphenyl phosphite and pyridine. Various properties of the polyamides were characterized by means of IR, GPC, TGA, DSC, UV-visible, and photoluminescence. The molecular weight Mw of the [60]fullerene-containing polyamides was observed in the range from about 300,000 to 3,000; upon the changing of the ratio of [60]fullerenobis(acetic acid)/isophthalic acid in the starting mixture, the resulting Mw decreased with increasing the ratio. Most of the thermal and optical properties gradually changed as the ratio changed; the major optical absorption band in visible range exhibited a significant tailing, which shifted toward a longer wavelength, while the photoluminescence spectrum red-shifted with increasing [60]fullerene content. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 3139-3146, 1998
    Zusätzliches Material: 8 Ill.
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  • 242
    Digitale Medien
    Digitale Medien
    Application of solid-state NMR (13C and 29Si CP/MAS NMR) spectroscopy to the characterization of alkenyltrialkoxysilane and trialkoxysilyl-terminated polyisoprene grafting onto silica microparticles (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 437-453 
    Details
    ISSN: 0887-624X
    Schlagwort(e): functionalized silica ; functional polyisoprene ; grafting onto silica ; polyisoprene-grafted silica ; alkenyl-bonded silica ; 13C and 29Si CP/MAS NMR ; grafting characterization ; surface characterization ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The solid-state Nuclear Magnetic Resonance (NMR) was used to characterize surfaces of silica gels chemically modified by alkenyltrialkoxysilanes and trialkoxysilyl terminated 1,4-polyisoprenes. The formation of covalent bonds created between alkoxy functional groups from alkenyltrialkoxysilane or trialkoxysilyl-terminated 1,4-polyisoprene and silanol groups on silica was clearly demonstrated by means of 13C and 29Si CP/MAS NMR spectroscopy. Quantitative data, including calculation of the grafting yields in relation with the initial silanol concentrations, were also obtained by using solid-state 29Si-NMR leading to a final well-defined characterization of the silica surfaces. A relatively good agreement was noticed between the grafting yields calculated from 29Si-NMR spectra and those determined from other analytical techniques such as Wijs titration or elementary analysis. The reactivity of the various silica silanols towards each coupling agent was clearly characterized and estimated, as were the proportions of the various grafted structures formed at the silica surface. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 437-453, 1998
    Zusätzliches Material: 6 Ill.
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  • 243
    Digitale Medien
    Digitale Medien
    A study of the thermal cure of a phenylethynyl-terminated imide model compound and a phenylethynyl-terminated imide oligomer (PETI-5) (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 461-470 
    Details
    ISSN: 0887-624X
    Schlagwort(e): kinetics ; polyimides ; thermal cure ; infrared spectroscopy ; DSC ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The kinetic mechanism of the thermal cure of a phenylethynyl-terminated imide model compound, 3,4′-bis[(4-phenylethynyl)phthalimido]diphenyl ether (PEPA-3,4′-ODA) and a phenylethynyl-terminated imide oligomer PETI-5 (MW 5000 g/mol) was studied. FTIR was used to follow the cure of the model compound, while thermal analyses (DSC) was used to follow the cure of the PETI-5 oligomer. The changes in IR absorbance of phenylethynyl triple bonds at 2214 cm-1 of PEPA-3,4′-ODA as a function of cure time were detected at 318, 336, 355, and 373°C, respectively. The changes in the glass transition temperature, Tg, of PETI-5 as a function of time were measured at 350, 360, 370, 380, and 390°C, respectively. The DiBenedetto equation was applied to define the relative extent of cure, x, of the PETI-5 oligomer by Tg. For the model compound, the reaction followed first order kinetics, yielding an activation energy of 40.7 kcal/mol as determined by infrared spectroscopy. For PETI-5, the reaction followed 1.5th order, yielding an activation energy of 33.8 kcal/mol for the whole cure reaction, as determined by Tg using the DiBenedetto method. However, the cure process of PETI-5 just below 90% by this method followed first-order kinetics yielding an activation energy of 37.2 kcal/mol. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 461-470, 1998
    Zusätzliches Material: 13 Ill.
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  • 244
    Digitale Medien
    Digitale Medien
    Effect of reaction conditions on synthesis and properties of multiarm star-branched polyisobutylenes (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 471-483 
    Details
    ISSN: 0887-624X
    Schlagwort(e): Multiarm star-branched polyisobutylenes ; reaction conditions ; synthesis ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A series of multiarm star-branched polyisobutylenes was synthesized from narrow polydispersity arms with molecular weights ranging from 12,000 to 60,000 g/mol, via living carbocationic polymerization using the cumyl chloride/TiCl4/pyridine initiating system and divinylbenzene (DVB) as core-forming comonomer. The effect on star development of arm molecular weight, temperature, solvent composition, and DVB concentration was studied. The rate of star formation and the weight-average number of arms per star polymer, N̄w, were found to scale inversely with arm molecular weight; N̄w = 60 was attained for 13,100 g/mol arms, but N̄w = 2.5 for 60,000 g/mol arms. It was established that star formation was much faster at -80°C compared to 23°C, regardless of solvent composition. For hexane : methyl chloride (MeCl) solvent compositions containing from 40 to 60 vol % MeCl, star-star coupling was observed at -80°C, but not at 23°C, even after 312 h; for the most polar 40 : 60 hexane : MeCl composition, star-star coupling was so extensive at -80°C that gelation was observed after only 44 h. The rate of star formation was found to be substantially higher in 60 : 40 hexane : MeCl compared to 60 : 40 hexane : methylene chloride (MeCl2). Some reactions containing MeCl were immediately warmed to 23°C after DVB addition, and the MeCl thus volatilized was replaced with either MeCl2 or hexane for the duration of the star-forming reaction. Slightly higher rates were consistently observed when MeCl2 was the replacement solvent. The strong influence of initial MeCl content on rate of star formation was found to persist throughout the star-forming reaction, even when the solvent was immediately converted to 100% hexane. The fraction of arms that remained unlinked into stars was found to be higher at the higher temperature and at lower solvent polarity. Regardless of solvent or temperature, the residual arm fraction was approximately the same at a given stage of star development as measured by the average number of arms per star. One star sample was produced with the UV-transparent 2-chloro-2,4,4-trimethylpentane initiator; analysis showed that the residual arm fraction had approximately the same UV absorbance as the star fraction, indicating efficient crossover to DVB and the potential for approximately quantitative arm incorporation given sufficient time. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 471-483, 1998
    Zusätzliches Material: 10 Ill.
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  • 245
    Digitale Medien
    Digitale Medien
    Synthesis and properties of polyimides from thianthrene-2,3,7,8-tetracarboxylic dianhydride-5,5,10,10-tetraoxide (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 485-494 
    Details
    ISSN: 0887-624X
    Schlagwort(e): thianthrene-tetraoxide ; polyimide ; synthesis ; membrane ; CO2 gas separation ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Thianthrene - 2,3,7,8 - tetracarboxylic dianhydride - 5,5,10,10 - tetraoxide (TADATO), a dianhydride having two sulfonyls between two phenyl rings, was synthesized and polymerized with several diamines by a two-step method. Tough polyimide membranes were obtained with flexible diamines but not with rigid diamines. Most of TADATO-based polyimides are soluble in polar solvents such as N,N-dimethylacetamide and N-methyl-2-pyrrolidone. IR study confirmed that almost complete imidization of TADATO-based poly(amic acid) membranes could be achieved by thermal treatment at 100, 200, and 300°C for each 1 h. In a series of polyimides based on 4,4′-oxydianiline, the polyimide from TADATO showed higher gas permeability coefficient of CO2 and higher selectivities of CO2/N2 and CO2/CH4 than those of polyimides from pyromellitic dianhydride and 3,3′,4,4′-biphenyltetracarboxylic dianhydride, and was comparable to that from 2,2-bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 485-494, 1998
    Zusätzliches Material: 6 Ill.
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  • 246
    Digitale Medien
    Digitale Medien
    Preparation and characterization of thermoresponsive isopropylacrylamide-hydroxyethylmethacrylate copolymer gels (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 527-541 
    Details
    ISSN: 0887-624X
    Schlagwort(e): isopropylacrylamide ; hydroxyethylmethacrylate ; thermoresponsive gel ; stimuli-responsive polymer ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A random copolymer of N-isopropylacrylamide and 2-hydroxyethylmeth-acrylate, poly(NIPAM-co-HEMA), having thermoresponsive character was prepared bya redox copolymerization method. Poly(ethylene glycol), PEG 4000 was included in the copolymerization recipe to increase the thermoresponsivity of copolymeric structure. Poly(NIPAM-co-HEMA) copolymer gels having more elastic character and higher mechanical strength relative to poly(NIPAM) gel could be achieved by the proposed copolymerization procedure. The equilibrium and dynamic response against the temperature were investigated for the gel matrices produced by changing the initial NIPAM/HEMA mol ratio and PEG 4000 concentration in the copolymerization mixture. The effective diffusion coefficient of water within the gel matrix was estimated for either swollen or shrunken states by applying an unsteady-state diffusion model on the dynamic swelling and shrinking behaviors of gel matrix prepared in the cylindrical form. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 527-541, 1998
    Zusätzliches Material: 11 Ill.
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  • 247
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    Digitale Medien
    Kinetic model-based experimental design of the polymerization conditions in suspension copolymerization of styrene/divinylbenzene (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2081-2094 
    Details
    ISSN: 0887-624X
    Schlagwort(e): copolymerization ; crosslinking ; polystyrene-divinylbenzene ; experimental designs ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The use of a mechanistic model-based experimental design technique to determine the polymerization conditions and polymer properties in suspension copolymerization of styrene and divinylbenzene is reported. The technique consists of using a mathematical model to design the polymerization conditions of a copolymer with characteristics specified beforehand. The properties (conversion, gel content, molecular weight averages, and copolymer composition) of the copolymer synthesized using this approach agree very well with the calculated properties for the pregelation period, but accurate prediction of properties during the postgelation period is still uncertain. It is demonstrated that the use of mechanistic modeling for experimental design purposes can be more adequate (when the model is sound, yet simple to solve) than other design techniques (e.g., factorial designs). © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2081-2094, 1998
    Zusätzliches Material: 9 Ill.
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  • 248
    Digitale Medien
    Digitale Medien
    Polymerization of styrene with nickel complex/methylaluminoxane catalytic systems (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2119-2126 
    Details
    ISSN: 0887-624X
    Schlagwort(e): stereospecific polymerization ; isotactic polystyrene ; nickel catalysts ; methylaluminoxane ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Polymerization of styrene using catalytic systems based on nickel derivatives and methylaluminoxane (MAO) was studied. Among tested catalysts, nickel bis(acetylacetonate) and nickel dichloride show the maximum activity. Bis(phosphine)nickel dichlorides exhibit lower activity, depending on the nature of the phosphine ligand. Polymer yields decrease by lowering the catalyst concentration, by increasing the reaction temperature, or by carrying out the polymerization in a polar donor solvent. Weight average molecular weight of most of the prepared polystyrenes ranges from 9000 to 25,000, with polydispersity indexes of 1.6-3.8. However, polystyrene prepared in dioxane solvent exhibits a small fraction of very high molecular weight (about 140,000). From NMR analysis, the products seem generally to be constituted of two polymers with different steric microstructure: atactic polystyrene and partially isotactic polystyrene (ca. 75-85% meso diads). Catalytic site specificity is correlated with the type of nickel ligand, while the effect of reaction temperature is less defined. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2119-2126, 1998
    Zusätzliches Material: 1 Ill.
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  • 249
    Digitale Medien
    Digitale Medien
    A versatile and efficient synthesis of alkoxyamine LFR initiators via manganese based asymmetric epoxidation catalysts (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2161-2167 
    Details
    ISSN: 0887-624X
    Schlagwort(e): alkoxyamine ; living free radical polymerizations ; asymmetric epoxidation ; Jacobsen's catalyst ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: No abstract.
    Zusätzliches Material: 1 Tab.
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  • 250
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    Digitale Medien
    Synthesis and characterization of new polyamides derived from 1,6-bis[4-(4-aminophenoxy)phenyl]diamantane (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2185-2192 
    Details
    ISSN: 0887-624X
    Schlagwort(e): high-temperature polyamide ; diamantane ; characterization ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A series of new polyamides 3 were synthesized by direct polycondensation of the 1,6-bis[4-(4-aminophenoxy)phenyl]diamantane (1) with various dicarboxylic acids. The polyamides had inherent viscosities of 0.45-1.90 dL/g and number-average molecular weights (Mn) of 24,000-110,000. Dynamic mechanical analysis (DMA) reveals that polymers 3 have two relaxations on the temperature scale between -100 and 400°C. Their α relaxations occurred at high temperatures, ranging from 338 to 389°C. Moreover, these polymers remained quite stable at high temperatures and maintained good mechanical properties (G′ = ca. 108 Pa) up to temperatures close to the main transition markedly exceeding 350°C. Due to the bulky diamantane elements and the flexible ether segments, the polymers 3 were amorphous and soluble in a number of organic solvents such as pyridine, N-methyl-2-pyrrolidone (NMP), and N,N-dimethylacetamide (DMAc). The polyamides 3 have tensile strengths of 56.7-90.2 MPa, elongation to breakage values of 7.5-27.7%, and initial moduli of 1.8-2.1 GPa. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2185-2192, 1998
    Zusätzliches Material: 4 Ill.
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  • 251
    Digitale Medien
    Digitale Medien
    Synthesis of ordered polymer by direct polycondensation. VIII. Ordered polymer from two nonsymmetric monomers (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2309-2314 
    Details
    ISSN: 0887-624X
    Schlagwort(e): direct polycondensation ; ordered polymer ; polyamide ; condensing agent ; steric effect ; nonsymmetric monomer ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The ordered (-aacdbbdc-) polymer was prepared by the direct polycondensation of a pair of symmetric monomers (XabX), 4,4′-(oxydi-p-phenylene)dibutanoic acid (XaaX) and 2-methoxyisophthalic acid (XbbX), with a nonsymmetric monomer (YcdY), 4-aminobenzhydrazide, using the condensing agent diphenyl (2,3-dihydro-2-thioxo-3-benzoxazolyl)phosphonate (1). The polymerization was carried out by a one-pot procedure, that is, mixing the dicarboxylic acids, condensing agent 1 and triethylamine in NMP for 2 h at room temperature, followed by the addition of 4-aminobenzhydrazide. This polymerization proceeded smoothly, yielding the ordered polymer with an inherent viscosity of 0.34 dL g-1. The microstructure of the ordered polymer was confirmed by comparing the authentic ordered polymer in their 13C-NMR spectrum. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2309-2314, 1998
    Zusätzliches Material: 3 Ill.
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  • 252
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    Digitale Medien
    Polyesters containing sulfur. VI. Synthesis and characterization of polyesters from naphthalene-1,4- or naphthalene-1,5-bis(methylthioacetic acid) and aliphatic diols (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2359-2369 
    Details
    ISSN: 0887-624X
    Schlagwort(e): linear polyesters containing sulfur ; melt polycondensation ; kinetic parameter ; thermoplastic polyurethane elastomers ; melt polyaddition ; physicochemical and tensile properties ; thermal behavior ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Two series of new linear polyesters containing sulfur in the main chain were obtained by melt polycondensation of naphthalene-1,4-bis(methylthioacetic acid) (N-1,4-BMTAA) or naphthalene-1,5-bis(methylthioacetic acid) (N-1,5-BMTAA) with some aliphatic diols using a 0.05 molar excess of diol. Softening temperatures ranging from 55 to 130°C, reduced viscosities in the range of 0.15-0.39 dL/g, and low-molecular weights were their characteristic. The structure and thermal properties of all polyesters were examined by using elemental analysis, FT-IR and 1H-NMR spectroscopy, X-ray diffraction analysis, differential thermal analysis (DTA), thermogravimetric analysis (TGA), and differential scanning calorymetry (DSC). The kinetics of polyester formation by uncatalyzed melt polycondensation was studied in a model system: N-1,4-BMTAA or N-1,5-BMTAA and 2,2′-oxydiethanol (ODE) at 150, 160, and 170°C. Reaction rate constants (k3) and activation parameters (ΔG
    Zusätzliches Material: 9 Ill.
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  • 253
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    Digitale Medien
    Studies on metathetical and thermal polymerization of 5-norbornene 2,3-dicarboximide end-capped resins pt-II (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2427-2427 
    Details
    ISSN: 0887-624X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 1 Ill.
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  • 254
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    Digitale Medien
    Synthesis and characterization of side-chain liquid-crystalline poly(ether ester)s having p-substituted biphenyl mesogenic side groups (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2439-2455 
    Details
    ISSN: 0887-624X
    Schlagwort(e): spiro-orthoester monomers ; poly(ether ester)s ; cationic ring-opening polymerization ; side-chain liquid-crystalline polymers ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Several novel mesogenic spiro-orthoester monomers such as 1,6,10-trioxaspiro[4,5]decanes 4, containing biphenyl mesogens at the C-8 positions of the five- and six-membered spirocyclic ring, through the alkylene spacers of different lengths were prepared by condensation reaction of the corresponding biphenyl mesogenic 1,3-propanediol 3 with 2,2-diethoxytetrahydrofuran, with 50-75% yields. Through cationic double ring-opening polymerization, carried out with boron trifluoride etherate as an initiator (5 mol % vs. monomer) in bulk at 150°C, spiro-orthoester monomers 4 afforded a novel class of side-chain thermotropic LC polymers with a poly(ether ester) as the main chain 8. The liquid-crystalline properties of the spiro-orthoester monomers and the resulting polymers were examined by differential scanning calorimetry and optical polarized microscopy. Biphase separation was observed in the side-chain liquid-crystalline poly(ether ester)s upon annealing in the broad isotropic region. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2439-2455, 1998
    Zusätzliches Material: 20 Ill.
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  • 255
    Digitale Medien
    Digitale Medien
    Production of micron-sized monodispersed polymer particles by seeded polymerization for the dispersion of highly monomer-swollen particles prepared with submicron-sized polymer seed particles utilizing the dynamic swelling method (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2513-2519 
    Details
    ISSN: 0887-624X
    Schlagwort(e): dynamic swelling method ; particle ; monodisperse ; micron-size ; seeded polymerization ; emulsion polymerization ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: For the purpose of extending the size range of polymer seed particles used in “dynamic swelling method” (DSM), first it was verified theoretically that the submicron-sized polymer particles produced by emulsion polymerization can also absorb a large amount of monomer by DSM in both equilibrium and kinetic control states. Next, on the basis of the theoretical results, experimentally about 2.6 μm-sized styrene-swollen polystyrene (PS) particles were prepared utilizing DSM in the presence of 0.64 μm-sized monodispersed PS seed particles produced by emulsifier-free emulsion polymerization. Moreover, 2.5 μm-sized monodispersed PS particles were produced by the addition of cupric chloride as a water-soluble inhibitor to depress the by-production of submicron-sized PS particles in the seeded polymerization at 30°C with 2,2′-azobis(4-methoxy-2,4-dimethylvaleronitrile) initiator. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2513-2519, 1998
    Zusätzliches Material: 11 Ill.
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  • 256
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    Digitale Medien
    Tributylstannylated silicic acid as precursor of organofunctionalized silica gel (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 655-663 
    Details
    ISSN: 0887-624X
    Schlagwort(e): water glass ; bis(tributyltin)oxide ; tributylstannylated silicic acid ; functionalized silica gel ; silane coupling agent ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Tributylstannylated silicic acid (TBSA), which was regarded as a protected polymeric silanol against self-condensation to give silica gel, was newly prepared from the reaction of water glass (WG) and bis(tributyltin) oxide (TBO). The ratios of Si/Sn contained in TBSA were determined by gravimetric analysis to be in the range of 2-3. The gelation of TBSA in usual organic solvents such as hexane, benzene, and dichloromethane was not observed over 3 weeks. In addition, TBSA was shown to be a convenient precursor for the preparations of silica gel modified with organofunctional groups. From the reaction of TBSA with trimethoxysilanes and aromatic alcohols, the silica gels havingorganofunctional groups were obtained with the elimination of a tributyltin group. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 655-663, 1998
    Zusätzliches Material: 5 Ill.
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  • 257
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    Digitale Medien
    Convenient approach to novel functional substituted and branched poly(silylenemethylenes) (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 725-735 
    Details
    ISSN: 0887-624X
    Schlagwort(e): organosilicon polymer ; poly(silylenemethylene) ; silyl triflate ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Novel poly(silylenemethylenes) have been prepared by the ring-opening polymerization of 1,3-disilacyclobutanes followed by a protodesilylation reaction with triflic acid. The silicon-aryl bond cleavage could be controlled by using different leaving groups, for instance phenyl- and para-anisyl substituents. The reactions of the triflate derivatives with organomagnesium compounds, LiAlH4, amines, or alcohols gave functional substituted poly(silylenemethylenes). Hydrosilylation reactions or reductive coupling with potassium-graphite led to organosilicon network-polymers, which may serve as suitable precursors for silicon carbide and Si/C/N-based materials. The structures of the polymers were identified by NMR spectroscopy (29Si, 13C, 1H). © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 725-735, 1998
    Zusätzliches Material: 5 Ill.
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  • 258
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    Digitale Medien
    Synthesis of poly(hydroxymethylene-co-ethylene) by hydrogenation of the ethylene and carbon monoxide copolymer obtained by radical initiator with Ru/α-alumina and oxygen gas permeability (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 889-900 
    Details
    ISSN: 0887-624X
    Schlagwort(e): hydrogenation ; α-alumina support ; Ru metal ; amine ; water ; polyalcohol ; ethylene CO copolymer ; radical initiator ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A new polymer (polyalcohol) was synthesized by hydrogenation of an ethylene carbon monoxide (CO) copolymer produced by a radical method with a catalyst and H2. The Ru/α-alumina catalyst systems showed an excellent activity for hydrogenation of the radical copolymer of CH2=CH2 and CO. Films prepared by melting and pressing the synthesized polyalcohol had a high gas barrier property and high tensile modulus. This new polymer has hydroxymethylenic units [—CH(OH)—] and ethylenic units [—CH2CH2—] in its molecular structure. The new functional polymer poly(hydroxymethylene-co-ethylene), —[—CH(OH)—]n[—CH2CH2—]m—, is amorphous and has excellent and important properties as a high oxygen gas barrier film for wrapping and storage. This may be attributed to the new structure of poly(hydroxymethylene-co-ethylene) (PHME as an IUPAC name), or ethylene methine alcohol copolymer (EMOH as a generic name), compared to the other ethylene vinyl alcohol copolymer (EVOH as a generic name), —[—CH2CH2—]m—[—CH2CH(OH)—]n—, which is used as one of the highest gas barrier polymers. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 889-900, 1998
    Zusätzliches Material: 6 Ill.
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  • 259
    Digitale Medien
    Digitale Medien
    Effect of substituents on the curing of liquid crystalline epoxy resin (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 911-917 
    Details
    ISSN: 0887-624X
    Schlagwort(e): liquid crystalline epoxy resin ; substitution ; curing ; network ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The synthesis of an aromatic ester based liquid crystalline epoxy resin (LCE) with a substituent in the mesogenic central group is described. Chlorine and methyl groups were introduced as substituents. The curing behaviors of three epoxy resins were investigated using diaminodiphenyl ester as the curing agent. The curing rate and heat of curing of LCE were measured with dynamic and isothermal DSC. The chlorine substituent accelerated the curing of LCE, while the methyl substituent decelerated the curing of LCE. The heat of curing of substituted LCE was diminished compared to LCE with no substituent. Glass transition temperature and elastic modulus of LCE decreased with increasing the size of the substituent. Three liquid crystalline epoxy resins based on aromatic ester mesogenic groups formed a liquid crystalline phase after curing, and the liquid crystalline phase was stable up to the decomposition temperature. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 911-917, 1998
    Zusätzliches Material: 7 Ill.
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  • 260
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    Digitale Medien
    New poly(amide-imide) syntheses. XXI. Synthesis and properties of aromatic poly(amide-imide)s based on 2,6-bis(4-trimellitimidophenoxy)naphthalene and aromatic diamines (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 919-927 
    Details
    ISSN: 0887-624X
    Schlagwort(e): poly(amide-imide)s ; direct polycondensation ; 2,6-bis(4-aminophenoxy)naphthalene ; 2,6-bis(4-trimellitimidophenoxy)naphthalene ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A novel polymer-forming diimide-diacid, 2,6-bis(4-trimellitimidophenoxy)naphthalene, was prepared by the condensation reaction of 2,6-bis(4-aminophenoxy)naphthalene with trimellitic anhydride (TMA). A series of novel aromatic poly(amide-imide)s containing 2,6-bis(phenoxy)naphthalene units were prepared by the direct polycondensation of the diimide-diacid with various aromatic diamines using triphenyl phosphite (TPP) in N-methyl-2-pyrrolidone (NMP)/pyridine solution containing dissolved calcium chloride. Thirteen of the obtained polymers had inherent viscosities above 1.01 dL/g and up to 2.30 dL/g. Most of polymers were soluble in polar solvents such as DMAc and could be cast from their DMAc solutions into transparent, flexible, and tough films. These films had tensile strengths of 79-117 MPa, elongation-at-break of 7-61%, and initial moduli of 2.2-3.0 GPa. The wide-angle X-ray diffraction revealed that some polymers are partially crystalline. The glass transition temperatures of some polymers could be determined with the help of differential scanning calorimetry (DSC) traces, which were recorded in the range 232-300°C. All the poly(amide-imide)s exhibited no appreciable decomposition below 450°C, and their 10% weight loss temperatures were recorded in the range 511-577°C in nitrogen and 497-601°C in air. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 919-927, 1998
    Zusätzliches Material: 1 Ill.
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  • 261
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    Digitale Medien
    Preparation and properties of processable polyimides having bulky pendent ether groups (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 971-978 
    Details
    ISSN: 0887-624X
    Schlagwort(e): processable polyimide ; bulky pendent ether groups ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A series of aromatic diamines containing pendent methoxy, phenoxy, and biphenoxy moieties were synthesized. By the reaction of diamines with 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BTDA), several kinds of polyimides having bulky pendent ether groups were synthesized. Thermal properties and processability such as melt processability and solubility in organic solvents of obtained polyimides were investigated by focusing on the chemical structures of their repeating structure units. It was found that the thermal stability and melt processability of the polyimides did not strongly depend on the existence of bulky pendent phenoxy and biphenoxy moieties. Their solubility in organic solvents, however, was improved by introducing the bulky pendent ether groups such as methoxy, phenoxy, and biphenoxy moieties into their repeating structure units. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 971-978, 1998
    Zusätzliches Material: 1 Ill.
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  • 262
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    A new direct preparation of electroconductive polyimide/carbon black composite via polycondensation of nylon-salt-type monomer/carbon black mixture (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1031-1034 
    Details
    ISSN: 0887-624X
    Schlagwort(e): electroconductive polymer ; polyimide-carbon black composite ; direct polycondensation ; salt monomer method ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: No abstract.
    Zusätzliches Material: 3 Ill.
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  • 263
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    Synthesis and properties of poly(oxyethylene)s containing thioether, sulfoxide, or sulfone groups (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 793-801 
    Details
    ISSN: 0887-624X
    Schlagwort(e): poly(oxyethylene) ; thioether ; sulfoxide ; sulfone ; copolymer ; solubility ; glass transition temperature ; substitution ; oxidation ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Poly[oxy(ethylthiomethyl)ethylene] (ETE) was prepared from poly[oxy (chloromethyl)ethylene] (CE) by reaction with sodium ethanethiolate. Sulfoxide and sulfone analogues were synthesized by oxidation of the poly[oxy(ethylthiomethyl)ethylene]. By changing the chloromethyl/sodium ethanethiolate ratio, poly[oxy (chloromethyl)ethylene-co-oxy(ethylthiomethyl)ethylene] (CE-ETEs) were easily made. Poly[oxy(ethylsulfinylmethyl)ethylene] (ESXE), poly[oxy(chloromethyl)ethylene-co-oxy(ethylsulfinylmethyl)ethylene] (CE-ESXEs), poly[oxy(ethylsulfonylmethyl)ethylene] (ESE), and poly[oxy(chloromethyl)ethylene-co-oxy(ethylsulfonylmethyl)ethylene] (CE-ESEs) were obtained by oxidation of ETE or CE-ETEs. There was little if any chain degradation. The (co)polymer structures were confirmed by FTIR and 1H-NMR spectroscopic studies. Their thermal properties were studied by DSC and TGA. Tgs of ETE, ESXE, and ESE were -57, 36, and 57°C, respectively, and Td,os (initial decomposition temperature, TGA) were 331, 198, and 308°C, respectively. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 793-801, 1998
    Zusätzliches Material: 7 Ill.
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  • 264
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    Graft copolymers prepared by ethoxylation of polyamide 12 and poly(ethylene-co-vinyl alcohol) (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 803-811 
    Details
    ISSN: 0887-624X
    Schlagwort(e): grafting ; poly(amide-graft-ethylene oxide) ; poly(ethylene-co-vinyl alcohol-graft-ethylene oxide) ; ethoxylation ; anionic polymerization of ethylene oxide ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Graft copolymers consisting of polyamide 12 or poly(ethylene-co-vinyl alcohol) as backbone polymers and side chains of poly(ethylene oxide) have been synthesized. The amide and hydroxyl groups of the backbone polymers were used as initiation sites for the polymerization of ethylene oxide (EO). Potassium tert-butoxide was used for ionization of the active groups, and the polymerization of EO was carried out in dimethyl sulfoxide. The graft copolymers were characterized with respect to molecular weight and composition using elemental analysis, 1H-NMR, gel permeation chromatography, and FTIR. The size of the side chains varied between 300 and 1000 g/mol. Thermal properties were examined by DSC. The graft copolymers showed increasing crystallinity and increasing melt temperature with increasing molecular weight of the side chains. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 803-811, 1998
    Zusätzliches Material: 7 Ill.
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  • 265
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    Comments on the determination of absolute rate constants in anionic polymerization (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1065-1068 
    Details
    ISSN: 0887-624X
    Schlagwort(e): anionic polymerization ; absolute rate constants ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Claims have recently been made that absolute rate constants for chain propagation of the unassociated active centers can be made in systems where a high degree of association is present. Anionic polymerization of styrene in nonpolar solvents with lithium as counterion is a typical case. The conditions required to obtain these constants (and the associated aggregate dissociation constants) are described using data from styrene polymerization with lithium and potassium as counterions and data from o-methoxystyrene polymerization. The conclusion reached must be that the kp and Kds values obtained for styrene with counterion lithium cannot be obtained from existing literature data and are simply artifacts of the computer analysis. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1065-1068, 1998
    Zusätzliches Material: 2 Ill.
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  • 266
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    Synthesis and characterization of poly(aryl ether)s containing the pyrimidine moiety (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1107-1110 
    Details
    ISSN: 0887-624X
    Schlagwort(e): poly(aryl ether)s ; pyrimidine ; thermostability ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A series of new poly(aryl ether)s containing the pyrimidine moiety were prepared by a nucleophilic aromatic substitution polymerization reaction in an aprotic solvent (DMAc) in the presence of excess potassium carbonate. These polymers are high molecular weight, amorphous, and soluble in common solvents at room temperature. The polymers are easily cast from solution into flexible, colorless, and transparent films. They showed high glass transition temperatures ranging from 198 to 304°C by DSC analysis. The 5% weight losses by thermogravimetric analysis ranged from 478 to 580°C, indicating that these polymers are very thermostable in nitrogen and air. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1107-1110, 1998
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  • 267
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    A theoretical study of the comonomer effect in the ethylene polymerization with zirconocene catalytic systems (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1157-1167 
    Details
    ISSN: 0887-624X
    Schlagwort(e): zirconocene catalysts ; ethylene ; 1-hexene ; copolymerization ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The PM3(tm) semiempirical method has been used to optimize the structures for the reactants and transition states of the first and second ethylene insertion processes into zirconocene catalytic systems. The results obtained for these reactions are compared with calculations published in the literature performed at different ab-initio theoretical levels. The agreement between our calculations and those reported in the literature is satisfactory. Taking advantage of the reduced computational effort required in semiempirical calculations two additional processes related with the so-called comonomer effect were also studied: ethylene/1-hexene copolymerization, and chain termination reaction, both in the homopolymerization and in copolymerization of ethylene with 1-hexene comonomer. The calculated activation energies support some experimental findings such as the higher polymerization activities in the presence of comonomers and also the molecular weight reduction of the copolymers due to the more favorable β-elimination reactions. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1157-1167, 1998
    Zusätzliches Material: 3 Ill.
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  • 268
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    Ionic and excited intermediates in pulse-irradiated polypropylene doped with aromatics (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1217-1226 
    Details
    ISSN: 0887-624X
    Schlagwort(e): polypropylene ; pyrene ; two-solute system ; pulse radiolysis ; solute ionic species ; solute excited states ; low-temperature radiolysis ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A pulse radiolysis study of isotactic polypropylene (PP) film has been carried out with the main aims of investigating charge trapping in an undoped system and solute radical ion generation in an pyrene (Py) doped matrix. In PP, pulse radiolysis gives electron-positive hole pairs. The electron can be stabilized in the undoped system as a trapped electron, et-. The transient absorption spectrum of et- in the near-IR (up to 1800 nm) was observed in the temperature range 30-100 K. This IR absorption was not detected in the case of oxidized PP. In such a matrix electrons can be scavenged by oxidation products generating respective radical-anions (absorption in the UV RANGE, λ 〈 350 nm). In a doped matrix transient absorption bands centered at 450 and 500 nm were observed which can be assigned to the Py radical cation and anion, respectively. The recombination of these ionic species leads to monomer excited-state formation observed during and after the 17 ns pulse. Contrary to the Py-doped polyethylene no excimer emission was detected at room temperature even if Py content in PP was close to 0.02 mol dm-3. The rate of Py radical-ion decay was found to be temperature dependent. Two linear parts of the Arrhenius plot were observed which intersected at ca. 240 K, the glass transition temperature, Tg, for PP. The activation energies calculated for two parts of Arrhenius plot were equal to 111 and ca. 0.78 kJ mol-1 for T 〉 Tg and T 〈 Tg, respectively. Some preliminary results concerning the ionic processes in PP containing two solutes (Py, 3,3′-dimethyldiphenyl) were presented. The mechanism of ionic recombination in PP will be proposed and discussed. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1217-1226, 1998
    Zusätzliches Material: 7 Ill.
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  • 269
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    Synthesis of acid-functional asymmetric aliphatic polyesters (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1345-1348 
    Details
    ISSN: 0887-624X
    Schlagwort(e): acid functional ; telechelic ; benzyl alcohol ; poly(ε-caprolactone) ; polymerization ; living ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 2 Ill.
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  • 270
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    Preparation and absorption spectrum studies of aromatic and alicyclic poly(amide acid) ammonium salts in water and DMF and in films (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1329-1340 
    Details
    ISSN: 0887-624X
    Schlagwort(e): poly(amide acid) ammonium salts ; poly(amide acid)s ; water-soluble polyimide precursors ; UV-vis absorption spectra ; charge transfer ; solubility ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A series of ammonium salts of poly(amide acid)s (PAS) were prepared from various poly(amide acid)s (PAA) with tertiary amines. The solubility of poly(amide acid) ammonium salts prepared from PAA(PMDA/ODA) in water is related to the ion concentration of tertiary amines. In order to elucidate the influence of the chemical structures of poly(amide acid)s and poly(amide acid) ammonium salts on their absorption spectra, pyromellitic dianhydride (PMDA), 3,3′,4,4 ′-biphenyltetracarboxylic dianhydride (BPDA), and 3,3′,4,4 ′-benzophenonetetracarboxylic dianhydride (BTDA) were chosen to react with p-phenylenediamine (PDA) and (4,4′-diaminodicyclohexyl)methane (DCHM) to give three kinds of aromatic PAAs and three kinds of alicyclic PAAs. The corresponding PASs were prepared by the reaction of PAAs with triethanolamine (TEA). Their ultraviolet-visible (UV-vis) absorption spectra were investigated compared to those of model compounds. A transparent film without absorption above 320 nm was obtained for PAS(PMDA/DCHM). The difference in absorption spectra of PAS(PMDA/PDA) from that of PAS(PMDA/DCHM) can be related to the existence of intra- and intermolecular charge transfer (CT) for PAS(PMDA/PDA). The absorption spectra of PASs with PDA in films are red shifted compared to those of corresponding PAAs in films, while the absorption spectra of PASs in water are blue shifted compared to those of corresponding PAAs in DMF. No differences in the absorption spectra of PAAs and PASs were found in DMF/H2O (9/1) mixed solvent. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1329-1340, 1998
    Zusätzliches Material: 8 Ill.
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  • 271
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    Polyurethanes crosslinked by metals and their complexes with crown ether (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1379-1386 
    Details
    ISSN: 0887-624X
    Schlagwort(e): polyrethanes ; crown ether ; metal complexes ; X-ray scattering ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Two types of crosslinked polyurethanes (PU) have been synthesized: (a) PU crosslinked by metal ions (Cu2+ and Co2+), and (b) PU crosslinked by the complexes of metals with crown ether. Using X-ray scattering under small and wide angles the peculiarities of the structure of networks have been investigated. It was found that PU crosslinked by the metal crown ether complexes have a looser structure because of the bulky crosslink and diminished molecular mobility of the chains between two crosslinks, as was proven by the dielectric spectroscopy method. The X-ray and IR data have allowed proposing a scheme of the structure of the crosslinked PU with various types of crosslinks. The structures discovered may be considered as similar to metal catenandes. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1379-1386, 1998
    Zusätzliches Material: 4 Ill.
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  • 272
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    High α transitions of new polyamides based on diamantane (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1257-1263 
    Details
    ISSN: 0887-624X
    Schlagwort(e): polyamides ; diamantane ; synthesis ; characterization ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A series of new polyamides were synthesized by direct polycondensation of the 1,6-bis(4-aminophenyl)diamantane with various dicarboxylic acids. The soluble polyamides had high inherent viscosities, ranging from 0.73 to 1.21 dL/g. Polyamides derived from 5-tert-butylisophthalic acid and (±)-1,3-cyclohexanedicarboxylic acid were soluble in N-methyl-2-pyrrolidone (NMP) and pyridine. When NMP and N-dimethylacetamide (DMAc) were added with 3% (w/v) LiCl, the solubilities of polyamides derived from 4,4′-oxybis(benzoic acid) and cis-1,4-cyclohexanedicarboxylic acid were markedly enhanced. Polyamides had tensile strengths of up to 87.8 MPa, elongation to breakage values of up to 19.3%, and initial moduli of up to 2.1 GPa. Dynamic mechanical analysis (DMA) reveals that the polyamides have three relaxations. Their α relaxations occurred at high temperatures, ranging from 380 to 462°C. Three of polyamides exhibited good retention of storage modulus (above 108 Pa) at a temperature exceeding 410°C. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1257-1263, 1998
    Zusätzliches Material: 5 Ill.
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  • 273
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    Copolymerization of ethyl α-(hydroxymethyl)acrylate with maleimide and characterization of the resulting copolymer (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1291-1299 
    Details
    ISSN: 0887-624X
    Schlagwort(e): copolymerization ; maleimide ; ethyl α-(hydroxymethyl)acrylate ; characterization ; incomplete crystallinity ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Copolymerization of maleimide (MI) and ethyl α-(hydroxymethyl)acrylate (EHMA) was performed at 60°C with AIBN as the initiator in THF. The monomer reactivity ratios were determined as r1 (MI) = 0.13 and r2 (EHMA) = 2.20. As the molar fraction of MI in the monomer feed increased, the initial rate of copolymerization decreased. TGA diagrams suggested the crosslinking reaction of the copolymer on heating. DSC and WAXD results suggested the existence of incomplete crystallinity in the copolymer. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1291-1299, 1998
    Zusätzliches Material: 9 Ill.
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  • 274
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    Digitale Medien
    Plasma polymerization of styrene with controlled particle energy (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1265-1270 
    Details
    ISSN: 0887-624X
    Schlagwort(e): plasma polymerization ; glow discharge ; controlled particle energy ; polymer films ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A new type of reactor for plasma polymerization was developed in order to achieve an effective control of styrene polymerization process. Electrons and ions were extracted from the radio frequency (rf) glow discharge region to the downstream region to generate plasma polymerization. The energy of extracted ionized particles was controlled by the bias voltage of a screen grid unit. Deposited polymer thin films were analyzed by X-ray photoelectron spectroscopy (XPS) and infrared (IR) spectroscopy. The result showed that the polarity and energy of the extracted particles had considerable effect on the deposition rate and structure of the deposited films. At each bias polarity there was a maximum deposition rate vs. voltage magnitude, and the maximum at the positive voltage was higher. In addition, the bulk aromaticity of the film deposited at the negative bias was lower than at the positive bias; the surface aromaticity of the films was much higher than that of the films prepared by usual rf discharge. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1265-1270, 1998
    Zusätzliches Material: 6 Ill.
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  • 275
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    Digitale Medien
    Vapor phase deposition of polybenzoxazoles (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1317-1328 
    Details
    ISSN: 0887-624X
    Schlagwort(e): vapor phase deposition ; polybenzoxazoles ; poly(phenylenebenzoxazole) ; thermal depolymerization ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Vapor phase deposition was carried out on multifunctional aliphatic and aromatic benzoxazoles to yield powdered samples of poly(dimethylenebenzoxazoles). Representative aliphatic and aromatic poly(dimethylenebenzoxazoles) were also synthesized through solution methods using 4-amino-3-hydroxyhydrocinnamic acid and 2-(4-(bromomethyl)phenyl)-6-(bromomethyl)benzoxazole, respectively, as monomers. Both aromatic and aliphatic polybenzoxazoles containing —CH2CH2— units in the polymer backbone displayed catastrophic weight loss over a very narrow temperature range. This is in contrast with other polybenzoxazoles which show a gradual weight loss over 500-1000°C. Vapor phase deposition carried out under vacuum on the polymers gave similar polymers in the collection zone suggesting the catastrophic weight loss is attributed to thermal depolymerization of the polymer through a diradical intermediate similar to the thermolysis and polymerization of [2.2]paracyclophane. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1317-1328, 1998
    Zusätzliches Material: 20 Ill.
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  • 276
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    Soluble alternating copolyimides containing the tetrahydro[5]helicene unit (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1349-1353 
    Details
    ISSN: 0887-624X
    Schlagwort(e): alternating ; copolyimide ; tetrahydro[5]helicene ; [5]helicene ; solubility ; molecular modeling ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A series of novel copolyimides have been synthesized from three commercially available dianhydrides and two diamine monomers containing the tetrahydro[5]helicene unit. Some of the copolyimides were soluble in common organic solvents such as 1,1,2,2-tetrachloroethane, N,N-dimethylacetamide, and N-methyl-2-pyrrolidinone. Molecular modeling was used to explain the enhanced solubility of the presented polyimides, based on structural features of the tetrahydro[5]helicene monomeric units. The onset temperatures for 5% weight loss for these polyimides, as assessed by thermogravimetry, were above 430°C in nitrogen. Inherent viscosities of the obtained polyimides were above 0.36 dL/g. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1349-1353, 1998
    Zusätzliches Material: 2 Ill.
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  • 277
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    Stereochemical and compositional assignment of acrylonitrile/methyl methacrylate copolymers by DEPT and inverse HECTOR NMR spectroscopy (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1081-1092 
    Details
    ISSN: 0887-624X
    Schlagwort(e): NMR ; microstructure ; acrylonitrile/methyl methacrylate copolymer ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The acrylonitrile/methyl methacrylate copolymers of different monomer concentration were prepared by photo polymerization using uranyl ion as initiator. The carbon 13 and proton spectra of these copolymers are overlapping and complex. The complete spectral assignment of the 13C- and 1H-NMR spectra were done with the help of Distortionless Enhancement by Polarization Transfer (DEPT) and two dimensional 13C-1H Heteronuclear Single Quantum Correlation (HSQC) experiments. The methylene, methine and the methyl carbon resonances show both stereochemical (triad level) and compositional (dyad, triad, tetrad, pentad and hexad level) sensitivity. 2D Double Quantum Filtered Correlated Spectroscopy (DQFCOSY) experiment was used to ascertain the various geminal couplings between the methylene protons. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1081-1092, 1998
    Zusätzliches Material: 10 Ill.
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  • 278
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    Digitale Medien
    Self-propagating frontal copolymerization (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1117-1126 
    Details
    ISSN: 0887-624X
    Schlagwort(e): frontal copolymerization ; propagation velocity ; polymer chain ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The application of self-propagating frontal polymerization (FP) to synthesize copolymers has been investigated. Frontal copolymerizations of methyl methacrylate and methacrylic acid (MMA-MAA), acrylic acid and methacrylic acid (AA-MAA), and styrene and methacrylic acid (STY-MAA) with benzoyl peroxide (BPO) as initiator have been performed. The measured front velocities have been compared with the results of a suitably developed model. This is based on the pseudokinetic approach, accounts for the depropagation reaction, and is fully predictive; i.e., it does not include any adjustable parameter (although one had to be used for the specific experimental setup used in this work). An explicit, simplified solution of the model has been obtained using the constant pattern approximation. The microstructures of copolymers produced in bulk and by FP have been analyzed by differential scanning calorimetry. Their comparison indicates that self-propagating frontal copolymerization provides a substantial improvement in the uniformity of the chain composition distribution. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1117-1126, 1998
    Zusätzliches Material: 8 Ill.
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  • 279
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    Vinyl monomers bearing chromophore moieties and their polymers. V. Synthesis and fluorescence behavior of a vinyloxy monomer bearing electron-accepting chromophore moiety, N-(2-(vinyloxy)ethyl)-1,8-naphthalimide, and its polymer (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1111-1116 
    Details
    ISSN: 0887-624X
    Schlagwort(e): N-(2-(vinyloxy)ethyl)-1,8-naphthalimide ; fluorescence structural self-quenching effect ; C60 ; electron donor ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A vinyloxy monomer bearing electron-accepting chromophore, N-(2-(vinyloxy)ethyl)-1,8-naphthalimide (VOENI), was synthesized by reaction of potassium 1,8-naphthalimide with 2-chloroethyl vinyl ether. VOENI can be homopolymerized by cationic initiation and copolymerized with maleic anhydride (MAn) under radical initiation. The fluorescence behaviors of VOENI and its polymers were investigated. It has been found that the fluorescence intensity of the VOENI monomer is much lower than that of its polymers at the same chromophore concentration. This means that a “structural self-quenching effect” (SSQE) has been also observed in the vinyloxy monomer consisting of an electron-accepting chromophore, which has opposite electronic structure in comparison with acrylates bearing electron-donating chromophores as we have reported previously. The SSQE is attributed to the charge-transfer interaction between the electron-accepting chromophore and the electron-donating double bond in the same molecule. The fluorescence quenching of 1,8-naphthalic anhydride and P(VOENI-co-MAn) by ethyl vinyl ether (EVE), dihydrofuran, triethylamine (TEA), etc. evidences that the electron-rich vinyloxy group does act as an important role in the SSQE of VOENI. C60 can also quench the fluorescence of the polymers, and an upward deviation from the linearity of the Stern-Volmer plot was observed showing that C60 acted as a powerful electron donor to quench the fluorescence of the copolymer. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1111-1116, 1998
    Zusätzliches Material: 6 Ill.
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    Novel one-pot syntheses of sulfur-containing polymers from a bifunctional five-membered cyclic dithiocarbonate (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1189-1195 
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    ISSN: 0887-624X
    Schlagwort(e): one-pot syntheses ; sulfur-containing polymers ; dithiol ; bifunctional five-membered cyclic dithiocarbonates ; diisocyanates ; acid dichlorides ; dibromoalkane ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Novel one-pot syntheses of sulfur-containing polymers from a bifunctional five-membered cyclic dithiocarbonate (1a) were carried out. Polythiourethanes were obtained by the polyaddition of 4,4′-methylenebis(phenyl isocyanate), tolylene 2,6-diisocyanate, and hexamethylene diisocyanate with a dithiol (2a) obtained by the reaction of 1a and benzylamine under mild conditions. Polythioesters were also obtained by the polycondensation of terephthaloyl and succinyl chlorides with 2a. Further, polythioether was obtained by the polycondensation of α,α′-dibromo-p-xylene with 2a. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1189-1195, 1998
    Zusätzliches Material: 1 Ill.
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  • 281
    Digitale Medien
    Digitale Medien
    Poly(arylene ether)s, poly(arylene thioether)s, and poly(arylene sulfone)s derived from a dihydroxy(imidoarylene) monomer (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1201-1208 
    Details
    ISSN: 0887-624X
    Schlagwort(e): poly(arylene ether) ; poly(arylene thioether) ; poly(arylene sulfone) ; polyimide ; pendent group ; one-pot polymerization ; thiocarbamate ; thermal stability ; high-performance polymer ; oxidation ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Novel poly(arylene ether)s, poly(arylene thioether)s, and poly(arylene sulfone)s were synthesized from the dihydroxy(imidoarylene) monomer 1. The syntheses of poly(arylene ether)s were carried out in DMAc in the presence of anhydrous K2CO3 by a nucleophilic substitution reaction between the bisphenol and activated difluoro compounds. Poly(arylene thioether)s were synthesized according to the recently discovered one-pot polymerization reaction between a bis(N,N′-dimethyl-S-carbamate) and activated difluoro compounds in the presence of a mixture of Cs2CO3 and CaCO3. The bis(N,N′-dimethyl-S-carbamate) 3 was synthesized by the thermal rearrangement reaction of bis(N,N′-dimethylthiocarbamate) 2, which was synthesized from 1 by a phase-transfer catalyzed reaction. The poly(arylene thioether)s were further oxidized to form poly(arylene sulfone)s, which would be very difficult, if not impossible, to synthesize by other methods. All of the polymers described have extremely high Tgs and thermal stability as determined from DSC and TGA analysis. Poly(arylene sulfone)s have the highest Tgs and they are in the range of 298-361°C. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1201-1208, 1998
    Zusätzliches Material: 2 Ill.
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  • 282
    Digitale Medien
    Digitale Medien
    Synthesis and characterization of aromatic poly(ether ketone)s containing cyclotriphosphazene units (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1227-1232 
    Details
    ISSN: 0887-624X
    Schlagwort(e): cyclotriphosphazene ; aromatic poly(ether ketone) ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Bis(4-oxybenzoic acid) tetrakis(phenoxy) cyclotriphosphazene (IUPAC name: 4-[4-(carboxyphenoxy)-2,4,6,6-tetraphenoxy-1,3,5,2λ5,4λ5,6λ5-triazatriphosphinin-2-yl]oxy-benzoic acid) was synthesized and direct polycondensed with diphenylether or 1,4-diphenoxybenzene in Eaton's reagent at the temperature range of 80-120°C for 3 hours to give aromatic poly(ether ketone)s. Polycondensations at 120°C gave polymer of high molecular weight. Incorporation of cyclotriphosphazene groups in the aromatic poly(ether ketone) backbone greatly enhanced the solubility of these polymers in common organic polar solvents. Thermal stabilities by TGA for two polymer samples of polymer series ranged from 390 to 354°C in nitrogen at 10% weight loss and glass transition temperatures (Tg) ranged from 81.4 to 89.6°C by DSC. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1227-1232, 1998
    Zusätzliches Material: 2 Ill.
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  • 283
    Digitale Medien
    Digitale Medien
    Preparation and thermotropic liquid crystalline properties of semirigid copolyurethanes composed of biphenyl units and partially fluorinated aliphatic chains (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1243-1249 
    Details
    ISSN: 0887-624X
    Schlagwort(e): semirigid copolyurethanes ; biphenyl unit ; fluorine-containing diols ; alkylene diphenyl dicarbamates ; melt polycondensation ; nematic phase ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: New semirigid thermotropic liquid crystalline (LC) copolyurethanes 4 and 5 made up of biphenyl units and partially fluorinated aliphatic chains in the backbones were synthesized by melt polycondensation of a mixture of a dioxydihexanol of biphenyl 1 and two fluorine-containing diols 2a,b taken in definite feed mole ratios with alkylene diphenyl dicarbamates 3a-i having various lengths of aliphatic chains. The assigned structures of copolyurethanes 4 and 5 were identified by FTIR, 1H- and 13C-NMR spectra, and elemental analyses. The thermal and mesogenic properties were evaluated by differential scanning calorimetry (DSC), thermal mechanical analyses (TMA), polarizing microscopy, and temperature-changeable X-ray analyses, whose measurements indicated that the copolymers 4 and 5 form thermotropic nematic phases and have glass transition steps around room temperature. It is suggested that the incorporation of partially fluorinated aliphatic chains into the backbones has no drastic effect on the LC formation in the semirigid copolyurethanes 4 and 5. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1243-1249, 1998
    Zusätzliches Material: 4 Ill.
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  • 284
    Digitale Medien
    Digitale Medien
    Hyperbranched polymers 10 years after (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1685-1698 
    Details
    ISSN: 0887-624X
    Schlagwort(e): hyperbranched polymer ; dendrimers ; comb-burst dendrimers ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: It has been about 10 years since the first intentional preparation of hyperbranched polymer was disclosed. Hyperbranched polymers, as well as dendrimers, may find utilities in the areas where the structural uniqueness of these polymers gives merit. There has been much progress in the structural understanding and the methods of synthesis of these polymers. However, functional understanding and utility of these polymers are still in infancy. Better understanding on physical properties of these polymers, such as solubility and miscibility of these polymers in solvents or with polymers, and functional group dependency to the thermal relaxation process are needed for further development of the subject. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A: Polym. Chem. 36: 1685-1698, 1998
    Zusätzliches Material: 4 Tab.
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  • 285
    Digitale Medien
    Digitale Medien
    Copolymerization of dienes with neodymium tricarboxylate-based catalysts and cis-polymerization mechanism of dienes (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1707-1716 
    Details
    ISSN: 0887-624X
    Schlagwort(e): neodymium tricarboxylate ; cis-poly (2,3-dimethylbutadiene) ; copolymerization of dienes ; cis-1,4 polymerization mechanism ; back-biting coordination ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: It was found that poly(butadiene), poly(isoprene), and poly(2,3-dimethylbutadiene) with high cis-1,4 content were obtained with Nd(OCOR)3-(i-Bu)3Al-Et2AlCl catalysts (R = CF3, CCl3, CHCl2, CH2Cl, CH3) in hexane at 50°C [cis-1,4 content: poly(BD), 〉 98%; poly(IP), ≥ 96%; poly(DMBD), ≥ 94%]. Copolymerization of IP and styrene (St) was carried out at various monomer feed ratios to evaluate the monomer reactivity ratio and cis-1,4 content of the diene unit and then to elucidate the cis-1,4 polymerization mechanism of IP. The cis-1,4 content of the IP unit in the copolymers decreased with increasing St content in the copolymers. The cis-1,4 polymerization was disturbed by incorporating St unit in the copolymers, since the penultimate St unit hardly coordinates to the neodymium metal, resulting in a decrease of the cis-1,4 content in the copolymers. That is, the cis-1,4 polymerization of IP is suggested to be controlled by a back-biting coordination of the penultimate diene unit. On the other hand, in the case of poly(BD-co-IP) and poly(BD-co-DMBD), the cis-1,4 content of the BD, IP, and DMBD units in the copolymers was almost constant (cis: 94-98%), irrespective of the monomer feed ratios and polymerization temperature. Consequently, the penultimate IP and DMBD units favorably control the terminal BD, IP, or DMBD unit to the cis-1,4 configuration through the back-biting coordination. For the monomer reactivity ratios, a clear difference was observed in each system: rBD = 1.22, rIP = 1.14; rBD = 40.9, rDMBD = 0.15. Low polymerizability of DMBD was mainly ascribed to the steric effect of the methyl substituents. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1707-1716, 1998
    Zusätzliches Material: 6 Ill.
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  • 286
    Digitale Medien
    Digitale Medien
    Microstructure effect in the coupling reactions of polymeric organolithium compounds using chlorosilanes (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1743-1753 
    Details
    ISSN: 0887-624X
    Schlagwort(e): coupling reaction ; living polymer ; microstructure ; coupling yield ; 1,4-enchainment ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The most important variable affecting the yield in the coupling reactions of polymeric organolithium compounds with chlorosilane compounds has been investigated through size-exclusion chromatographic (SEC) analysis. The coupling reaction of poly(styryl)lithium with dichlorodimethylsilane as a silane-coupling agent provided 44 wt % of the coupling yield. The coupling yield, depending on the chain end reactivity of active polymers, was not greatly affected. The addition of a Lewis base such as N,N,N′,N′-tetramethylethylenediamine (TMEDA) even after complete polymerization of the dienes in hydrocarbon seems to affect the coupling reaction, resulting in decreasing the yield. The 1,2- or 3,4-enchain contents in the polydiene backbones affected the reduction of the linking efficiency in the coupling of the poly(dienyl)lithiums with chlorosilanes as the linking agent. The linking yields of the active polymers including over 75 mol % of 1,2- or 3,4-enchainment on the polydiene segment were below 20 wt %. The linking yields exhibited a dependence not only on the steric requirement of the chain end, but also the microstructure of the polydiene segment. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1743-1753, 1998
    Zusätzliches Material: 5 Ill.
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  • 287
    Digitale Medien
    Digitale Medien
    Synthesis and properties of novel polymers having S-methyldibenzothiophenium salt moieties (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1779-1784 
    Details
    ISSN: 0887-624X
    Schlagwort(e): poly(sulfonium salt) ; poly(2-vinyldibenzothiophene) ; 5-methyl-2-vinyldibenzothiophenium tetrafluoroborate ; sulfonium monomer ; radical polymerization ; polymer reaction ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A polymer having dibenzothiophenium salt moieties [poly(sulfonium salt), 2] was prepared by the reaction of poly(2-vinyldibenzothiophene) (1) with CH3I and AgBF4 in CH2ClCH2Cl at room temperature for 24 h. The obtained polymer 2 was found to contain 71% of the methyldibenzothiophenium tetrafluoroborate unit. A monomer carrying the sulfonium salt moiety, i.e., 5-methyl-2-vinyldibenzothiophenium tetrafluoroborate (4), was independently prepared and subjected to radical polymerization to give a polymer (5) in 88% yield (methyldibenzothiophenium tetrafluoroborate unit: 79%). The thermal decompositions of 2 and 5 took place in two steps; the first step involved the formation of polymer 1 by demethylation. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1779-1784, 1998
    Zusätzliches Material: 3 Ill.
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  • 288
    Digitale Medien
    Digitale Medien
    Synthesis and characterization of novel thermotropic liquid crystalline copoly(ester imide)s (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1791-1803 
    Details
    ISSN: 0887-624X
    Schlagwort(e): liquid crystalline polymers ; copoly(ester imide)s ; smectic ; nematic ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Novel liquid crystalline copoly(ester imide)s were synthesized via polyesterification of triethyleneglycol bis(4-carboxyphenyl) ether (1e), diacetoxybiphenyl, and diacids with imide moieties. The effects of composition on the changes of Tg, Tm, and Ti were examined by global TSC and DSC. Thermal gravimetric analyses (TGA) found that 4a-d and 5a-g possess higher thermal stability. Strong stir opalescence phenomenon and observations from polarized optical microscopy identified that 2b-e and 3a-d possess the typical schlieren texture of an enantiotropic nematic mesophase. The birefrigent melts of 4a-d and 5a-g, however, displayed particular liquid crystalline behavior. Copolymers with higher aromatic imide ring content (4a-d, 5a-g) form a layered structure and an enantiotropic smectic mesophase in the melting state. The melt viscosity of the semetic mesophase was higher than the nematic mesophase which was observed by capillary rheometer. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1791-1803, 1998
    Zusätzliches Material: 19 Ill.
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  • 289
    Digitale Medien
    Digitale Medien
    Synthesis and binding properties of a noncovalent molecularly imprinted testosterone-specific polymer (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1725-1732 
    Details
    ISSN: 0887-624X
    Schlagwort(e): crosslinked polymer ; template polymerization ; noncovalent molecular imprinting ; testosterone ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: In this study, molecular imprinting was used to develop a method based on noncovalent interactions for synthesis of a testosterone-specific polymer. The effect of the different template-monomer ratios, the particle sizes of polymers, and chromatographic mobile phases on steroid-polymer interactions are discussed. The polymer obtained was found to interact specifically with testosterone, while other steroids under study were eluted close to the void volume in the HPLC experiments. Batch rebinding studies in acetonitrile were undertaken to quantitatively evaluate the affinity of the polymer for testosterone. During this experiment, the testosterone concentration was measured in two ways: spectrophotometrically and by HPLC on a column with testosterone-specific imprinted polymer synthesized by us. Both methods resulted in similar values of association constants and the number of binding sites. However, the second method has obvious advantages when the analyzed solution contains a mixture of optically dense compounds. The results obtained focus on the two-point binding nature of the imprinted polymer-testosterone interaction and the significant role of hydrogen bonds between the OH group of testosterone and carboxy group of methacrylic acid residues inside specific recognition sites of the imprinted polymer. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1725-1732, 1998
    Zusätzliches Material: 5 Ill.
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  • 290
    Digitale Medien
    Digitale Medien
    The use of tetraalkylphosphonium-tetrafluoroborate-tetrafluoroboric acid in the curing of a liquid crystalline epoxy resin (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1457-1471 
    Details
    ISSN: 0887-624X
    Schlagwort(e): epoxy ; catalyst ; liquid crystalline ; kinetic ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Tetraalkylphosphonium-Tetrafluoroborate-Tetrafluoroboric Acid was used as a catalyst in the curing of a liquid crystalline epoxy. Under some conditions the Tetraalkylphosphonium-Tetrafluoroborate-Tetrafluoroboric Acid actually retarded the reaction. An extensive experimental and kinetic analysis is presented anda mechanism for the reaction retardation is proposed. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1457-1471, 1998
    Zusätzliches Material: 16 Ill.
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  • 291
    Digitale Medien
    Digitale Medien
    New sulfonated engineering polymers via the metalation route. II. Sulfinated/sulfonated poly(ether sulfone) PSU Udel and its crosslinking (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1441-1448 
    Details
    ISSN: 0887-624X
    Schlagwort(e): sulfinated/sulfonated poly(ether sulfone) ; partial oxidation ; crosslinked membranes ; S-alkylation of sulfinate ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: New mixed sulfinated/sulfonated polysulfone PSU Udel has been produced by partial oxidation of sulfinated PSU with NaOCl. From the mixed sulfinated/sulfonated PSU, thin crosslinked polymer films have been produced by S-alkylation of the residual sulfinate groups with α,ω-diiodoalkanes having 4-10 —(CH2)— units. The advantages of the partial oxidation process using NaOCl are as follows: (1) The desired oxidation degree can be adjusted finely. (2) No side reactions take place during oxidation. (3) The partially oxidized polymers is stable at ambient temperature. By variation of the oxidation degree of the sulfinated/sulfonated prepolymer and by variation of the chain length of the diiodo crosslinker, crosslinked membranes with a large range of properties in terms of ionic conductivity, swelling, and permselectivity have been produced. The partially oxidized polymers have been characterized by redox titration, 1H-NMR, and FTIR. The crosslinked membranes have been characterized in terms of ionic conductivity (resistance), permselectivity, and swelling in dependence on ion-exchange capacity and oxidation degree of the prepolymers. In addition, the thermal stabilities of the membranes have been determined by TGA, and FTIR spectra have been recorded on the crosslinked films. Selected membranes show low ionic resistances, low swelling, and good temperature stability which makes them promising candidates for application in (electro)membrane processes. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1441-1448, 1998
    Zusätzliches Material: 10 Ill.
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  • 292
    Digitale Medien
    Digitale Medien
    Polymerization of N,N′-methylenebis(acrylamide) using potassium peroxydiphosphate-thiocarboxylic acid redox systems: A comparison (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 11-20 
    Details
    ISSN: 0887-624X
    Schlagwort(e): polymerization ; divinyl monomer ; redox ; thiocarboxylic acid ; mechanism ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The kinetics of aqueous polymerization of the symmetrical nonconjugated divinyl monomer N,N′-methylenebis(acrylamide) (MBA), was studied at 35°C and at constant ionic strength under nitrogen atmosphere involving potassium peroxydiphosphate (PDP) as oxidant with three different activators thiolactic acid (TLA), thiomalic acid (TMA), and thioglycollic acid (TGA). The rate of polymerization, RP, and rate of disappearance of peroxydiphosphate, -RPDP have been followed while polymerization was initiated separately by the PDP-TLA/PDP-TMA/PDP-TGA redox systems. RP for the above three systems showed first-order dependences on both [monomer] and [activator] and zero-order dependence on [PDP]. First-order dependence on [PDP] and zero-order dependences on [monomer] and [activators] were observed with respect to -RPDP in the above three systems. A reaction mechanism which involves complex formation between PDP and thiocarboxylic acid, propagation through intramolecular-intermolecular reactions, degradative chain transfer reaction of the growing radical with PDP, and linear termination by the interaction of the chain radical with primary radical was proposed. The kinetic parameters for the three polymerization systems were calculated and compared. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 11-20, 1998
    Zusätzliches Material: 4 Ill.
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  • 293
    Digitale Medien
    Digitale Medien
    High-pressure synthesis and properties of aliphatic-aromatic polyimides via nylon-salt-type monomers derived from aliphatic diamines and benzophenonetetracarboxylic acid (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 39-47 
    Details
    ISSN: 0887-624X
    Schlagwort(e): aliphatic polyimides ; polycondensation ; salt monomers ; crystallinity ; thermal behavior ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Aliphatic polyimides (P-XBTA) having inherent viscosities of 0.4-1.4 dL/g were readily synthesized by the high-pressure polycondensation of the salt monomers, composed of aliphatic diamines having various methylene chain lengths (X = 4-12) and 3,3′,4,4′-benzophenonetetracarboxylic acid (BTA), under 200-250 MPa at 200-320°C. The salt monomers with odd-numbered methylene units were found to be more susceptible to crosslinking than those containing even-numbered methylene chains. The polyimides having even-numbered methylene units were highly crystalline, whereas those with odd-numbered methylene chains were crosslinked and therefore amorphous with only one exception, i.e., P-11BTA. The thermal behavior of these polymers was also studied. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 39-47, 1998
    Zusätzliches Material: 6 Ill.
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  • 294
    Digitale Medien
    Digitale Medien
    Preparation and properties of anion exchange membranes having pyridinium or pyridinium derivatives as anion exchange groups (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 49-58 
    Details
    ISSN: 0887-624X
    Schlagwort(e): anion exchange membrane ; electrodialysis ; permselectivity between two anions ; pyridinium groups ; hydrophilicity of anion exchange membrane ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Anion exchange membranes with pyridinum groups and various pyridinium derivative groups were prepared from a copolymer membrane composed of chloromethylstyrene and divinylbenzene, and pyridine and pyridine derivatives. The anion exchange membranes obtained showed excellent electrochemical properties in electrodialysis. The transport numbers of sulfate ions, bromide ions, nitrate ions, and fluoride ions relative to chloride ions were evaluated in connection with the species of a substituent and the position of the substituent in the pyridinium groups. In general, when a hydrophilic substituent (methanol groups) existed at the 2-position of the pyridinium groups, nitrate ions and bromide ions, which are less hydrated, permeated through the membranes with difficulty, and sulfate ions permeated selectively through the membranes. On the other hand, when hydrophobic groups, for example, ethyl groups, existed at the 2-position of the pyridinium groups, bromide ions and nitrate ionspermeated selectively through the membranes and fluoride ions had difficulty permeating through the membranes. The carbon number of the alkyl chain of 4-alkyl pyridinium groups also affected permeation of nitrate ions and bromide ions due to the change in hydrophilicity of the membranes. Though the hydration of the anions and the species of the substituent at the 2-position of the pyridinium groups were related to selective permeation of the anion through the membranes, permeation of sulfate ions was not as sensitive to the hydrophilicity of the membranes. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 49-58, 1998
    Zusätzliches Material: 11 Ill.
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  • 295
    Digitale Medien
    Digitale Medien
    A polyimide precursor solution based on a novel concept (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1961-1964 
    Details
    ISSN: 0887-624X
    Schlagwort(e): Poly(4,4′-phenylene-3,3′,4,4′-biphenyltetracarboxyimide) ; poly(4,4′-oxydiphenylenepyromellitimide) ; precursor solution ; aprotic polar solvent ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: No abstract.
    Zusätzliches Material: 4 Ill.
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  • 296
    Digitale Medien
    Digitale Medien
    Hydrosilation routes to materials with high thermal and oxidative stabilities (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1969-1972 
    Details
    ISSN: 0887-624X
    Schlagwort(e): hydrosilation ; polymer ; siloxane ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: No abstract.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 297
    Digitale Medien
    Digitale Medien
    Covalent modification in aqueous solution of poly-γ-D-glutamic acid from bacillus licheniformis (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1995-1999 
    Details
    ISSN: 0887-624X
    Schlagwort(e): poly-γ-D-glutamic acid ; biopolymer ; covalent modification ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Methods for the covalent modification in aqueous solution of poly-γ-D-glutamic acid from Bacillus licheniformis have been studied. Co-derivatization of a synthetic UV-absorbent amine and ethanolamine, using a water-soluble carbodi-imide coupling agent, yielded a water-soluble modified polymer. Derivatization of the polymer was accompanied by cleavage of the γ-linked polypeptide backbone, and a reduction in molecular mass from 170 to 10 kDa. A procedure was developed for the removal of noncovalently bound ligands by treatment with 5 M CaCl2. The polymer sidechains also reacted in aqueous solution with p-nitrophenyl acetate to form covalent linkages. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 1995-1999, 1998
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 298
    Digitale Medien
    Digitale Medien
    Synthesis and radical ring-opening polymerization of vinylcyclopropanes bearing vinylsilane groups (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2037-2042 
    Details
    ISSN: 0887-624X
    Schlagwort(e): radical polymerization ; vinylcyclopropane ; vinylsilane ; desilylation ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Synthesis and radical polymerization of novel vinylcyclopropanes; 1-carboethoxy-2-trimethylsilyl-2-vinylcyclopropane (1a) and 1-carboethoxy-2-(1-trimethylsilyl)-vinylcyclopropane (1b), were examined. 1a and 1b were prepared by the coupling reaction of 2-trimethylsilylbutadiene with ethyl diazoacetate, which was prepared from glycine ethyl ester hydrochloride. The radical polymerization of 1a and 1b was carried out at 60°C in bulk for 40 h in the presence of 2,2′-azobis(isobutyronitrile) (5 mol % vs. monomer). Poly(1) consisted of a 1,5-ring-opened unit. Desilylation reaction of poly(1) proceeded quantitatively in aqueous hydrochloric acid. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2037-2042, 1998
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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    Artikel (Nationallizenzen)
  • 299
    Digitale Medien
    Digitale Medien
    Synthesis and properties of stereoregular poly(ester amides) derived from carbohydrates (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 67-77 
    Details
    ISSN: 0887-624X
    Schlagwort(e): stereoregular poly(ester amides) ; carbohydrate-based polymers ; polycondensation reactions ; chiral polymers ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Two poly(ester amides) containing three methoxy groups stereoregularly attached to the main chain have been prepared by using naturally occurring L-arabinose and D-xylose as the starting materials. The polymers were prepared by the active ester polycondensation method and characterized by elemental analysis, IR, and 1H- and 13C-NMR spectroscopies. Both viscosimetry and GPC were used to estimate the molecular weights. The polymers are hydrophilic, one of them being water soluble, and exhibited moderate optical activity. Thermal and X-ray diffraction studies revealed that they are slightly crystalline and stable up to 250°C under nitrogen. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 67-77, 1998
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 300
    Digitale Medien
    Digitale Medien
    Properties and morphology of poly(L-lactide). II. Hydrolysis in alkaline solution (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 59-66 
    Details
    ISSN: 0887-624X
    Schlagwort(e): poly(lactide) ; hydrolysis ; degradation ; erosion ; alkaline solution ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Hydrolysis of poly(L-lactide) (PLLA) films in 0.01N NaOH at 37°C was investigated by gel permeation chromatography, differential scanning calorimetry, scanning electron microscopy, and polarizing optical microscopy. The change in molecular weight distribution and surface morphology of PLLA films during hydrolysis revealed that PLLA film hydrolysis in dilute alkaline solution proceeded mainly via the surface erosion mechanism. An insignificant dependence of the rate of weight loss per unit surface area on the PLLA film thickness also supported this conclusion. Etching of the outside of PLLA spherulites resulted in preferred hydrolysis of PLLA chains in the amorphous region. The disorientation of lamella and inhomogeneous erosion in the spherulites implied that hydrolysis of PLLA chains occurred predominantly in the amorphous region between the crystalline regions in the spherulites. The rate of weight loss per unit surface area decreased linearly with the increase in the initial crystallinity of PLLA film, while the radius of spherulites had practically no significant effect on the hydrolysis of PLLA film. The specific low molecular weight of PLLA chains produced by hydrolysis increased with the rise in annealing temperature of the PLLA film, suggesting that the PLLA chains released were the component of one fold in the crystalline region. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 59-66, 1998
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
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