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  • 1985-1989  (8,271)
  • 1987  (8,271)
  • Chemistry  (8,271)
  • Organic Chemistry  (684)
  • 101
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 1755-1767 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The grafting of methyl methacrylate (MMA) onto polybutadiene (PB) latexes prepared by seeded emulsion polymerization at 50°C was investigated as a function of: (a) initiator concentration used in the secondary polymerization, (b) monomer-to-polymer ratio, (c) the specific surface area of the seed latex, and (d) the degree of conversion. The thin layer chromatography/flame ionization detection (TLC/FID) technique was used to determine the proportion of graft copolymer in the core/shell latex, It was found that grafting PMMA onto PB depended upon the concentration of initiator, decreasing as the concentration was increased. The amount of grafting increased with increasing specific surface area of the seed latex, while the molecular weight of the acetone-soluble graft copolymer decreased. The amount of graft copolymer was found to decrease concurrently with increasing monomer-to-polymer ratio and degree of conversion. These results suggest a hydrogen abstraction mechanism in the formation of graft PB-PMMA through a chain transfer process.
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  • 102
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    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 1825-1846 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The thermal degradation behavior of polyacrylamide and poly(acrylamide-co-acrylate) was studied by differential scanning calorimetry, thermogravimetric analysis, gas chromatography/mass spectrometry, and carbon-13 solid state nuclear magnetic resonance. The degradation products over the temperature range of 115-450°C were characterized. Mechanisms are proposed for the degradation processes involved.
    Additional Material: 18 Ill.
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  • 103
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    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 1887-1907 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The NMR spectra and UV absorptions of polynucleotide analogs with a poly(ethylenimine) (PEI) backbone containing adenine, cytosine, and hypoxanthine pendants have been examined. As has been shown in single-stranded polynucleotides, these polymers also exhibited base stacking behavior in aqueous solution as well as in 2,2,2-trifluoroethanol. Such stacking resulted in significant UV hypochromicities and observed differences in the NMR spectra compared to the corresponding model compounds. From continuous variation mixing experiments, well-defined base pairing interactions were observed between complementary graft polymers in aqueous solutions. Enhanced UV hypochromicity due to such interactions was also observed.
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  • 104
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    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 1967-1978 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Dimethyl phosphonomethylheptamethylcyclotetrasiloxane (II) and 1, 3-bis(dimethyl phosphonomethyl)tetramethyldisiloxane (III) have been prepared by Arbuzov reaction of trimethyl phosphite with bromomethylheptamethylcyclotetrasiloxane (I) and 1, 3-bis(bromomethyl)tetramethyldisiloxane, respectively. Dimethyl phosphonomethylmethylsiloxane dimethylsiloxane copolymers have been prepared by acid-catalyzed ring-opening polymerization of II with hexamethyldisiloxane (MM) as an end-capping reagent and by reaction of II with III as an end-capping reagent. Dimethylsiloxane polymers with dimethyl phosphonomethyldimethylsiloxy end groups have been prepared by acid-catalyzed polymerization of octamethylcyclotetrasiloxane (D4) and III. Under these conditions hydrolysis of the dimethyl phosphonate ester groups was a problem. On the other hand Arbuzov reaction of trimethyl phosphite with bromomethylmethylsiloxane dimethylsiloxane copolymer gave a dimethyl phosphonomethylmethylsiloxane dimethylsiloxane copolymer with uniform properties. These polymers have been characterized by 1H-, 13C-, 29Si-, and 31P-NMR spectroscopy. Their molecular weight distributions have been determined by gel permeation chromatography (GPC) and their thermal stability measured by TGA.
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  • 105
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    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 1979-1988 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The cationic ring-opening polymerization of trioxane and 1,3-dioxolane was found to be initiated by CO+CIO4- groups on a carbon black surface, which were introduced by the reaction of COCI groups with AgCIO4. The activation energy of the ring-opening polymerization of trioxane was estimated to be 15.5 kcal/mol. In the polymerization system, poly(oxymethylene) and poly(1,3-dioxolane) formed were effectively grafted onto carbon black depending upon the propagation of these polymers from the carbon black surface; for instance, the grafting ratio of poly(oxymethylene) onto carbon black increased with an increase in conversion and went up to about 180%. Although the grafted chain of poly(oxymethylene) was subject to stepwise thermal depolymerization from the chain ends, the thermal stability of poly(oxymethylene)-grafted carbon black was improved by acetylation of hemiformal end groups. The molecular weight of ungrafted poly(oxymethylene) formed in the polymerization was determined to be 1.8-2.0 × 104. Furthermore, the copolymerization of trioxane with 1,3-dioxolane, styrene, and other comonomers initiated by CO+CIO4- groups and the thermal stability of these acetal copolymer-grafted carbon black were investigated.
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  • 106
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    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 1463-1474 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Novel poly-Schiff bases (PSB's) that contain trans-1,2-bis(9-carbazolyl)cyclobutane(DCZB) units were synthesized by the direct polycondensation of trans-1,2-bis(3-formyl-9-carbazolyl)cyclobutane with aromatic diamines in n-amyl alcohol at 160°C. Complexation of these PSB's and of poly(vinyl DCZB) (PVDCZB) with iodine produced cation-radical salts which resulted form the transfer of an electron from DCZB moieties to iodine. All the undoped polymers were insulators having electrical conductivity of the order of 10-10-10-12 S cm-1 depending on the structure of polymers. By doping with iodine, the electrical conductivity increased by several orders of magnitude and reached a value of 10-3 S cm-1 in the case of PVDCZB and 10-5-10-6 S cm-1 in the case of PSB's. The electrical conductivity of doped PSB's increased with decreasing diamine length. PVDCZB having the same iodine content per carbazole unit as poly(9-vinyl-carbazole) (PVK) has a greater electrical conductivity than PVK.
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  • 107
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    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 1523-1543 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Preparation of new model polymers of polynucleotides with poly(vinylamine-vinylalcohol) [P(Vam-Val)] backbones and different kinds of nucleic acid base derivatives as grafted pendants is described. At first, the grafting of (-) and (±)-2-(thymin-1-yl)propionic acid [(-) and (±)TPA] onto linear P(Vam-Val) at the amino group via an amide bond was carried out in a mixed solvent of ethanol-dimethylformamide by selective N-acylation of the active ester of N-hydroxy-5-norbornene-2,3-dicarboximide (HONB) or N-hydroxysuccinimide (HOSu). This procedure gave the corresponding hydroxyl polymers P[Vam(-)T-Val] and P[Vam(±)T-Val]. In addition, direct, low temperature esterification was used to graft (-), (±)TPA, and (±)-2-(uracil-1-yl)propionic acid, [(±)UPA], onto the hydroxyl polymer at the hydroxyl group via an ester bond. This process gave the corresponding copoly(Vam-Val) with different or the same kinds of nucleic acid base derivatives. P[Vam(-)-Ve(-)T], P[Vam(±)T-Ve(±)T], P[Vam(-)T-Ve(±)U], and P[Vam(±)T-Ve(±)U] are representative examples. The related monomer and segmental model compounds were also prepared by this method; 3-aminopentane, 3-pentanol, 3-amino-1-propanol, and threo-2-amino-4-pentanol were employed in the syntheses. The segment models were separated and purified using HPLC techniques.
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  • 108
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    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 2231-2240 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The complexes formed between palladium (II) and a polymeric ligand derived from L-asparagine, poly(N-methacryloyl-L-asparagine) (PNMAsn) have been investigated by electronic absorption and circular dichroism. N-isobutyroyl-L-asparagine (NIBAsn) was also synthesized and studied with the purpose of comparison with its polymeric analog. NIBAsn gives two complexes: at low pH, an optically active complex between one carboxylate and one secondary amide nitrogen (so-called 1N complex), and at higher pH, a 2N complex involving the primary and secondary amide group. This complex is also optically active. PNMAsn gives at low pH a 1N complex similar to that of NIBAsn, but at higher pH the 2N complex is formed between two carboxylate groups and two secondary amide groups of two different side chains of the polymer. At very high pH this 2N complex is hydrolyzed, i.e., the carboxylate-palladium bonds are replaced by hydroxyle-palladium bonds, and the complex becomes optically inactive.
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  • 109
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    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 2261-2268 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Poly(ethylene glycol methyl ether)-b-poly(ethylenimine hydrochloride) was characterized using potentiometric and viscosimetric titration methods. The average chemical compositions of the polyamine hydrochloride salts estimated by the acid-base titration,1H-NMR, and elemental analysis were compared. The apparent dissociation constant, pK, and the inherent viscosity of the polyamine hydrochloride were found to be highly dependent on the degree of neutralization. Very strong coulombic interactions among the charged sites were observed at low pH's for this polymer.
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  • 110
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    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 2185-2193 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: N-phenylated aromatic polyureas were synthesized by the polyaddition of dianilino compounds to aromatic diisocyanates in sym-tetrachloroethane at around 100°C. Factors that influence the reaction, such as monomer concentration, reaction solvent, catalyst, temperature, and time, were studied to optimize the conditions for the preparation of high molecular weight polymers. Compared with the analogous unsubstituted aromatic polyureas, the N-phenylated polyureas were almost amorphous and soluble in a variety of solvents and had low glass transition temperatures. Some of the polymers could be cast into transparent flexible films from chloroform solutions.
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  • 111
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    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 2323-2326 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
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  • 112
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    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 2335-2341 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Poly(p-benzoquinono)diimidazoles have been synthesized under mild conditions (100 or 150°C) by one-stage polycondensation in N,N-dimethylacetamide (DMAc) or in polyphosphoric acid of 2,3,5,6-tetraamino-p-benzoquinone (TABQ) with terephthalaldehyde and isophthalaldehyde. The model compound 2,6-diphenyl-1,5-dihydro-1′,4′-benzoquinono[2′,3′-d:5′,6′-d′]diimidazole was also prepared by condensation of TABQ with benzaldehyde in DMAc at 100°C. The prepared polymers were completely insoluble in organic solvents but slightly soluble (0.5%) in strong acids with viscosities (ηinh) in the range of 0.17-0.38 dL/g (c = 0.2% in formic acid). Their thermal stability was studied by TG analysis.
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  • 113
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    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 1737-1744 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The products in inductively coupled plasma excited in organosilicic compounds were studied on chemical structures by spectroscopic methods. Plasma-polymerized tetramethylsilane (PA) contains not only Si—CH3 groups but also Si—H groups on IR and 29Si-NMR analyses. 13C-NMR spectrum of PA reveals that the crosslinked structure of PA is mainly constructed of Ch2 and CH groups. Plasma-polymerized octamethyleyclotetrasiloxane (PD4) is composed of Si—CH3 and Si—O groups. 13C- and 29Si-NMR spectra of PD4 point out the highly preservation of the structural units similar to the monomer. These data of PD4 suggest that PD4 is formed from the ring-opening polymerization by cleavages of Si—O bonds. 13C-NMR spectrum of poly[methyltrimethoxysilane] (PT) indicates the existence of CH3—O groups, meanwhile its 29Si-NMR analysis concludes that PT is chiefly composed of the structural units similar to the monomer. The surface analyses by XPS of PA, PD4 and PT suggest that these organosilicic plasma polymers resemble their starting materials.
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  • 114
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    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 1769-1779 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The polymerization of N-vinylcarbazole (NVC) in the presence of transition metal salts such as WCI6, MoCI5, TaCl5 and NbCl5 under different reaction conditions was studied. In general, aromatic solvents were found to be superior to aliphatic solvents in the polymerization of NVC, i. e., both conversion and molecular weight were higher in aromatic solvents. It was observed that the polymerization reaction proceeds rapidly and almost quantitatively, even at low monomer concentration (〈 5 × 10-2M) and at low catalyst to monomer mole ratio (10-5) in aromatic solvents. The copolymerization of NVC with acenaphthylene (ACN) was also investigated in solution at room temperature. The resulting homo- and copolymer were characterized by IR, NMR, x-ray diffraction, and elemental analysis. Thermal and photophysical properties are also reported. From the spectral data, the polymerization solvent was found to have a strong influence upon the polymer stereoregularity.
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  • 115
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    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 1793-1801 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of two novel polyamide ligands 3 and 4, containing 2,17-diaza[3.3](6,6′)-2,2′-bipyridinophane or 6,6′-bis(2-picolylaminomethyl)-2,2′-bipyridine units as part of the polymer backbone, respectively, and of the appropriate diamide model compounds 1c and 2c is described. 1H-NMR and IR spectral data support the ligand structures; furthermore, 1H-VTNMR analysis on macrocyclic diamide 1c indicates a restricted rotation of the amide bonds at ambient temperature and suggests for this molecule a fixed syn conformation in solution, with a “face to face” arrangement of the dipyridinyl moieties. Model compound 2c and polyamide 4 form stable 1:1 complexes with transition metals Co(II), Ni(II), and Cu(II). Conversely, macrocyclic model 1c and polyamide 3 exhibit the unique property to specifically complex Cu(II), even in the presence of sizeable amounts of Co(II) and Ni(II). The IR spectral changes related to the ligands upon complexation are briefly discussed.
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  • 116
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    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 1811-1823 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The polymers which have different sized crown ethers as alkali cation binding sites and photodimerizable cinnamoyl units were prepared by the cationic copolymerization of corresponding monomers. The crown-cation complexation ratio (1:1 or 2:1) was investigated by measuring quantum yields φ of the photodimerization of the crown-connected cinnamoyl units in the presence of alkali metal chlorides and also by measuring the shift of λmax of alkali metal picrates in THF on addition of the crown polymers. A significant 1:2 complex formation of alkali cations with two different sized crown ether units in the side chain of the polymers was confirmed. The alkali metal cation binding ability and selectivity of the polymers, which were studied by a method of picrate salts extraction, were markedly different from those expected from the combination of polymers of same ring-size crown ether units. When irradiated with ultraviolet (UV) light, the cinnamic acid ester groups of the polymers caused dimerization even in dilute solutions. The cation binding ability of the polymers was largely enhanced by the photodimerization of the cinnamoyl moieties with suitable template cations.
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  • 117
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    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 2543-2559 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Urethane reactions of phenyl isocyanate alcohol systems with toluene as solvent and various aprotic polar solvents (including tertiary amines) as additives were carried out at constant temperature of 10-40°C. Analysis of the variation of the second order rate constants of these systems and those available in the literature indicates that formation of the hydrogen bonding complexes (alcohol with phenyl isocyanate and with aprotic solvent) and electron donor number (DN) of the aprotic solvent are the two factors allowing satisfactory explanation of the catalysis and inhibition effects of the wide range of aprotic solvents (including amines, amides, etc.). Based on these considerations, an ion-pair mechanism and the resulting kinetic equation for the urethane reaction are proposed. Verification on the kinetic equation with experimental results for the systems of phenyl isocyanate with alcohol in toluene (for the self catalysis of the alcohol), with dimethyl formamide and dimethyl sulfoxide in toluene (for the catalysis of the aprotic solvents), and with triethylamine in toluene (for the catalysis of the tertiary amines) shows satisfactory. In the mechanism, the aprotic solvent is considered to solvate the complex of phenyl isocyanate/alcohol at the active hydrogen to form an ion-pair which can undergo the urethane reaction more easily.
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  • 118
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    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 2569-2576 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An aromatic, diether-linked phthalonitrile resin, prepared from 4,4′-bis(3,4-dicyanophenoxy)biphenyl, can be converted into an environmentally stable, highly conductive material by thermal means. The conductivity of the pyrolyzed polymer can be varied and controlled as a function of both the pyrolytic temperature and annealing time. This allows the generation of a range of electrical behavior from an insulator to semiconductor and approaching metallic regions.
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  • 119
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The influence of molecular weight on thermal transitions and on their thermodynamic parameters is discussed for a random thermotropic liquid crystalline copolyether based on the reaction of a 1:1 molar mixture of 1,5-dibromopentane and 1,7-dibromoheptane with 4,4′-dihydroxy-α-methylstilbene. Optimum phase transfer catalyzed polyetherification reaction conditions were established for the synthesis of polymers containing bromoalkane chain ends only over a wide variety of molecular weights. All these copolyethers present a crystalline and an enantiotropic nematic mesophase over the entire range of molecular weights studied. Both the thermal transitions and their thermodynamic parameters are strongly molecular weight-dependent up to Mn = 10,000-12,000, after which they remain constant. The enthalpies and entropies of isotropization of the copolyethers are higher than those of melting. This is in contrast to the same thermodynamic parameters of the corresponding homopolyethers. The enthalpies and entropies of isotropization of both homopolymers and copolymers present similar values, suggesting that copolymerization does decrease the degree of order in the crystalline phase but does not significantly change the alignment degree of the mesogenic units in the nematic mesophase.
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  • 120
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    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 2021-2024 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
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  • 121
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    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 2699-2709 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The polymerization behavior of N-(p-aminobenzoyl)caprolactam was studied. It was found that polymerization could proceed by either elimination of caprolactam or by ring opening. Polymers prepared at temperatures above 200°C showed a greater tendency for ring opening to produce alternating aromatic/aliphatic copolymers than did polymers prepared at lower temperatures. Block copolymers of poly(p-benzamide) and nylon 6 were prepared by a two-stage hydrolytic polymerization process or by anionic polymerization at temperatures 〉 200°C. Polymer microstructures were determined using 13C-NMR spectroscopy by comparison with homopolymers and model alternating copolymers. The alternating copolymer prepared by condensation of N-(p-aminobenzoyl)-6-caproic acid showed a melting transition at 300-305°C in the DSC and a Tg in subsequent heating cycles of 116-119°C. Copolymers made with the two-stage process were rich in p-benzamide sequences and showed no Tg or Tm below 400°C. Copolymer made with NaH was rich in nylon 6 units, showed a Tm of 175-180°C and a Tg of 80-81°C, and was homogeneous in both the melt and solid.
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  • 122
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    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 2747-2753 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Fluorine-containing polyarylates having inherent viscosities of 0.2-0.8 dL/g were prepared from tetrafluoroisophthaloyl chloride and various bisphenols by low temperature solution polycondensation in chloroform with triethylamine or by two-phase polycondensation in a dichloromethane-water or nitrobenzene-water system with benzyltriethylammonium chloride as the phase transfer catalyst. These polyarylates were amorphous and were readily soluble in various solvents, including chloroform and N-methyl-2-pyrrolidone. The glass transition temperature of the polymer derived from 2,2-bis(4-hydroxyphenyl) propane was 150°C. These polyarylates started to lose weight around 350°C in an air or nitrogen atmosphere.
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  • 123
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    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 2791-2798 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: To investigate the polymerization systems driven by aromatization energy, 4-allylidene-2,6-dimethyl-2,5-cyclohexadien-1-one (Ia), 5,7-dimethyl-1-vinylspiro[2,5]octa-4,7-dien-6-one (Ib), 4,7-dimethyl-1-vinylspiro[2,5]octa-4,7-dien-6-one [Ic], 2-vinyl-2′-methylspiro[cyclopropane-1,4′-(1′-naphthalenone)] (Id), and 2-phenyl-2′-methylspiro[cyclopropane-1,4′-(1′-naphthalenone)] (Ie) were prepared and polymerized with sodium cyanide in N,N-dimethylformamide. Monomer Ia was highly polymerizable even at -65°C. Monomers Ib-Ie also polymerized well, giving powdery polymers that were soluble in common solvents. All the polymerizations took place through the aromatization of the cyclohexadienone ring, suggesting that the aromatization energy is the driving force for the polymerization of these monomers.
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    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 2827-2838 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: p-Vinylphenyl glycidyl ether (VPGE), a styrene derivative with an epoxy pendant, was polymerized by various cationic initiators, and its selective vinyl polymerization was investigated at low temperatures below -15°C. BF3OEt2 (a metal halide) and CF3SO3H (a strong protonic acid) polymerized both vinyl and epoxy groups of VPGE, and produced cross-linked insoluble polymers. The HI/I2 initiating system and iodine, in contrast, polymerized its vinyl group in polar solvents (CH2Cl2 and nitroethane) highly selectively in the temperature range of -15 to -40°C to give soluble polymers with a polystyrene backbone and epoxy pendants; however, under these conditions, 10-15% of the epoxy groups of the polymers were consumed during the polymerization by the reaction with the growing species. The polymerization by HI/I2 in CH2CI2 involved a long-lived propagating species, as indicated by a progressive increase in the molecular weight (M̄n) of the polymers with monomer conversion and their fairly narrow molecular weight distributions (M̄w/M̄n ∼ 1.6). The differences between the polymerizations of VPGE and p-isopropenylphenyl glycidyl ether, an α-methylstyrene-type counterpart of VPGE, were also discussed with an emphasis on the effects of the α-methyl group in the latter monomer.
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  • 125
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    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 2195-2206 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of interfacial polycondensation of bisphenol A with isophthaloyl chloride and terephthaloyl chloride in dichloromethane with triethylbenzylammonium chloride (TEBAC) as the catalyst was investigated via measurements of bisphenolate concentration by UV. The reaction was found to be second order with respect to bisphenolate. The dependence of the rate constant on stirring speed, amount of TEBAC, and reaction temperature was studied. The rate constant was increased with an increase of stirring speed, quantity of TEBAC added, as well as the reaction temperature. The activation energy was found to be 7.7 kcal/mol at a stirring speed of 700 rpm in the presence of 0.160 of TEBAC. The role of TEBAC was found to be interesting. It did not alter the equilibrium (the partition coefficient remained the same in the presence of TEBAC), but it did enhance the transfer rate of bisphenolate.
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  • 126
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    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 2165-2173 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Copolymerization of an isocyanide giving an insoluble homopolymer with another isocyanide giving a soluble homopolymer in ethanol solution using 0.5-1% of a nickel (II) catalyst in many cases gives a soluble copolymer containing pendant groups arising from both isocyanides. Thus, methyl isocyanide, which gives an insoluble homopolymer, gives chloroform-soluble copolymers incorporating 39-44% of pendant methyl groups when copolymerized with equimolar amounts of tert-butyl isocyanide or several aryl isocyanides. Similarly, cyclohexyl isocyanide, which also gives an insoluble homopolymer, gives chloroform-soluble copolymers incorporating 43-59% of pendant cyclohexyl groups when copolymerized with equimolar amounts of several aryl isocyanides. The compositions, chloroform solubilities, and polystyrene equivalent molecular weights are given for 33 different copolymers obtained by copolymerizations of various equimolar binary mixtures of the monomers CH3NC, (CH3)3CNC, cyclo-C6H11NC, C2H5NC, CH3CH=CHNC,(CH3)2C=CHNC, 2,4,6-(CH3)3C6H2CH=CHNC, C6H5CH(CH3)NC, CH2=CHNC, (CH3)3CCH=CHNC, C6H5NC, 2- and 4-CH3C6H4NC and 2-, 3-, 4-CH3OC6H4NC using the nickel (II) catalyst system.
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  • 127
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    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 2175-2183 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Previous work by a number of researchers has noted the presence of anhydride during the imidization step of polyimide polymer processing from diester-diacids and diamines. This has been often, and incorrectly, dismissed as being due to the reversion of the intermediate amide-acid. Comparison of the relative rates of reactions among model compounds demonstrates the intermediacy of anhydride in the imidization reaction. When creation of the anhydride is blocked, the production of amide-acid is greatly slowed. Infrared and NMR observations of mixtures of monomers confirm the production of anhydride as a necessary intermediate in the imidization reaction occuring during the production of polyimide polymers from diester diacids.
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  • 128
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    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 2221-2230 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Copolymers of ethyl acrylate (EA) with lithium acrylate (LiA) with relatively low contents of LiA units (up to 30%) were synthesized by alkaline hydrolysis of poly(EA). 13C-NMR spectra of these copolymers registered in a mixture of deuterated benzene with deuterated methanol (85:15 v/v) presented configurational splittings of the ester methylene, methylene main chain, and ester carbonyl group signals. Assignments of these splittings were made and Bernoulli statistics with a meso probability of 0.48 could fit both poly(EA) and poly(EA-co-LiA). Only the C=O signal of the copolymer was sensitive to sequence distribution and indicated that the LiA units have a tendency to be isolated on the chain. Two-dimensional HETCOR pulse sequence helped to assign the main chain proton spectrum.
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  • 129
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    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 2479-2491 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The cure of pyromellitic dianhydride-oxydianiline polyamic acid is compared with that of a model compound, diphenylcarbamido-dicarboxy-benzene, both having been synthesized in 1-methyl-2-pyrrolidinone (NMP). Laser interferometry and thermogravimetric analysis showed that, analog to the diamic acid model compound, the polyamic acid forms complexes with NMP (repeat unit/NMP: 1/4 and 1/2). Thermal stability of these complexes was found to be similar to the ones of the diamic acid model compound as revealed by comparison of decomplexation temperature-heating rate curves. Activation energies of the decomplexation processes for the diamic acid are given. Anhydride formation, a reaction found in the cure of the model compound to compete with imidization, takes place also during the polyamic acid cure at fairly low temperatures. The molecular weight drop due to chain scission resulting from anhydride formation was followed by viscometry.
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  • 130
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The asymmetric reduction of prochiral aromatic ketones with modified reagents prepared from sodium borohydride and carboxylic acids in the presence of both chiral polymers and relating low molecular weight compounds having (+)-5,6-exo-dihydroxybornyl derivatives was carried out. The enantioface differentiation took place effectively by raising the reaction temperature, and the highest enantiomeric excess was achieved at 10°C (24.3%) in the presence of the chiral polymers. A higher optical yield (87.8%) can be obtained in the asymmetric reduction by using the low molecular weight (+)-5,6-exo-diol compounds. The effect of the reaction temperature, solvents, and the advantages of the chiral polymer-bound reagents were also discussed.
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  • 131
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    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 2561-2568 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The polymerization of 1,3,6-trioxacyclooctane initiated by trityl salts with various counterions in CH2Cl2 was investigated. The reaction mixtures and the isolated polymers were analyzed by GPC (double detection - IR and UV at 254 nm),1H-, and13C-NMR spectroscopy. In the early stage of polymerization only oligomers (mainly cyclic) were formed. With longer reaction times, linear polymers (yield 86-94%, M = 70,000-80,000) were obtained. The concentration of each individual oligomer passed through a maximum and decreased, reaching its equilibrium concentration. The time interval necessary to reach the maximum concentration increased with n. The total concentration of the oligomers was 0.2 mol L-1 regardless of the initiator used. Conditions for polymerization with virtually no termination were found. Addition of p-methoxystyrene to the “living” polyacetals resulted in block copolymers. GPC,1H- and 13C-NMR and acidolytic degradation were used to prove the formation of AB block copolymers. The reactive alkoxycarbenium growing species are responsible for the formation of block polyacetal-polymethoxystyrene copolymer.
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  • 132
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    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 2605-2627 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of a series of vinylbenzyl ether macromonomers of poly(2,6-dimethyl-1,4-phenylene oxide) (PPO-VBE) with number average molecular weights between 1,000 and 27,000 and narrow molecular weight distribution is presented. The reactivity ratio r1 was determined for the comonomer pairs methyl methacrylate (MMA) and butyl methacrylate (BMA), respectively (M1), and PPO-VBE (M2) over the entire range of molecular weights of the macromonomer. r1 was determined by the single experiment intergrated equation. Since both the monomer and macromonomer present an induction period, it has been shown that the determination of r1 from one single point experiment is not correct. Accurate r1 values can be obtained from one single copolymerization experiment only when the comonomer conversions are determined at several different reaction times. The macromonomer reactivity (1/r1) increases with its molecular weight up to about 5,000-7,000. Above these values its reactivity decreases. An attempt to explain this behavior based on the kinetic excluded free volume effect is presented.
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    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 2643-2664 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The rapid defluorination of fluoropolymer surfaces by their exposure to a hydrogen plasma excited by an inductively coupled RF field has been studied using ESCA. The results are interpreted in terms of a reaction/depth profile; the reaction is not uniform with depth leading to the formation of an approximately 20 Å thick boundary layer of defluorinated material.
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    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 2711-2716 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Several new copolymers have been synthesized. Initial polycondensation of mixtures of aryl and arylalkyl carboxylic acids containing aromatic hydroxyl and amine substituents led to random copolyamides. Thermal cyclization of these prepolymers (inherent viscosities of about 0.2 dL/g) gave copolybenzoxazoles with inherent viscosities of about 1.4 dL/g. Thermal stability as measured by TGA was similar for the 1:1 copolymers and the homopolymers containing hydrocinnamic units; i.e., catastrophic decomposition occurred at 450°C. Copolymers with lower ratios of the hydrocinnamic units displayed greatly improved thermal stability while maintaining good molecular weight.
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  • 135
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cationic polymerization of 2-vinyloxyethyl glycidyl ether (VEGE), a vinyl ether with an epoxy group, was conducted with various initiators in CH2Cl2 in the temperature range from +15 to -78°C, and the possibility of its selective vinyl polymerization was investigated. BF3OEt2 polymerized both vinyl and epoxy groups of VEGE to yield polymers partially insoluble in organic solvents. HI/I2, iodine, and CF3SO3H gave soluble, low-molecular-weight oligomers with epoxy pendants. 1H-NMR structural analysis of the oligomeric products showed that the epoxy/vinyl ratio of the pendants decreases in the order: 100% epoxy ∼ CF3SO3H 〉 HI/I2 ∼ I2 ≫ BF3OEt2. Although HI/I2 or iodine mainly polymerized the vinyl group, the reaction of the vinyl ether-type growing end with an epoxy group of VEGE took place during the polymerization, so that the monomer conversion leveled off at about 40%.
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  • 136
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    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 2631-2642 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Using fluorescence spectroscopy and gel content measurement, the photolysis of simple polyurethanes based on methylene 4,4′-diphenyldiisocyanate (MDI) is shown to depend on both the flexibility and crystallinity of the polymer. Polyurethane films based on MDI and 1,12-dodecanediol (MDI-12) can be either annealed or quenched to yield a semicrystalline (as measured by DSC and X-ray diffraction) or amorphous film, respectively. In the case of the quenched (amorphous) film, photolysis yields an ortho photo-Fries product whereas the annealed (semicrystalline) film does not. Similarly, for a given photolysis time the annealed film generates a lower extent of crosslinked gel. In addition, photolysis of amorphous polyurethane films derived from MDI and ethylene oxide oligomers shows that for relatively inflexible polymers with only three ethylene oxide segments, little or no ortho photo-Fries rearrangement products are generated upon photolysis. In contrast, photolysis of more flexible polyurethane films with approximately 13 ethylene oxide linkages yields the ortho photo-Fries product. Apparently, for aromatic diisocyanate based polyurethanes, the extent and mechanism of degradation is directly dependent on the crystallinity and main-chain flexibility of the polymer.
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  • 137
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    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 3413-3422 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Previous studies of the photodegradation of bisphenol A polycarbonate (BPA PC) indicate that both alkyl side chain and ring oxidation play significant roles. In order to determine the relative importance of these two pathways in the photoyellowing that accompanies photodegradation, side chain free polycarbonates based on 3,3′-dihydroxydiphenyl ether were synthesized and tested. Both accelerated weathering experiments using a QUV test apparatus and outdoor weathering indicated that these polymers photoyellowed faster than BPA PC. This suggests that ring oxidation is an important source of photoyellowing of aromatic polycarbonates.
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  • 138
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Thermotropic liquid crystalline (LC) polyethers and copolyethers have been synthesized from 4,4′-dihydroxy-α-methylstilbene (HMS) and α,ω-dichlorooligo(oxyethylene)s having between 2 and 5 as well as 8.7 oxyethylene units. Copolyethers were prepared from a 1:1 mol/mol ratio of two dissimilar spacers. These polymers have been prepared by a phase transfer catalyzed (PTC) polyetherification of bisphenols with these electrophiles by utilizing 50 mol% tetrabutylammonium hydrogen sulfate per phenol group. Kinetic experiments with either 5 or 50 mol% catalyst vs phenol groups in the polyetherification of 4,4%-isopropylidenediphenol with 2-chloroethyl ether have shown that a change in catalyst primarily affects the rate of reaction, with 50 mol % being faster. The prepared polyethers and copolyethers are soluble in common organic solvents. Both polyethers and copolyethers are crystalline. Polymers prepared to contain tetraoxyethylene spacers exhibit monotropic LC behavior. Copolymers prepared to contain tri- and tetraoxyethylene spacers (1 : 1 mol/mol) [PE34] were the only polymers exhibiting enantiotropic LC behavior. Longer spacers tend to destabilize the phase transitions, as suggested by the dependence of thermal transition temperatures upon the differential scanning calorimeter rate. All prepared polymers act as podants in solution, measured by picrate extraction experiments. Solid state complexes have been prepared from the polymer with a pentaoxyethylene spacer [PE5] and PE34 with LiCF3SO3. PE5 can dissolve LiCF3SO3 in the range of 0.21-2.2 mol salt/mol polymer (m.r.u.) [S/P] without the observation of free salt. PE5 complexes of/or below S/P of 0.43, upon annealing at room temperature, exhibited the two melting transitons observed in the polymer alone. PE5 complexes of/or above S/P of 0.77 only exhibited a Tg. The Tg of PE5 complexes were found to change nonlinearly with S/P, while Tm1 changed linearly. Tm2 was independent of S/P. Only one complex with PE34 gave two transitions (Tm2,Ti) in dynamic DSC experiments. Other PE34 complexes followed a behavior similar to PE5 complexes.
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  • 139
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    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 2847-2870 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A systematic study has been made on the functions of external Lewis base (Be, methyl-p-toluate, MPT) and internal Lewis base (Bi, ethyl benzoate, EB) for the CW-catalyst system MgCI2/EB/PC/AlEt3/TiCl4-AlEt3/MPT (PC, p-cresol). Bi is a nonstereoselective modifier. It increases the active site concentrations and rate constants of propagation, kp, of both the isospecific and nonspecific sites, and thus the productivities of the stereoregular and irregular polypropylenes by five- to tenfold. It seems that Bi complexes with the MgCl2 support to lower the electronegativity of the surface Mg atoms. It also acts to lower the rate constant of chain transfer to aluminum alkyl, kAtr, by two- to fourfold. The action of Be is highly stereospecific. The isotacticity index of polypropylene is ≫ 95% in the presence of Be but ≪ 68% without it. Addition of Be decreases nonspecific [Ti*]a by about (11 ± 2)-fold; there is only about a twofold reduction of the isospecific [Ti*]i. It decreases kp,a about three times but has no effect on kp,i, so that the latter is (21 ± 4) times the former. Be decreases kAtr,i for transfer with aluminum alkyl much more than it does to kAtr,a; but it does not affect the rates of chain transfer with monomer and by β-hydride elimination or the rate of catalyst deactivation. The number of active sites without Be is [Ti*]i = 15% and [Ti*]a = 55% for a total of 70%. In the presence of Be they are both about 6%. Optimum performance in propylene polymerizations requires both Bi and Be in the case of the CW-catalyst.
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    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 2925-2929 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 141
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    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 2941-2952 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Poly(L-trans-3-ethylproline), L-PT3EP, and poly(D-trans-3-ethylproline), D-PT3EP, were prepared by ring opening polymerization of the corresponding N-carboxyanhydrides (NCA) using triethylamine as an initiator. Using circular dichroism spectroscopy, it was shown that the incorporation of an ethyl group at the 3 position of the pyrrolidine ring caused a noticeable change in the conformational behavior of the polymer in solution. The ethyl group limited to some extent rotation of the polymer chain around the C——CO bond and prevented the mutarotation between the two forms found in poly-L-proline polymers.
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    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 2963-2985 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Asymmetric linear and cross-linked imidazole-containing polymers were prepared from 1-[2(S)-methylbutyl]-4-vinylimidazole and 1-[2(S)-methylbutyl]-5-vinylimidazole. The esterolytic reactions of these linear and cross-linked asymmetric polymers with the enantiomeric substrates (R)- and (S)-4-(3-methylpentadecanoyl)-3-nitrobenzoic acid, (R)- and (S)-S-3Me15, were studied by measuring the pseudo-first order kinetics of the solvolysis of these enantiomeric substrates in the presence of these asymmetric polymers. The linear homopolymers and copolymers of 1-[2(S)-methylbutyl]-4- and 5-vinylimidazole showed hydrophobic and electrostatic effects in the solvolysis of the enantiomeric substrates with these linear asymmetric polymers. Cross-links were introduced into these asymmetric polymers to increase the rigidity and reduce the number of conformations available to the polymer. The reduced conformational mobility was expected to enhance any enantioselectivity in the solvolysis of the enantiomeric substrates with these polymers. Using these cross-linked polymers, hydrophobic interactions were observed in the solvolysis of a series of substrates with increasing alkyl chain length. Also, on changing the polarity of the solvent, a bell-shaped rate profile was observed in the solvolysis of the long chain substrate S-3Me15. This effect was attributed to a combination of the coiling of the cross-linked polymer chains and hydrophobic interactions with the substrate on changing solvent polarity. Even with the increased rigidity of these cross-linked polymers, no significant enantioselectivity in the solvolysis of the enantiomeric substrates was observed. So, neither the linear nor the cross-linked asymmetric polyvinylimidazoles showed enantioselectivity in the solvolysis of these enantiomeric substrates. In this case, the hydrophobic interactions and the reduced conformational mobility through crosslinking were not strong enough to bring about enantioselectivity in the solvolysis of these enantiomeric substrates.
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    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 3015-3024 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ion conductivity of poly(ethylene oxide) (PEO)-based polyurethane networks containing alkali metal salts has been investigated. Consequently, it has been revealed that the conductivity is dependent on the following parameters: lattice energy of the alkali metal salt, concentration of alkali metal salt, and the cross-linking density of the network polymer (which is a function both of the amount of cross-linking agent and the molecular weight of PEO). Under optimal conditions, the conductivity at ambient temperature corresponded to 2.51 × 10-5 Scm-1, which is greater than that of a typical alkali metal-PEO system by a factor of about 102 to 103. Moreover, from the standpoint of the application to electrochromic displays (ECD), tensile bond strength between the polymer electrolytes and tungsten trioxide (WO3), which is the most promising electrochromic material, has been evaluated. The bonding strength of the bond of WO3 with the present electrolyte has been found to be much larger than that of the alkali metal-PEO system.
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    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 3063-3077 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Three methods to introduce photodimerizable styrylpyridinium or styrylquinolinium groups to methacrylate polymers are described. Among these, copolymerization of methacrylate monomers with methacrylated styrylpyridine or styrylquinoline offered the most convenient procedure to prepare photosensitive polymers because of the excellent solubility of the polymers having the photofunctional groups in high content. Subsequent treatment with p-toluenesulfonic acid to quaternize the pyridine or quinoline moiety made the polymer highly photosensitive. The polymers having a styrylquinolinium group were found to be sensitive to 488 nm light of an Ar laser, and the sensitivity was about 3 mJ/cm2 when the content of the photosensitive group was 15 mol %.
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    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 3089-3103 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 2-Methoxy-6-ethoxy-5-cyano-3,4-dihydro-2H-pyran (1a), 2-isobutoxy-6ethoxy-5-cyano-3,4-dihydro-2H-pyran (1b), and 2,6-diethoxy-3-methyl-5-cyano-3,4-dihydro-2H-pyran (1c) were prepared by (4 + 2) cycloaddition reaction of ethyl α-cyanoacrylate with the corresponding vinyl ethers. Compounds 1a-c were ring-open polymerized by cationic catalyst to obtain alternating head-to-head (H—H) copolymers. For comparison, head-to-tail (H—T) copolymer 3a was also prepared by free radical copolymerization of the mixture of the corresponding monomers. The H-H copolymer exhibited minor differences in its 1H-NMR and IR spectra, but in the 13C-NMR spectrum significant differences were shown between the H—H and H—T copolymers. Glass transition temperature (Tg) of H—H copolymer was higher than that of the corresponding H—T copolymer, but thermal decomposition temperature of the H—H copolymer was lower than that of the H—T copolymer. Compounds 1a and 1b copolymerized well with styrene by cationic catalyst, but compound 1c failed to copolmerize with styrene. All of the H-H and H-T copolymers were soluble in common solvents and the inherent viscosities were in the range 0.2-0.5 g/dL.
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  • 146
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    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 3127-3141 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Isobutylene has been polymerized in a continuous stirred tank reactor using a catalyst system comprised of 1-bromoadamantane and diethylaluminum chloride. The polymerization was carried out in hexane solvent at -15 to -27°C and gave 100% conversion to polyisobutylene (PIB) of 1000-3000 Mw. The results of pyrolysis-gas chromatography-mass spectrometry analyses are consistent with a mechanism involving the formation of the adamantyl cabocation and its addition to an isobutylene molecule to initiate polymerization. 13C-NMR analyses show that the PIB products contain R2C—CR2 and R2C—CHR olefin types. Information on the nature of these olefins and the route to their formation has been developed.
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  • 147
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    Keywords: Chemistry ; Polymer and Materials Science
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    Topics: Chemistry and Pharmacology
    Notes: The inclusion polymerization of 1,3-butadiyne was studied at different temperatures using deoxycholic acid and apocholic acid as the host molecules. The polymers that resulted consist of predominantly 1,4-structure rather than 1,2 or acene structure as confirmed by both IR and Raman spectroscopies. The poly(1,3-butadiyne)s were found to possess unique optical properties and high electric conductivity as compared with those prepared by the usual polymerization methods.
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  • 148
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    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 3205-3214 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of dithiocarbamate salts with α-haloketones is extended to (i) dithiocarbamate salts with bis(α-haloketones), (ii) bis(dithiocarbamate salts) with α-haloketones, and (iii) bis(dithiocarbamate salts) with bis(α-haloketones). Both (i) and (ii) give bis([3H]-thiazole-2thiazole-2-thiones) in high yields, and (iii) gives the corresponding polymers which are described and characterized.
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  • 149
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    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 3231-3239 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The encapsulation of fine inorganic powder was carried out with the soapless emulsion polymerization of methyl methacrylate in water in the presence of the powder, a layer of surfactant being adsorbed. The powder used was titanium dioxide. Surfactants added prior to the polymerization were sodium dodecyl sulfate, dodecyltrimethyl ammonium bromide, and polyoxyethylene sorbitan mono-oleate. The encapsulation state of the powder with polymer was closely related to the amount of surfactant adsorbed on the powder; and an amount of adsorption above a certain value was necessary for uniform encapsulation. Ionic surfactants were more useful than nonionic in the surfactants used, and could be adsorbed utilizing the electrostatic interaction between powder and the ionic end group. The combination of electric charges between the ionic end groups of surfactant and initiator was found to influence the molecular weight of capsulating polymer.
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  • 150
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    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 3267-3281 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new route to polyurethanes containing nucleic acid base derivatives as grafted pendants have been established. The method is based on the grafting of 2-(thymin-1-yl)propionic acid (TPA) or 2-(adenin-9-yl)propionic acid (APA) onto amino functionalized polyurethane, poly[2-amino-2-methyl-1,3-propylene methylene bis(4-phenyl carbamate)] (PU-NH2, IX) at the primary amino group by the N-hydroxy compound of active ester technique. Two novel polymer models of polynucleic acid - poly[2-(2′-(thymin-1′-yl) propionamido)-2-methyl-1,3-propylene methylene bis(4-phenylcarbamate)] (PU-NHT, X) and poly[2-(2′-(adenin-9′-yl)propionamido)-2-methyl-1,3-propylene methylene bis(4-phenylcarbamate)] (PU-NHA-40, XI) - were obtained. The amino functional polyurethane was prepared by the following three step reactions; (1) Selective N-protection of N-benzyloxycarbonyloxy-5-norbornene-2,3-dicarbonimide (CbzONB) with 2-amino-2-methyl-1,3-propanediol gave the N-protecting diol monomer 2-benzyloxycarbonylamino-2-methyl-1,3-propanediol (CbzAMP); (2) N-Protecting polurethane poly(2-benzyloxycarbonylamino-2-methyl-methyl-1,3) propylene methylene bis(4-phenylcarbamate) (PU-NHCbz, VIII) was obtained by the polyaddition of 4,4′-diphenyl-methane diisocyanate (MDI) with CbzAMP. (3) Deprotection of PU-NHCbz produced amino polyurethane PU-NH2. Prior to polymer synthesis, the amidation of APA with 3-aminoheptane or diethylamine were carried out as a model reaction study and the related monomer model compounds were prepared by the same methods.
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  • 151
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    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 669-673 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The decomposition ratio of cation exchange resin (sulfonated ST-DVB copolymer) after pyrolysis is only 50 wt%, while that of ST-DVB copolymer is 90 wt%. Fundamental experiments were performed to investigate the reason for the low decomposition ratio of the former.The cation resin consists of base polymer (ST-DVB copolymer) and functional sulfonic acid groups. Chemical analyses of the pyrolysis products showed that most of the functional groups decomposed at about 300°C and generated SO2 gas. However, only a small amount of the base polymer was pyrolyzed even at 600°C and the total decomposition ratio was only 50 wt%. The XPS studies on the residue showed that 35% of the functional sulfonic acid groups was converted to sulfonyl and sulfur bridges between the base polymers during pyrolysis. These bridges made the base polymers, namely ST-DVB copolymer, thermally stable.
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  • 152
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    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 703-709 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Aqueous polymerization of methyl methacrylate in visible light was studied using isoquinoline-sulphur dioxide (IQ-SO2) charge-transfer complex as the photoinitiator. Analysis of kinetic and other data indicate that the polymerization proceed via a radical mechanism and the termination is dependent on the initiator concentration. Chain-termination via degradative chain (initiator) transfer appears to be predominant here.
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    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 731-734 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 735-737 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 3495-3498 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    Journal of Polymer Science: Polymer Letters Edition 25 (1987), S. 161-167 
    ISSN: 0887-6258
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    Journal of Polymer Science: Polymer Letters Edition 25 (1987), S. 187-191 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Topics: Chemistry and Pharmacology
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    Journal of Polymer Science: Polymer Letters Edition 25 (1987), S. 201-203 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Topics: Chemistry and Pharmacology
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    Journal of Polymer Science: Polymer Letters Edition 25 (1987), S. 209-213 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Topics: Chemistry and Pharmacology
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    Journal of Polymer Science: Polymer Letters Edition 25 (1987), S. 79-82 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Journal of Polymer Science: Polymer Letters Edition 25 (1987), S. 84-85 
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    Journal of Polymer Science: Polymer Letters Edition 25 (1987), S. 105-110 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Topics: Chemistry and Pharmacology
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    Journal of Polymer Science: Polymer Letters Edition 25 (1987), S. 267-267 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Journal of Polymer Science: Polymer Letters Edition 25 (1987), S. 383-387 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Topics: Chemistry and Pharmacology
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    Journal of Polymer Science: Polymer Letters Edition 25 (1987), S. 401-402 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Journal of Polymer Science: Polymer Letters Edition 25 (1987), S. 403-404 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Journal of Polymer Science: Polymer Letters Edition 25 (1987), S. 423-423 
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    Keywords: Chemistry ; Polymer and Materials Science
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  • 168
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    Journal of Polymer Science: Polymer Letters Edition 25 (1987), S. 447-449 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    Journal of Polymer Science: Polymer Letters Edition 25 (1987), S. 461-461 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Journal of Polymer Science: Polymer Letters Edition 25 (1987), S. 463-464 
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    Journal of Polymer Science: Polymer Letters Edition 25 (1987), S. 471-475 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    Journal of Polymer Science: Polymer Letters Edition 25 (1987), S. 495-501 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 5 Ill.
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    Journal of Polymer Science: Polymer Letters Edition 25 (1987), S. 503-507 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    Journal of Chemometrics 1 (1987) 
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    Journal of Chemometrics 1 (1987), S. 1-2 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    Journal of Chemometrics 1 (1987), S. 3-6 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 178
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    Journal of Chemometrics 1 (1987), S. 7-18 
    ISSN: 0886-9383
    Keywords: Kalman filter ; Calibration ; Curve resolution ; Parameter estimation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The application of the Kalman filter to the solution of a variety of problems in analytical chemistry is reviewed. Five examples are selected from the literature to illustrate the use of Kalman filtering techniques for obtaining least-squares estimates fo several parameters of analytical importance. These examples include multicomponent curve resolution and concentration estimation, correction for variable background responses, calibration with drift compensation, and estimation of kinetic parameters for first-order reactions and for heterogeneous charge-transfer reactions. An adaptive Kalman filtering technique is required for the solution of the background correction problem, and the extended Kalman filter algorithm is required for the solution of the nonlinear kinetic problems. For each case, the results that were obtained are summarized, and some advantages of Kalman filtering over traditional least-squares approaches are discussed.
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    Journal of Chemometrics 1 (1987), S. 19-31 
    ISSN: 0886-9383
    Keywords: Calibration ; Indirect calibration ; Multivariate ; Matrix decomposition ; PLS ; PCR ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Partial least squares (PLS) modeling is an algorithm for relating one or more dependent variables to two or more independent variables. As a regression procedure it apparently evolved from the method of principal components regression (PCR) using the NIPALS algorithm, which is similar to the power method for determining the eigenvectors and eigenvalues of a matrix. This paper presents a theoretical explanation of the PLS algorithm using singular value decomposition and the power method. The relation of PLS to PCR is demonstrated, and PLS is shown to be one of a continuum of possible solutions of a similar type. These other solutions may give better prediction than either PLS or PCR under appropriate conditions.
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  • 180
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    Keywords: Principal component analysis ; Singular value decomposition ; Factor analysis ; Rank determination ; Eigenvector analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The distribution of error eigenvalues resulting from principal component analysis is deduced by considering the decomposition of an error matrix in which the errors are uniformly distributed. The derived probability function is \documentclass{article}\pagestyle{empty}\begin{document}$$ P(\lambda ^0 _j) = N(r - j + 1)(c - j + 1) $$\end{document} Where λ0j is the jth error eigenvalue, r and c are the numbers of rows and columns in the data matrix, and N is the normalization constant. This expression is tested and validated by investigations involving model data. The distribution function is used to determine the number of factors responsible for various sets of spectroscopic data taken from the chemical literature (including nuclear magnetic resonance, infrared and mass spectra).
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  • 181
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    Keywords: Curve resolution ; Liquid chromatography ; Accuracy ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The performance of curve resolution and iterative target transformation curve resolution in quantitative liquid chromatography with a diode array detector is evaluated. Quantitative accuracy of the elution profiles obtained for two- and three-component mixtures has been evaluated as a function of spectral similarity, chromatographic resolution and ratio of the peak areas, using a number of simulations analysed by an analysis of variance. The results obtained by simulation are compared and validated with the results obtained for the separation of phenylene diamines in reversed phase liquid chromatography and proteins in gel permeation liquid chromatography. The results that were obtained are summarized and the chromatographic implications are discussed.
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  • 182
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    Keywords: Multi-way array ; Multiorder array ; Principal components ; PLS ; Multivariate calibration ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Lohmöller-Wold decomposition of multi-way (three-way, four-way, etc.) data arrays is combined with the non-linear partial least squares (NIPALS) algorithms to provide multi-way solutions of principal components analysis (PCA) and partial least squares modelling in latent variables (PLS).The decomposition of a multi-way array is developed as the product of a score vector and a loading array, where the score vectors have the same properties as those of ordinary two-way PCA and PLS. In image analysis, the array would instead be decomposed as the product of a loading vector and an image score matrix.The resulting methods are equivalent to the method of unfolding a multi-way array to a two-way matrix followed by ordinary PCA or PLS analysis. This automatically proves the eigenvector and least squares properties of the multi-way PCA and PLS methods.The methodology is presented; the algorithms are outlined and illustrated with a small chemical example.
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    Journal of Chemometrics 1 (1987), S. 73-73 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Journal of Chemometrics 1 (1987), S. 75-75 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
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    Journal of Chemometrics 1 (1987), S. 74-74 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
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    Journal of Chemometrics 1 (1987) 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
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    Journal of Chemometrics 1 (1987), S. 77-77 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
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    Topics: Chemistry and Pharmacology
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  • 188
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    Journal of Chemometrics 1 (1987), S. 79-90 
    ISSN: 0886-9383
    Keywords: Numerical deconvolution ; Peak resolution ; Peak separation ; Iterative deconvolution ; Jansson's method ; Super-resolution ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Severely overlapped gas chromatographic peaks can be resolved using Jansson's method. Jansson's method is an iterative nonlinear deconvolution technique and consists of Van Cittert's algorithm with the relaxation factor a function of the kth estimate of the peak shape. The maximum peak amplitude of the instrument and peak non-negativity serve as constraints to improve the peak estimate. Super-resolution is achieved without significantly degrading the chromatogram signal-to-noise ratio. The method only requires a knowledge of the instrument impulse response function and maximum peak height.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 189
    ISSN: 0886-9383
    Keywords: NIR ; Fast Fourier transform ; Principal component analysis ; Discrimination ; Baking quality ; Wheat ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Digitalized continuous near infra-red reflectance (NIR) spectra are composed of a great number of data which must be reduced for microcomputer mathematical treatment. The sequence ‘fast Fourier transform preceding principal component analysis’ was tested to perform data size reduction without a large loss of information. The method was applied on a collection of wheat spectra composed of 351 data. Ten resulting data, which described 99.5% of the total variance, were kept. The relevance of the method was estimated by the ability of the resulting data (i) to regenerate the original signal, and (ii) to discriminate the baking quality of the wheat by stepwise multiple discriminant analysis. The average difference between initial and regenerated spectra was -2.4 × 10-3 log (1/R) units and the standard deviation was 1.16 × 10-3 log (1/R) units. The discrimination treatments gave 89.9% of well classified samples for the calibration test and 90.5% for the prediction test. The application of these mathematical treatments to other continuous signals is discussed.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 190
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    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 1 (1987), S. 91-101 
    ISSN: 0886-9383
    Keywords: Factor analysis ; Retention indices ; Model ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Retention indices for 18 monomeric stationary-phase solvents and 33 organic solutes are factor analyzed. Six factors reproduce the data matrix near experimental error. The solvents diglycerol and zonyl E-7 are shown to be highly unique, whereas none of the solutes behaves uniquely. Combination sets of solvent vectors and of solute vectors from the data matrix lead to models having errors within experimental error. Basic factors which might influence the solute - solvent interactions are identified by the least-squares method of target testing. For the solvents, a number of properties, including McReynolds' constants and molecular weight, test successfully. For the solutes, carbon number and group dipole moment are representative properties which test successfully. The best combination of solvent basic factors gives errors about twice the experimental error. Combination sets composed only of McReynolds' constants do not model the data well.
    Additional Material: 6 Tab.
    Type of Medium: Electronic Resource
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  • 191
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    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 1 (1987), S. 111-120 
    ISSN: 0886-9383
    Keywords: Principal component analysis ; Submatrix analysis ; Spectroscopy ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In the treatment of spectroscopic data by principal component analysis, correct determination of the dimensionality of the data is essential. Submatrix analysis, which involves preliminary analysis of subsets of the data matrix, is described, and shown to be valuable in determining both the size of the factor space and estimates of equilibrium constants in the system, even for data containing abnormally large experimental error.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 192
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    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 1 (1987), S. 135-135 
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 193
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    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 1 (1987), S. 136-136 
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 194
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 1 (1987), S. 121-134 
    ISSN: 0886-9383
    Keywords: Multivariate calibration ; NIR ; Cluster analysis ; Experimental design ; Sample selection ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A procedure for selecting samples to use in multivariate calibration, inspired by a paper by Zemroch, is proposed. The method developed is designed for multicollinear data and is based on cluster analysis. It selects among availabe spectra the samples to submit to chemical analysis and calibration. The method is tested on an example from NIR spectroscopy of biscuit dough pieces.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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  • 195
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 1 (1987), S. 136-136 
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 196
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 1 (1987) 
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 197
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 1 (1987), S. 137-137 
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 198
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    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 1 (1987), S. 157-173 
    ISSN: 0886-9383
    Keywords: Gas chromatography ; Simplex ; Barycentric co-ordinates ; Discriminant analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This paper proposes an elegant, yet straightforward, model for classifying linear mixtures. A linear mixture is defined as a random vector y in which the variable are a (non-negative) weighted average of corresponding variables, assumed to characterize g component groups. These weights are referred to as ‘mixing proportions’. The model seeks to identify the mixture constituents and estimate the mixing proportions. It is demonstrated within the context of high resolution gas chromatography and the problem of identifying the constituents in polychlorinated biphenyl mixtures.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 199
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 1 (1987), S. 175-183 
    ISSN: 0886-9383
    Keywords: Deconvolution ; Jansson's method ; Peak resolution ; Numerical deconvolution ; Super resolution ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In a previous paper,1 Jansson's method was used to deconvolve overlapped gas chromatographic peaks. It was found that this method gave improved performance over conventional techniques such as perpendicular drop and shoulder quantitation.2,3 This paper will present the results of a comprehensive test of Jansson's method using several sample mixtures. These results will be compared to what can be obtained by using shoulder quantitation, perpendicular drop or an instrument with a longer column. A relatively large number of tests will be performed for each of the four mentioned methods of peak resolution, so there will be a reasonable statistical basis for the goodness of Jansson's method to resolve fused gas chromatographic peaks for a given set of instrument conditions. A brief review of Jansson's method and the modeling of a gas chromatographic process will also be presented.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 200
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    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 1 (1987), S. 139-155 
    ISSN: 0886-9383
    Keywords: Chemical information systems ; Machine-readable structure representation ; Registration search ; Structure search ; Substructure search ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This paper decribes the development and current state-of-the-art in computerized systems for the storage and retrieval of chemical structure information. The main types of machine-readable structure representation  -  fragmentation codes, linear notations and connection tables  -  are described, together with the retrieval algorithms which are used to provide structure and substructure search facilities. Current research work in chemical structure retrieval includes the development of techniques for the representation and searching of the generic structures which occur in chemical patents, for searching files of three-dimensional structures, for ranking searches designed to identify compounds structurally similar to a given query compound, and the use of parallel computers to increase the efficiency of substructure searching. Chemical structure handling techniques are also applicable in a range of application areas, including chemical reaction indexing, computer-aided synthesis design and structure elucidation, and substructural analysis methods for the study of quantitative structure - activity relationships.
    Type of Medium: Electronic Resource
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