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  • 1995-1999  (5,106)
  • 1980-1984
  • 1995  (5,106)
  • Polymer and Materials Science  (4,710)
  • Physical Chemistry  (241)
  • crystal structure  (158)
  • Nuclear reactions
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  • 1995-1999  (5,106)
  • 1980-1984
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  • 1
    ISSN: 1349-9432
    Keywords: organic crystal ; racemic form ; second-harmonic generation ; refractive index ; nonlinear optical coefficient ; crystal structure ; oriented-gas model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Linear and nonlinear optical properties of racemic (±)2-(α-methylbenzylamino)-5-nitropyridine ((±)MBANP) single crystals have been comprehensively investigated and compared with those of the enantiomorph (–)2-(α-methylbenzylamino)-5-nitropyridine ((–)MBANP) crystals. (±)MBANP crystal exhibits very high chemical and physical stability, but relatively small nonlinear optical coefficients (d31 = 6.8 pm/V, d32 = 4.7 pm/V, d33 = 0.84 pm/V). A comparison between the nonlinear optical coefficients of (±)MBANP and (–)MBANP demonstrates the validity of the oriented-gas model in molecular crystals that neglects all the contributions from intermolecular interaction.
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  • 2
    ISSN: 1572-8854
    Keywords: Amines ; crystal structure ; pentacycloundecane-8,11-dione
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal structures of three compounds formedvia nucleophilic attack of a heterocyclic secondary amine on PCU-8,11-dione, with the concomitant intramolecular attack of one keto oxygen on the carbon of the other ketone, are presented. In all three compounds, the bridging oxygen contains substantial p-character, and the bonds to the “attacking” nitrogen are significantly shorter than would be expected.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical crystallography 25 (1995), S. 57-62 
    ISSN: 1572-8854
    Keywords: phase diagram ; buffered chloroaluminate ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The phase diagram of the buffered neutral aluminum chloride + 1-ethyl-3-methyl-1H-imidazolium chloride + sodium chloride (AlCl3-EMIC-NaCl) ternary melt system can be represented by a binary phase diagram composed of (EMI)AlCl4 and NaAlCl4. In the binary phase diagram, the salts are liquid at, or near, room temperature for a wide range of compositions. At the 1∶1 composition, the congruently melting compound (EMI)(Na)(AlCl4)2 with m.p.=36.7°C is formed. Crystals of this mixed organic-inorganic salt were grown for single crystal x-ray diffraction analysis. The compound crystalizes in the space group $$P\bar 1$$ with lattice parametersa=10.321(1) Å,b=10.895(3) Å,c=9.284(4) Å, α=98.31(2)°, β=100.83(4)°, γ=101.95(3)°. Data collected at −120°C gave final residuals ofR=0.037 andR w=0.045 using 2713 observed reflections. The packing diagram reveals Na+ ion zig-zag chains running along thea-axis with each Na+ surrounded by four AlCl 4 − units, reminiscent of NaAlCl4. The AlCl 4 − ions form a distorted square planar coordination sphere around Na+ at an average Na−Al distance of 3.76(4) Å. Using a sodium ionic radius of 1.16 Å, a new AlCl 4 − ionic radius of 2.60 Å is calculated. This radius is 0.21 Å shorter than the reported thermodynamic radius.
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  • 4
    ISSN: 1572-8854
    Keywords: Calixarene ; complex ; crystal structure ; chirality
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The title compound was obtained by treatment ofp-tert-butylcalix[4]arene with (+) camphorsulfonyl chloride in triethylamine and toluene. A (1∶2) complex with toluene has been found. Its structure has been determined by X-ray crystallography. Crystals are triclinic with space group P1,a=16.426(3),b=18.553(3),c=13.661(2) Å, α=94.78(2), β=110.76(2), γ=72.83(2)°,V=3720(2) Å3,d c =1.127 g/cm3 Z=2. Refinement based on 10495 observed reflections led to a finalR value of 0.100. The two independent molecules of calixarene in the asymmetric unit are in the cone conformation and the calixarene cavities are empty. The guest molecule occupies the interhost space. The norborane skelton of (+) camphorsulfonyl group is the same as ones found in literature. Only van der Waals interactions exist between the host and the guest molecules.
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  • 5
    ISSN: 1572-8854
    Keywords: Mercury(II) terpyridine complex ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract [Hg(terpy)2](CF3SO3)2·0.5(CH3)2CO crystallizes in the triclinic $$P\bar 1$$ space group witha=14.631(6),b=15.258(4),c=18.785(7) Å, α=69.66(2), β=70.72(1), γ=88.55(1)°. The crystal structure consists of two independent [Hg(terpy)2]2+ cations, four trifluoromethanesulfonate anions and an acetone molecule in the asymmetric unit. Each mercury atom is coordinated by two tridentate terpyridine ligands forming an irregular six-coordination polyhedron. The Hg−N bond lengths range from 2.27(2) to 2.53(2) Å.
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  • 6
    ISSN: 1572-8862
    Keywords: Palladium ; gold ; cluster ; phosphine ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract [Au2Pd14(μ3-CO)7(μ2-CO)2(PMe3)11](PF6)2 has been synthesized from [Pd8(CO)8(PMe3)7] and AuCl(PCy3) in the presence of TIPF6. It has been characterised on the basis of mass spectrometry, infrared and NMR spectroscopy, and a single crystal X-ray diffraction study. The structure is based on a palladium-centered Au2Pd11 icosahedron which shares an edge with a Pd5 trigonal bipyramid.
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  • 7
    ISSN: 1572-8862
    Keywords: Silver ; iron ; carbonyl ; cluster ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The oxidation of the [Fe(CO)4]2− dianion with Ag+ salts occurs through a particularinner-sphere mechanism, which involves an intermediate cascade of silver clusters stabilized by Fe(CO)4 ligands. The last detectable Ag-Fe cluster of the sequence is the [Ag13{μ-Fe(CO)4}8]3− trianion, which has been selectively obtained by using ca. 1.7 equivalents of Ag+ per mole of [Fe(CO)4]2−. The [Ag13{μ-Fe(CO)4}8]3−- trianion has been isolated in a crystalline state with several quaternary cations, and has been characterized by X-ray diffraction studies of its bis(triphenylphosphine)iminium salt. [N(PPh3)2]3 [Ag13{μ 3-Fe(CO)4}8]·2(CH3)2CO, monoclinic, space group P21 (No.4),a = 16.284(2) Å,b =18.767(5) Å,c = 25.905(4) Å,β = 90.46(1)°,V = 7916(3) Å3,Z = 2,R = 0.0324. The molecular structure of the anion consists of a centered cuboctahedron of silver atoms with the triangular faces capped by Fe(CO)4 units. Chemical reduction of ( Ag13{μ 3-Fe(CO)4}8]3− affords the corresponding [Ag13{μ 3-Fe(CO)4)8]4−, which in turn gives [Ag13{μ 3-Fe(CO)4)8]5− and [Ag6{μ 3-Fe(CO)4}4]– upon further reduction. Electrochemical investigations confirm the reversibility of the [Ag13{μ 3-Fe(CO)4}8]3−/4− redox change. Furthermore, in spite of some electrode poisoning effects, evidence of the existence of the [Ag13{μ 3-Fe(CO)4}8]5− pentaanion was obtained. The yet structurally uncharacterized [Ag6{μ 3-Fe(CO)4)4]2− dianion is quantitatively obtained by reaction of [Fe(CO)4]2− with ca. 1.5 equivalents of Ag+ or by addition of one equivalent of Ag+ to solutions of the [Ag5{Fe(CO)4}4]3− trianion. All attempts to isolate its quaternary salts as crystalline materials failed owing to formation of amorphous insoluble precipitates. The above series ofμ 3-Fe(CO)4 octa-capped cuboctahedral Ag13 clusters can be envisioned as the Ag+ . Ag and Ag− cryptates of the [Ag12{μ}3-Fe(CO)4}8]4− cryptand. respectively.
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  • 8
    ISSN: 1572-8862
    Keywords: Osmium ; unsaturated cluster ; ortho-metallation ; siloxyl ligand ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The reaction of Os3(CO)10(NCMe)[Si(OMe)3](μ-H),1, with PMe2Ph yielded the new complex Os3(CO)10(PMe2Ph)[Si(OMe)3](μ-H),2 by substitution of the MeCn ligand with the phosphine ligand. When heated to 125°C compound2 was decarbonylated and transformed into the new unsaturated cluster complex Os3(CO)8[μ-PMe2(C6H4)][Si(OMe)3](μ-H)2,3 in 54% yield. Compound3 was characterized by a single crystal X-ray diffraction analysis, osmium bonds. The phenyl ring of the phosphine ligand has undergoneortho-metallation by a neighboring metal atom. A terminally coordinated Si(OMe)3 ligand is coordinated to the third osmium atom. The cluster is unsaturated by the amount of 2 electrons, and there is an open coordination site on the siloxyl substituted osmium atom that is partially filled by a weak interaction with one of the π-bonds of theortho-metalled phenyl ring. Complex3 reacts with CO at 1 atm to reform compound2 in 85% yield in 5 h at 40°C. Crystal Data: for3: space group = P21/n,a = 9.911(2) Å,b = 18.451(6) Å,c = 14.872(2) Å,β = 95.64(2)°,Z = 4, 1994 reflections,R = 0.028.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Journal of cluster science 6 (1995), S. 549-566 
    ISSN: 1572-8862
    Keywords: Molybdenum ; tungsten ; di-μ-oxo bridge ; sexadentate ligands ; asymmetric distortion ; stereoselectivity ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Binuclear oxomolybdenum(V) and oxotungsten(V) complexes of the type, [M 2(O)2(μ-X)(μ-X 1)]”, where M=Mo, W;X.X 1=O, S; L=edta, pdta (n=2-), tpen, tppn (n=2+) (edta4– =ethylenediaminetetraacetate(4–), pdta=R- orR,S-propylenediaminetetraacetate(4–), tpen=N,N,N 1,N1-tetrakis(2-pyridyhnethyl)-ethylenediamine, and tppn=R- orR,S-N,N,N 1,N1-tetrakis(2-pyridylmethyl)-propylenediami ne) are reviewed with respect to their preparation, structure, spectroscopic properties, reactivities, and in particular asymmetric distortion around the bicyclo [4.1.1 ] type core and stereoselectivity related to this distortion,
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  • 10
    ISSN: 1572-8854
    Keywords: Molecular mechanics ; molecular dynamics ; MNDO ; CMPO ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal structure of N,N-diisobutyl-2-(octylphenylphosphinyl)acetamide, or CMPO was recently determined. The compound crystallizes in the space group P21/c witha=13.446(6),b=22.280(7),c=17.217(7) Å, β=92.07(4)°, andD calc=1.05 g/cm3 forZ=8 @20°C). Molecular mechanics, molecular dynamics, and MNDO calculations were also performed on CMPO utilizing the SYBYL1 suite of programs. The results from these calculations are compared to the crystal structure and to similar calculations performed on CMPO using ALCHEMY2,3. In general, the results from the calculations agree fairly well with the parameters from the crystal structure.
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  • 11
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical crystallography 25 (1995), S. 223-226 
    ISSN: 1572-8854
    Keywords: Antifungal alkaloids ; 3-methylsampangine ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract 3-Methylsampangine, C16H10N2O, crystallizes in the monoclinic space group P21/c witha=7.260(3),b=10.697(5),c=15.342(6) Å, and β=102.69(4). All nonhydrogen atoms of this potent antifungal agent are planar to within 0.082 Å. The title compound exhibits potentin vitro antifungal activity againstC. neoformans, C. albicans andA. fumigatus.
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  • 12
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical crystallography 25 (1995), S. 295-298 
    ISSN: 1572-8854
    Keywords: Cage-diol ; crystal structure ; photooxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract An unusual photooxidation was noted upon photolytic cage closure of a substituted tricyclo[6.2.1.02.7]undecane-exo, exo-diol. The resultant compound, which may be regarded as a mono-reduced pentacyclo[5.4.0.02,6.03,10.05,9]undecane-8,11-dione, was characterizedvia X-ray crystallography. This species could be reduced to the tricyclo[6.2.1.02,7]undecane-endo, exo-diol under conditions previously shown to be inert for the parent dione.
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  • 13
    ISSN: 1572-8854
    Keywords: Benzonaphthodioxosuberane ; crystal structure ; radermachol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal and molecular structure of the title compound (2) C21H16O4 has been determined by an X-ray analysis, by direct methods from diffractometer data and refined by full-matrix least squares. The compound (2) crystallizes in the space group P21/a, with cell parameters:a=36.432(5),b=5.512(3),c=8.269(5) Å, β=108.0(3)°,z=4,D c =1.397 g/cm−3,R=7.8 for 1136 observed reflections. The conformation of the tetracyclic ring system shows a folding of two planar parts of the carbon skeleton about an axis passing thorough C8 and C16 of the seven membered ring C.
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  • 14
    Electronic Resource
    Electronic Resource
    Springer
    Structural chemistry 6 (1995), S. 57-63 
    ISSN: 1572-9001
    Keywords: Hydrogen bonding ; carcinogen ; polycyclic aromatic hydrocarbon derivative ; dihydrodiol ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The crystal structure of the weak carcinogen 5-methylchrysene-7,8-dihydro-7,8-trans-(e,e)-diol is reported. This molecule contains a distorted bay region as a result of the presence of the 5-methyl group as found in 5-methylchrysene and 5,6- and 5, 12-dimethylchrysene. One torsion angle in this bay region is 20
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  • 15
    ISSN: 1572-9001
    Keywords: MM3 ; PM3 ; MMX ; crystal structure ; norbonadienone ; distorted compound
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The reaction of 4,5-didehydroacenaphthene with phencyclone yields the title compound, a stable dibenzo-fused norbornadienone (8). The X-ray structure of8 is presented and compared with the structure predicted from a MM3, PM3, and a MMX calculation. Thermal decomposition of 8 produces, 7,16-diphenylcyclopenta[d,e]tribenzo[a,h,j]anthracene (9), a hydrocarbon that is computed to have a significantly twisted polycyclic aromatic skeleton with 19 kcal/mole of strain energy.
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  • 16
    Electronic Resource
    Electronic Resource
    Springer
    Journal of superconductivity 8 (1995), S. 595-598 
    ISSN: 1572-9605
    Keywords: (Ba/K)BiO3 ; lattice dynamics ; electron phonon coupling ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract The Lattice dynamics of Ba.6K.4BiO3 was investigated by inelastic neutron scattering on a superconducting single crystal (T c =26 K (midpoint)). At low frequencies the dispersion curves are very similar to those observed in BaPb.75Bi.25O3. Differences were found in the bond bending vibrations of the BiO6 octahedra which indicate that the binding in the K-doped compound is more ionic. Rather anomalous features were observed in the high frequency Bi-O bond stretching vibrations which resemble those observed in the high T c cuprates La1.85Sr.15CuO4 and YBa2Cu3O7. The observed frequency shifts are interpreted as the consequence from a strong electron phonon coupling. The data are compared to the results obtained on non superconducting Ba.98K.02BiO3.
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  • 17
    ISSN: 1573-904X
    Keywords: HMG-CoA reductase inhibitor ; SQ-33600 ; crystal structure ; hydrates ; solid-state fluorescence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract It has been shown previously that the disodium salt of a new HMG-CoA reductase inhibitor (SQ-33600) is capable of existing as a number of hydrate species [1]. Three crystalline solid hydrates and one liquid crystalline phase have been identified, each having a definite stability over a defined range of humidity. These forms have been found to exhibit varying fluorescence properties in their respective solid states, with differences in bandshapes and intensities being noted for each. These spectral variations have been correlated with the known pseudopolymorphism of the compound.
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  • 18
    Electronic Resource
    Electronic Resource
    Springer
    Pharmaceutical research 12 (1995), S. 337-341 
    ISSN: 1573-904X
    Keywords: 2-debenzoyl, 2-acetoxy paclitaxel ; docetaxel ; paclitaxel side-chain ; crystal structure ; solid state conformation ; intramolecular hydrogen bonding ; intermolecular hydrogen bonding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Crystals of the C2-acetate analog of paclitaxel, grown from a mixture of isopropyl alcohol and methanol, belong to the space group P2l with a = 9.058(3), b = 18.306(5), c = 15.043(1) Å, β = 97.09(1)°, Z = 2, V = 2475.1(9)Å3, D calc = 1.269 gcm−3 and µ = 0.75 cm−1. The structure was determined by direct methods and refined to R(F) = 0.054 and wR(F) = 0.057 for 605 variables and 3496 observed reflections. The paclitaxel side chain possesses a conformation similar to that observed in the crystal structure of docetaxel (Taxotere®). A three dimensional network of hydrogen bonds is formed through solvent molecules and stabilizes the crystal lattice.
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  • 19
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical crystallography 25 (1995), S. 765-768 
    ISSN: 1572-8854
    Keywords: Sesterterpene ; scalaran ; crystal structure ; marine compound
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The molecular geometry of a tetracyclic sesterterpene has been determined by X-ray diffraction. The conformation of the aldehyde group as observed in the crystal structure supports the rationalization for the absence of aldehyde proton coupling in the nmr spectra of the compound. Crystal data: C28H42O5, M.W.=458.6; orthorhombic, P212121;a=10.797(2),b=29.270(9),c=8.033(1)Å,V=2538.7Å3,Dx=1.199 g cm−3;R=0.045 for 2287 observed reflections.
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  • 20
    ISSN: 1572-8854
    Keywords: Tautomerism ; hydrogen bonding ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Crystals consisting of two distinct chemical entities, tautomers of each other, in exact 1∶1 ratio, have been obtained and their structure determined by X-ray analysis. The crystals of C9H11N3·C9H11N3 are monoclinic,P21/c,a=15.674(3),b=17.085(3),c=13.758(3)Å, β=90.78(2)°,Z=8. There are two hydroxylamine and two aminonitrone molecules in the asymmetric unit. Hydrogen bonds connect those molecules into chiral layers. Layers of opposite chirality alternate andthe crystal is centrosymmetric as a whole. Within those layers chains of tautomers joined by very strong O−H... O and strong N−H... N bonds can be recognized. Proton transfer along those chains with simultaneous rearrangement of π-bonds within the molecules would result in interconversion of tautomers and would affect chirality of the layer.
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  • 21
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical crystallography 25 (1995), S. 219-222 
    ISSN: 1572-8854
    Keywords: Calcium phosphate ; calcium pyrophosphate ; calcium potassium pyrophosphate ; crystal structure ; layer-type structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal structure of Ca10K4(P2O7)6·9H2O has been determined by single crystal X-ray diffraction. Crystals are hexagonal, space group P63cm witha=11.761(1),c=9.770(1) Å, andZ=1. The structure was refined toR=0.028 andR w=0.037 for 468 reflections withI≥3σ(I). The structure consists of a compact assembly of Ca and P2O7 ions arranged in layers perpendicular to thec-axis in a hexagonal array with relatively large open channels along thec-axis. The K ions and the water molecules are located in these open channels and are disordered.
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  • 22
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical crystallography 25 (1995), S. 463-467 
    ISSN: 1572-8854
    Keywords: 1,3-dithiole-4-carboxamides ; resonance effect ; short intramolecular S...O contact ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The two closely related compoundsN,N-dimethyl 5-(methylthio)-2-thioxo-1,3-dithiole-4-carboxamide1 andN-(p-methoxy-phenyl)-N-methyl 5-(methylthio)-2-thioxo-1,3-dithiole-4-carboxamide2 have been characterized by X-ray crystal structure determination. Crystal data for1: triclinic, $$P\bar 1$$ ,a=6.767(1),b=12.594(2),c=6.648(1) Å, α=101.38(1), β=93.37(2), γ=79.62(1)°,V=546.2 Å3,Z=2. Crystal data for2: monoclinic, Cc,a=19.836(4),b=6.057(1),c=15.860(3) Å, β=127.61(3)°,V=1509.5Å3,Z=4. The molecular structures of1 and2 show remarkable differences concerning the conformational behavior. These differences are related to the nature of the substituents at the nitrogen atom. The presence of an aromatic system in2 leads to an almost planar arrangement of the α-oxoketene dithioacetal moiety. This effect is accompanied by a short intramolecular S...O contact of 2.648(2) Å. In the absence of an aromatic system, as is the case for compound1, neither a resonance effect along the α-oxoketene dithioacetal fragment nor a short S...O distance is observed.
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  • 23
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical crystallography 25 (1995), S. 579-582 
    ISSN: 1572-8854
    Keywords: Dibenzo-18-crown-6 ; hetero bimetallic ; crown ether ; crystal structure ; ferric chloride
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Slow evaporation of a solution of ferric chloride and dibenzo-18-crown-6 in 3∶1 CH3CN∶CH3OH produced single crystals of the title complex. This heterobimetallic crown ether complex, [Na(dibenzo-18-crown-6)][FeCl4], crystallizes in the monoclinic space group P2t/n with cell parameters (at 22°C)a=14.608(6),b=10.466(9),c=17.276(9)Å, β=91.47(6)°, andD calc=1.46 g cm−3 for Z=4. The structure consists of discrete ions with the shortest Na ... Cl distance a lengthy contact of 3.56(1)Å. The average Na...O separation is 2.69(3)Å. The [FeCl4]− anion exhibits a distorted tetrahedral geometry with an average Fe−Cl bond length of 2.16(2)Å.
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  • 24
    ISSN: 1572-8862
    Keywords: Cluster carbonyl ; osmium ; gold ; arene ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Reduction of the heptaosmium cluster [Os7(CO)21] With [Et4N][NH4) gives the cluster dianion [Os7(CO)20]2−,1, in high yield. The reaction of the dianion with [AuPR 3Cl] (R=Et or Ph) in the presence of TlPF6 forms [Os7((CO)20(AuPR 3)2] [R=Et (2a);R = Ph(2b)] in 80% yield, while the corresponding reaction with (Os(C6H6)(CH3CN)3]2+ gives [Os8(CO)20 (η 6-C6H6)] (3) in reasonable yield (ca. 30%). The dianion,1, and the clusters2 and3 have been fully characterized by bout spectroscopic and crystallographic methods. The crystal structure of the [Ph4P]+ salt of1 shows that the metals in the anion adopt a capped octahedral geometry, with all twenty carbonyl ligands in terminal sites. The metal core geometry in2a is best described as a tricapped octahedron, and is based on the structure of the dianion1 with two adjacent octahedral faces capped by the Au atoms of the two AuPEt3 groups. In a similar fashion, the geometry of3 is related to that of1 with the addition of an Os(C6H6) unit capped to a triangular face, to give a bicapped octahedral framework.
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  • 25
    ISSN: 1572-8862
    Keywords: Undecaosmium carbido cluster ; µ-bridged chlorol preparation ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract A chloro-derivative of undecaosmium carbido cluster [Os11C(CO)27(µ-Cl)]-1 anion has been prepared and fully characterized by spectroscopic and crystallographic methods. The structure1 is an important intermediate for the conversion of [Os11C(CO)27]2 2 dianion to [OS10C(CO)24]2-3 dianion.
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  • 26
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    Journal of cluster science 6 (1995), S. 523-532 
    ISSN: 1572-8862
    Keywords: Molybdenum ; reduction ; seven-electron triangular cluster ; bridging sulfide ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The triangular six-electron cluster complex [Mo3S4Cl4(PEt3) x (thf)5] produced by the excision reaction of Mo3S7Cl4 with triethypholsphine is reduced by magnesium at − 20°C. Subsequent addition of dppe (=1,2-his(diphenylphosphino)ethane) to the reduced species affords a seven-electron triangular cluster complex [Mo3S4Cl3(dppe)2(PEt3)]. The complex crystallizes in the space groupCm witha=17.170(6),b-19.878(6),c = 13.289(5)β = 121.73(2)°,V = 3858(2) A3, andZ = 2. The structure shows an almost equilateral triangle of three molybdenum atoms capped by a Sulfur atom and bridged by three sulfur atoms. The Mo Mo distances, ranging from 2.804(1) to 2.809(1) A are elongated ca. 0.04 A as compared with lose of a six-electron cluster complex with drape ligands. Two molybdenum atoms have a chlorine and a dppe ligands, and the other molybdenum atom bas a chlorine and a triethylphosphine ligands. The UV-Vis spectrum has a characteristic broad hand centered at 1410 n m, which is not observed for six-electron clusters. The ESR spectrum indicates the presence of an unpaired electron consistent with the formulation of the compound as a seven-electron cluster.
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  • 27
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    Journal of inclusion phenomena and macrocyclic chemistry 22 (1995), S. 145-154 
    ISSN: 1573-1111
    Keywords: tert-Butylamine 7.25 H2O ; amine hydrate ; semi-clathrate ; clathrate hydrate ; hydrate ; hydrogen bonding ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Of the various hydrates oftert-butylamine, the title compound has been identified as the second-highest, melting incongruently at −19°C. Its crystal structure (orthorhombic, space groupPca21,Z=32 formula units per unit cell,a=24.80,b=16.440,c=25.29 Å) and the exact composition have been determined from X-ray diffraction at −150°C. The hydrate is a rather complex semi-clathrate, with the amine molecules not merely encaged, but also hydrogen-bonded, in a three-dimensional water host structure, which in turn is not fully four-connected. Nevertheless, it bears a clear relationship to the basic and genuine clathrate-hydrate cubic 12 Å type.
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  • 28
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    Journal of inclusion phenomena and macrocyclic chemistry 22 (1995), S. 211-219 
    ISSN: 1573-1111
    Keywords: (R, R)-Tartaric acid derivatives ; host-guest compounds ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract TheO, O′-dibenzoyl derivative of (R, R)-tartaric acid shows a good inclusion ability for diethyl and di-n-propol ethers. The two crystalline inclusion compounds have 1:1 stoichiometry and reveal isomorphous structures. Hydrogen bonded host molecules form chains running along thez axis of the unit cell and guest molecules join to these chains by short O−H...O hydrogen bonds. Hydrogen bonding in the crystals is characterized by a C(7)D first-order network. The ether molecules are in a fully extended conformation. They are accommodated in channel-like voids running along thex axis. Atomic displacement parameters are significantly larger for diethyl ether than for the di-n-propyl ether molecule reflecting less dense packing for this inclusion compound.
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  • 29
    ISSN: 1573-1111
    Keywords: Bridged calix[4]arene ; caesium complex ; ditopic receptor ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The crystal structures of two binuclear complexes between caesium and 1,3-calix[4]-bis-crowns have been determined. Cs2 Bis-benzoC6(NO3)2. 3CHCl3 (1) in whichBis-benzoC6 is 1,3-calix[4]-bis-benzo-crown-6, crystallizes in the orthorhombic system: space groupPca2 1 a=19.513(10),b=15.382(5),c=23.708(9) Å,V=7116(5) Å3,Z=4. Refinement led to a final conventionalR value of 0.065 for 2321 reflections. The structure of (1) is analogous to those already reported withBis-C6, (in whichBis-C6 is, 1,3-calix[4]-bis-crown-6) and NO 3 − as a counter-ion. Cs2 Bis-C6(NCS)2 (2) crystallizes in the monoclinic system: space, groupC2 a=36.57(2),b=11.47(1),c=13.65(1) Å, β=109.03(5)°.,V=5415(6) Å3,Z=4. Refinement led to a final conventionalR value of 0.063 for 2227 reflections. Compound (2) is made of dimers bridged by a disordered NCS− ion. The crown ether chain conformations are discussed.
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  • 30
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    Journal of inclusion phenomena and macrocyclic chemistry 22 (1995), S. 33-40 
    ISSN: 1573-1111
    Keywords: Calixarene-dye ; crystal structure ; inclusion compound
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The structure of thep-tetrakis-(4-nitrophenylazo)calix[4]arene-4-picoline (1∶4) complex has been determined by X-ray crystallography. Crystals are monoclinic, space groupC2/c,a=24.9097) Å,b=8.425(6) Å,c=33.81(1) Å, β=101.13(2)°,D c =1.330 g/cm3,Z=4, finalR value =0.067. The cone conformation adopted by this azocalixarene is disturbed by the positions of the picoline molecules. Two of them are inside the macorocycle cavity and the two others are outside.
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  • 31
    ISSN: 1573-1111
    Keywords: 18-crown-6 ; diaminofurazane ; crystal structure ; host-guest complexes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract An X-ray—diffraction study is reported for two molecular complexes containing 3,4-diamino-1,2,5-oxadiazole as guest (G) with 18-crown-6 (18-C-6) andcis-anti-cis-dicyclohexano-18-crown-6 (DCH-6B) as host. Both complexes are of the polymeric-chain structure with the guest molecule bridging two crown neighbours. ComplexI: [18-C-6*G*H2O], 1∶1∶1, monoclinic,P21/n,a=8.171(1),b=15.042(2),c=16.209(6) Å, β=101.15(2)°, finalR-factor 0.068. ComplexII: [DCH-6B*G], 1∶1, monoclinicC2/c,a=21.212(4),b=9.380(2),c=13.049(3) Å, β=108.61(3)°, finalR 0.047.
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  • 32
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    Journal of inclusion phenomena and macrocyclic chemistry 22 (1995), S. 119-130 
    ISSN: 1573-1111
    Keywords: Calixarene ; complexation ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A new method is described for the synthesis of isolatedp-tert-butyldihomooxacalix[4]arene (CALO) with a 24% yield. The ability of CALO to form complexes in the solid state with small neutral molecules has been studied; the potential guests were common solvents bearing various chemical functions. The powder obtained after evaporation of the solvent has been characterized by the X-ray powder diffraction technique. Analysis of the patterns shows the non-complexation of linear alkanes and alcohols, but formation of complexes when the guest is cyclic or when it bears an amine or a ketone function. As illustration of the possible arrangement of molecules in complexes, the structure of the 1:2 complex with tetrahydrofuran (THF) is presented: the crystals are monoclinic, space groupP21/c,a=9.459(2) Å,b=17.286(2) Å,c=30.469(6) Å, β=92.52(2)o,V=4977(2) Å3,Z=4,D c=1.099 Mg m−3, λ=1.54178 Å, μ=5.6 cm−1,R=0.086 for 3590 reflections withF〉4σ (F); one of the THF molecules is inside the cavity of the macrocycle, while the other, in the interhost space, exhibits disorder. In the CALO molecule, three out of the fourtert-butyl groups are disordered which may induce the disorder of the THF molecule.
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  • 33
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    Journal of inclusion phenomena and macrocyclic chemistry 22 (1995), S. 187-201 
    ISSN: 1573-1111
    Keywords: Inclusion compounds ; gossypol ; crystal structure ; hydrogen bonds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The crystal structure of the inclusion compound of gossypol withn-valeric acid as a guest molecule has been determined by X-ray structure analysis. The crystals of C30H30O8·(C5H10O2)2, are triclinic, space group $$P\bar 1$$ ,a=6.912(2),b=14.506(3),c=19.387(4) Å, α=78.85(2)°, β=83.92(3)°, γ=86.78(3)°V=1895(1) Å3,Z=2,D x=1.267 g cm−3, μ (CuK α)=0.768 mm−1,T=292 K. The structure has been solved by direct methods on intensity data collected for a twinned crystal and refined to the finalR value of 0.062 for 1606 observed reflections and 470 refined parameters. Gossypol-n-valeric acid (1/2) coordinato-clathrate is not isostructural with any of the previously investigated gossypol inclusion compounds but shows some structural similarities to gossypol-acetic acid (1/1). The host and one of the carboxylic acid molecules are connected via hydrogen bonds into molecular assemblies of a column type which are further bonded to centrosymmetric dimers of the secondn-valeric acid molecule. In effect, host and guest molecules are assembled into layer-type H-bonded aggregates. Structural features common to gossypol-n-valeric acid (1/2) and other earlier reported gossypol inclusion compounds are discussed.
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  • 34
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    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 7-13 
    ISSN: 0887-624X
    Keywords: radical terpolymerization ; charge transfer complexes ; phenanthrene ; maleic anhydride ; trans-stilbene ; thermal stability ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The radical terpolymerization of the donor-acceptor-donor monomer system, phenanthrene (P) - maleic anhydride (M) - trans-stilbene (S), was studied. These monomers are known to be nonhomopolymerizable. The terpolymerization was carried out in p-dioxane and/or toluene at 70°C in the presence of benzoyl peroxide used as the initiator. P and S were found to form charge transfer complexes (CTC) with M in p-dioxane at 35°C. The results obtained are discussed in terms of the free monomer and complex propagation models. It is shown that terpolymerization is carried out at a stage close to binary copolymerization of two complexomers. The reactivity ratio of P … M and S … M complexes was estimated by the Kelen-Tüdös method. Absorbance ratios at 1770 cm-1 (vC=0 of anhydride group), 764 cm-1 (δCH in monosubstituted benzene of S), and 820 cm-1 (δCH in disubstituted benzene of P) as a function of terpolymer composition were established. P - M - S terpolymers are shown to have high thermal stabilities. © 1995 John Wiley & Sons, Inc.
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  • 35
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    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 1375-1380 
    ISSN: 0887-624X
    Keywords: poly(vinyl chloride) ; electrical conductivity ; photodehydrochlorination ; laminated films ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Poly(vinyl chloride) (PVC) has been converted to an electrically conductive structure by combined electrochemical and photochemical methods. PVC was cast on a polypyrrole (PPy) film electrode which had been electrochemically prepared. The PVC layer in the laminated PVC/PPy films was first dehydrochlorinated under the illumination of UV light, and the generated polyenes were subsequently doped with I2 and FeCl3. The maximum electrical conductivity achieved for such PVC film was 2.51 X 10-2 and 8.63 10-2 S cm-1 after I2 and FeCl3 doping, respectively. The temperature dependence of the electrical conductivity showed different behavior in higher and lower temperature ranges. In the former (T 〉 243 K), the T-1 law held, and the activation energy and bandgap were estimated as 0.25 and 0.49 eV, respectively. In the latter (T 〈 243 K), the conductivity mechanism followed the variable range hopping model (T-1/4 law) in which the radius of the localized state wave function and the density of the localized states at the Fermi level were 1.25 × 103 Å and 1.03 X 1015 eV-1 cm-3, respectively. © 1995 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
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  • 36
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    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 1409-1417 
    ISSN: 0887-624X
    Keywords: emulsion polymerization ; oligomers ; polystyrene ; hydrotalcite ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The dominant species in the early stages of an emulsifier-free emulsion polymerization of styrene has been found to be an oligomer of two to three monomer units using a novel trapping technique. This involved the intercalation of charged primary oligomers between the layers of a hydrotalcite, [Mg4Al2(OH)12]2+[A]2- (where A = dianion). Hydrotalcites are an important class of lamellar, inorganic compounds whose interlayer spacing can be mod-ified by anion exchange. Our approach first involved preparing a hydrotalcite precursor in which the layers were propped apart by an organic dianion (terephthalate = TA). This material was then used to capture the negatively charged polystyrene oligomers from the emulsion polymerization reaction mixture. We found that TA was rapidly ion-exchanged for the charged oligomers.The resulting pillared hydrotalcite material was characterized using XRD and SEC. We found that the interlayer spacing between the hydroxide layers increased to 23.2 Å on exposure to the emulsion reaction mixture. This represents an interlayer expansion of 18.3 Å (after subtraction of the hydroxide layer contribution), which is cnsistent with intercalation of oligomers with two to three monomer units arranged in a bilayer. This size estimate was confirmed by the results of size exclusion chromatography. © 1995 John Wiley & Sons, Inc.
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  • 37
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    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 1455-1460 
    ISSN: 0887-624X
    Keywords: γ-oxidation ; polyethylene ; FTIR ; molecular weight ; elongation at break ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: γ-Oxidation of linear low-density polyethylene based on hexene and butene was investigated. Irradiation was performed at different dose rates in air (from 2 rad/s to 100 rad/s). Degraded samples were analyzed with IR combined with NO and SF4 derivatizations. Our results showed that the lower the dose rate, the higher the degree of oxidation in terms of γ-product formation. Ketone species appeared to be the dominant γ-products. The G values of γ-product formation were very dependent on the dose rate of initiation. Comparison of the G value ratio of different γ-products revealed stoechiometry differences. The complex appearance and disappearance of unsaturations was tentatively explained. The modifications of elongation at break induced by γ-irradiation were monitored by molecular changes in weight. This was not conclusive because changes in elongation at break are inconsistent with changes in Mw/Mn. © 1995 John Wiley & Sons, Inc.
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  • 38
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    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 1465-1474 
    ISSN: 0887-624X
    Keywords: grafting ; poly(styrene-graft-ethylene oxide) ; styrene-oxirane graft copolymers ; ethoxylation ; alkylation ; anionic polymerization of ethylene oxide ; poly(styrene-co-acryl-amide) ; crystallinity ; water absorption ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Poly(styrene-graft-ethylene oxide), having alkyl chains (C12 or C18) on the polystyrene main chain or on the poly(ethylene oxide) (PEO) side chains, were synthesized. The main chain was alkylated by first ionizing amide groups in a styrene/acrylamide copolymer with tert-butoxide, and then using the amide anions as sites for reactions with 1-bromoalkanes. An excess of amide anions was used in the reaction, and the remaining anions were subsequently utilized as initiator sites for the anionic polymerization of ethylene oxide (EO). Synthesis of poly(styrene-graft-ethylene oxide) with alkylated side chains was accomplished by polymerization of EO onto the ionized styrene/acrylamide copolymer, followed by an alkylation of the terminal alkoxide anions with 1-bromoalkanes. The alkylated graft copolymers were structurally characterized by using elemental analysis, 1H NMR, GPC, and IR spectroscopy. DSC analysis showed that only graft copolymers with PEO contents exceeding about 50 wt % and side chain crystallinities comparable to those of homo-PEO. Main chain alkylated graft copolymers generally had higher crystalinities, as compared to nonalkylated and side chain alkylated samples. The graft copolymers absorbed water corresponding to one water molecule per EO unit at low PEO contents. The water absorption increased progressively at PEO contents above 30 wt % for main chain alkylated samples and above 50 wt % for non-alkylated samples. © 1995 John Wiley & Sons, Inc.
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  • 39
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    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 1419-1429 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No Abstract
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  • 40
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    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 1447-1454 
    ISSN: 0887-624X
    Keywords: terpolymerization ; charge transfer complex ; allylglycidyl ether ; maleic anhydride ; methyl methacrylate ; thermo-crosslinking ; photo-crosslinking ; thermal degradation ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Radical copolymerization of donor-acceptor monomers, i.e., allylglycidyl ether (AGE), maleic anhydride (MA) and methyl methacrylate (MMA) are studied, where binary copolymerization of AGE...MA complex with MMA is obtained. Constants of charge transfer complex formation (Kc) and copolymerization (r1 and r2) are determined by 1H-NMR and Kelen-Tüdöş methods, respectively. It is found that synthesized film-forming terpolymers with free epoxy and anhydride groups on side chain of macro-molecules are being crosslinked easily under the effect of temperature and/or UV-ir-radiation. Observed crosslinking effect is proved by the DTA, TGA, and IR spectroscopic analyses. It is shown that complex-radical terpolymerization is very convenient method for the designing of reactive functional macromolecules of linear structure with self-crosslinking properties which can serve as a basis for the use in photolithographic applications. © 1995 John Wiley & Sons, Inc.
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  • 41
    ISSN: 0887-624X
    Keywords: saccharic acid ; dilactone ; polyaddition ; polyurethane ; diisocyanate ; deg-radation ; hydrolysis ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polyaddition of saccharic acid dilactones prepared from D-glucose and D-mannitol, D-glu-caro-, and D-mannaro-1,4:6,3-dilactones (1 and 2, respectively), with hexamethylene di-isocyanate (3a) and methyl (S)-2,6-diisocyanatocaproate (3b) was carried out by using dibutyltin dilaurate as a catalyst at 50, 25, and 0°C to give polyurethanes (4 and 5) having dilactone moieties in the main chains. The resulting polymers were found to decompose easily in phosphate buffers under neutral or slightly basic conditions (pH 7 or 8). Therefore, the polyurethanes may be used as novel degradable polymeric materials. © 1995 John Wiley & Sons, Inc.
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  • 42
    ISSN: 0887-624X
    Keywords: methacrylate bearing donor and acceptor moieties ; polymer effect ; intra-molecular charge-transfer interaction ; spacer length ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1-[3,5-Bis(N,N-dimethylamino)phenoxy]-ω-(2,4,6-tricyanophenylthio)alkanes (1a-c), where an electron-accepting 2,4,6-tricyanophenylthio group and an electron-donating 3,5-bis(N,N-dimethylamino)phenoxy one are linked with a spacer such as ethylene, trimethylene, and tetramethylene, were prepared in order to examine an effect of the spacer chain length on intramolecular charge-transfer interaction between the 2,4,6-tricyanophenylthio and 3,5-bis(N,N-dimethylamino)phenoxy groups. From the UV-vis spectra measurements of 1a-c, 1-[3,5-bis(N,N-dimethylamino)phenoxy]-3-(2,4,6-tricyanophenylthio)Propane (1b) carrying the trimethylene chain as a spacer was found to have the strongest intramolecular charge-transfer interaction. A new methacrylate-type monomer carrying the 1b unit as a side chain, 1-(2,4,6-tricyanophenylthio)-3-[3,5-bis(N,N-dimethylamino)phenoxy]-2-propyl methacrylate (2), was prepared successfully in 9.2% total yield in seven steps. The monomer 2 homopolymerized in benzene, tetrahydrofuran, acetone, and dimethyl sulfoxide in the presence of 2,2′-azobis(isobutyronitrile) at 60°C to give polymers [poly(2)] with molecular weights of 6,000 to 98,000. An intramolecular charge-transfer interaction in the poly(2) was found to be larger than that in the monomer 2 and to increase with an increase in the degree of polymerization of the poly(2), suggesting that there is an existence of polymer effect other than the polymer effect due to the high local concentration of the donor-acceptor pair. © 1995 John Wiley & Sons, Inc.
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  • 43
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    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 1511-1521 
    ISSN: 0887-624X
    Keywords: dispersion polymerization ; micron-size monodisperse polymer particles ; sty-rene ; butyl acrylate ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effect of the nitrogen purge, monomer purification, type of agitation, and presence of costabilizer on the particle size distribution (PSD) was investigated in the dispersion po-lymerization of styrene in ethanol and in the dispersion copolymerization of styrene and butyl acrylate in a water-ethanol mixture. Purging with nitrogen and, to a lesser extent, monomer purification, were of paramount importance to achieve monodispersity. The type of agitation had a week effect on the PSD, whereas the presence of costabilizer had no effect on the PSD. © 1995 John Wiley & Sons, Inc.
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  • 44
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    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 1581-1587 
    ISSN: 0887-624X
    Keywords: matrix polymerization ; polypyrrole ; chemical synthesis ; interpolymer complex ; water soluble polypyrrole ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The oxidative matrix polymerization of pyrrole (Py) by Ce(IV) in the presence of Polyacrylic acid (PAA) has been studied to obtain water-soluble and insoluble products. The role of the PAA, Pyrrole, and Ce(IV) concentration, order of component addition, the structure of polymer matrix (PAA, Hydroxy Ethyl Cellulose (HES), Poly-N-vinylpyrrolidone (PVP)], and model unit of PAA (propionic acid), on the polymerization system were investigated.Interaction of PAA with insoluble polypyrrole (PPy) and the interpolymer complex formation were investigated along with the aggregation of PPy onto the matrix polymer followed by spectral shifts. FTIR results of insoluble products obtained from the PAA-Py-Ce(IV) system and solubility of the system is explained in light of the mechanism of the polymerization of pyrrole on the polymer matrix. © 1995 John Wiley & Sons, Inc.
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  • 45
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    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 415-426 
    ISSN: 0887-624X
    Keywords: thermotropic ; liquid crystalline polymer ; nematic ; synthesis ; characterization ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of fully aromatic, thermotropic polyesters, derived from 3-phenyl-4,4′-biphenol (MPBP), nonlinear 4,4′-benzophenone dicarboxylic acid (4,4′-BDA), and various other comonomers was prepared by the melt polycondensation method and characterized for their thermotropic liquid crystalline behavior by a variety of experimental techniques. The homopolymer of MPBP with 4,4′-BDA had a fusion temperature (Tf) at 240°C, exhibited a nematic liquid crystalline phase, and had a narrow liquid crystalline range of 60°C. All of the copolyesters of MPBP with 4,4′-BDA and either 30 mol % 4-hydroxybenzoic acid (HBA), 6-hydroxy-2-naphthoic acid (HNA) or 50 mol % terephthalic acid (TA), 2,6-naphthale-nedicarboxylic acid (2,6-NDA) and low Tf values in the range of 210-230°C, exhibited a nematic phase, and had accessible isotropization transitions (Ti) in the range of 320-420°C, respectively. As expected, each of them had a broader range of liquid crystalline phase than the homopolymer. They had a “frozen” nematic, glassy order as determined with the wide-angle X-ray diffraction (WAXD) studies. The morphology of each of the “as-made” polyesters had a fibrous structure as determined with the scanning electron microscopy (SEM), which arises because of the liquid crystalline domains. Moreover, they had higher glass transition temperatures (Tg) in the range of 167-190°C than those of other liquid crystalline polyesters, and excellent thermal stabilities (Td) in the range of 500-533°C, respectively. © 1995 John Wiley & Sons, Inc.
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  • 46
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    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 1727-1733 
    ISSN: 0887-624X
    Keywords: polymerizing detergents ; monomer micelles ; radical polymerization ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Photo- and thermoinitiated radical polymerization of surface-active monomers with various structures was investigated in solution and in micelles in water. The relationship between kinetics and the structure of monomer associates was represented in the form of a universal curve. A model and kinetic description of polymerization in spherical micelles of monomer was proposed. The problem of micelle fixation by polymerization was solved. © 1995 John Wiley & Sons, Inc.
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  • 47
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    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 1745-1749 
    ISSN: 0887-624X
    Keywords: viologen polymer ; lyotropic ; critical concentration ; synthesis ; characterization ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: [no Abstrat]
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  • 48
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    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 1759-1765 
    ISSN: 0887-624X
    Keywords: compartmentalized ; seed ; emulsion ; oil-soluble initiators ; average radical number ; radical polymerization ; Kummer functions ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Expressions for calculating the stationary state distribution of radicals in compartmentalized systems with a constant number of reaction loci containing an oil-soluble initiator are given. Besides pairwise formation of radicals in the particles, desorption and reabsorption, water phase termination, solubility of the initiator in the aqueous phase, and the possibility of formation of a single radical species are taken into consideration. The calculation is based on a probabilistic analysis leading to a third-order recurrence relation solved using confluent, hypergeometric Kummer functions. Some calculated curves illustrating the de-pendence of the average number of radicals per particle on various relevant parameters are included. © 1995 John Wiley & Sons, Inc.
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  • 49
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    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 1807-1816 
    ISSN: 0887-624X
    Keywords: Oxetane ; oxirane ; photoinitiated cationic polymerization ; semiempirical molecular orbital calculation ; real-time FT-IR ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Photoinitiated cationic polymerization of oxetane, oxirane (epoxide), and a formulation of both was carried out and their reactivity compared. To investigate a formulated system of oxetane and oxirane in photoinitiated cationic polymerization, computational and experimental methods were used. In the computational study, we employed a semiempirical molecular orbital method (AM1). On the other hand, the reactivities of each system were evaluated and compared experimentally by a real-time FT-IR method. The computational study reveals that oxetane seems to polymerize in SN2 mechanism, but two possibilities, of SN1 mechanism through the α-cleavage and of SN2 mechanism through β-cleavage, are implied for oxirane. Using the real-time FT-IR method, the formulation of oxetane and oxirane was proved to possess rather high reactivities of oxetane toward photoinitiated cationic polymerization. The formulated system exhibited slightly lower number-average molecular weight than oxetane but higher than oxirane. These experimental observations are well explained in terms of the calculated reaction paths. © 1995 John Wiley & Sons, Inc.
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  • 50
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    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 1849-1857 
    ISSN: 0887-624X
    Keywords: emulsion polymerization ; acrylic polymers ; core shell ; supermicron ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The emulsion polymerization of large MMA/BA copolymer particles with narrow particle size distributions and core-shell structure is described. A series of sequential seeded growth emulsion polymerizations were used to obtain monodisperse particles with diameters of at least 3 μm, at 30% solids contents. Because the core and shell polymers used here were chemically similar, core-shell structures could not be verified by differential staining tech-niques. Core-shell structure was demonstrated by minimum film-forming temperature studies and by scanning electron microscopy in conjunction with energy dispersive x-ray analysis, using chlorine-labeled core polymers. © 1995 John Wiley & Sons, Inc.
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  • 51
    ISSN: 0887-624X
    Keywords: 2,4-ionene ; poly(quaternary ammonium)salt ; cobalt(II) phthalocyaninetetra-carboxylic acid ; cobalt(II) phthalocyanineoctacarboxylic acid ; mercaptoethanol ; autoxi-dation ; catalysis ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The promoting effects of 2,4-ionene on the cobalt(II) phthalocyaninetetracarboxylic acid-[CoPc(COOH)4] and cobalt(II) phthalocyanineoctacarboxylic acid-[CoPc(COOH)8] cata-lyzed autoxidation of 2-mercaptoethanol were studied. Dimerization of the CoPc(COOH)4 catalyst, combined with the disappearance of the catalytically inactive μ-peroxo complex and the appearance of substrate enrichment in the presence of 2,4-ionene, results in a 40-fold enhancement of the oxidation rate as compared with the polymer-free system. UV-VIS spectroscopy indicates that CoPc(COOH)8 is incapable of forming μ-peroxo complexes or 2,4-ionene-induced dimeric catalyst species under normal reaction conditions. Thus, it was possible to study exclusively the ionene-induced effect of substrate enrichment. Addition of 2,4-ionene to an aqueous CoPc(COOH)8 solution results in an activity enhancement by a factor of 2-3, which can be ascribed to substrate enrichment. Additionally, using mono-disperse ionene oligomers showed a molecular weight dependence of 2,4-ionene on the catalytic activity of CoPc(COOH)8, as was observed for the conventional 2,4-ionene/cobalt phthalocyaninetetrasodiumsulfonate system. The optimal polycation/catalyst ratios of both systems decrease with increasing chain length of 2,4-ionene, until a constant value is reached. This leads to the conclusion that the optimal polymer/catalyst ratios are predominantly determined by substrate enrichment. © 1995 John Wiley & Sons, Inc.
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  • 52
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    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 1873-1879 
    ISSN: 0887-624X
    Keywords: combined catalyst system ; polymerization ; polyphenylacetylene film ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The simultaneous polymerization and formation of polyphenylacetylene film by Nd(P204)3-Fe(AA)3-Al(i-Bu)3 catalyst system have been investigated. The combined catalytic effects between rare earth phosphonates with MT(naph)x or Fe(AA)3 systems are first proposed and compared. The polymerization features and kinetic behaviors with Nd(P204)3-Fe(AA)3-Al(i-Bu)3 system are described and discussed. The combined catalytic effects have the following order, respectively: Fe ≫ Co 〉 Cr 〉 Mn-Ni, Nd(P204)3-Nd(P507)3 〉 Nd(P350)3 and Tb 〉 Sm 〉 Yb 〉 Ho 〉 Lu 〉 Dy 〉 Nd-Er-Pr 〉 Y-Tm 〉 Ce 〉 Gd 〉 La. The overall polymerization activation energy was found to be 20.8 kJ/mol showing coordination-anionic polymerization characteristic. PPA films so obtained are very similar to the rare earth ones. © 1995 John Wiley & Sons, Inc.
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  • 53
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    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 1907-1912 
    ISSN: 0887-624X
    Keywords: substituted polyacetylene ; fluorine-containing polymer ; transition-metal catalyst ; gas permeability ; pervaporation ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis, properties, and membrane-separation functions of a novel fluorine-containing poly(phenylacetylene) were examined. The monomer used was [o-n-(perfluorohexyl)phe-nyl]acetylene, which has a rigid rod-like ortho-substituent. Polymers, whose intrinsic vis-cosities ([η]) were ca. 0.4-2.2 dL/g, were obtained in high yields with various W and Mo catalysts. The MoCl5-Ph3Sb catalyst achieved the highest [η] of 2.25 dL/g corresponding to an Mw over one million. The polymer was a brown solid soluble only in F -containing solvents such as m-(CF3)2C6H4. The oxygen permeability coefficient of the polymer mem-brane was 90 barrers, which is the second highest among those of ortho-substituted poly(phenylacetylenes). In the pervaporation of an ethanol-water mixture, the poly-mer membrane showed ethanol permselectivity [α(EtOH/H2O) = 1.7]. © 1995 John Wiley & Sons, Inc.
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  • 54
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    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 1921-1925 
    ISSN: 0887-624X
    Keywords: telechelic polymers ; living polymerization ; cationic polymerization ; vinyl ether ; aldehyde ; water ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
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  • 55
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    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 1979-1985 
    ISSN: 0887-624X
    Keywords: IPN ; zeolite ; polystyrene ; solid-state ; 13C-NMR ; SEM ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A hybrid inorganic/organic interpenetrating polymer network (IPN) of a three-dimensional network structure zeolite crystal (13X, powder) and crosslinked or linear polystyrene (PS) was prepared and characterized by differential scanning calorimetry (DSC), solid-state13C-NMR, and scanning electron microscopy (SEM). The size and shape of the crystalline zeolite particles were revealed on SEM micrographs in both the pure zeolite and the IPNs. Solubility tests and the results of DSC with solid-state 13C-NMR confirm that some organic PS chains are incorporated within the internal three-dimensional channels of the zeolite particles. We speculate that the internal PS chains may adopt an extended “one-dimensional” conformation and exhibit no bulk polymer glass transition. These novel hybrid inorganic/organic IPNs are a new kind of IPN structure. © 1995 John Wiley & Sons, Inc.
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  • 56
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    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 1969-1978 
    ISSN: 0887-624X
    Keywords: poly(methyl methacrylate) ; TMPD ; two-photon ionization ; main chain scission ; ESR ; GPC ; radical anion ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The main chain scission reaction of poly(methyl methacrylate) (PMMA) doped with N,N,N,′,N′-tetramethyl-p-phenylenediamine (TMPD) was examined by ESR spectroscopy and GPC measurement, and the scission mechanism was analyzed. The two-photon ionization of TMPD with excimer laser excitation at 77 K produced an ester radical anion of PMMA (PMMA·m̌), which becomes the main chain tertiary radical —CH2—C·(CH3)—CH2—after the detachment of the ester side group by annealing of the sample at room temperature. The main chain scission radical ·C(CH3)(COOCH3)—(PMMA·) which was produced by the β-scission from—CH2—·C(CH3)—CH2—showed the 13-line ESR spectrum instead of the ordinary 9-line, due to the fast quenching of the sample to 77 K. The change of the molecular weight distribution was measured by GPC after several irradiation-and-annealing operations. The simulation of the GPC curve confirmed that the scission re-action occurs at random in the PMMA chain in the solid and the main chain scission yield from the ester radical anion, [PMMA·]/[PMMA·m̌], is 0.30. © 1995 John Wiley & Sons, Inc.
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  • 57
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    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 2001-2011 
    ISSN: 0887-624X
    Keywords: surface modification ; aromatic polyamides ; oxygen plasma ; bond scission ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The surface of poly(p-phenylene terephthalamide) (PPTA) films was modified by oxygen plasma, and the modified film surface was analyzed by an advancing contact meter and X-ray photoelectron spectroscopy (XPS). The advancing contact measurement showed that the oxygen plasma treatment made the surface of the PPTA film hydrophilic. The XPS analyses also showed the increase in the O/C and N/C atom ratio, especially the O/C atom ratio, at the PPTA film surface by the oxygen plasma treatment. A main oxygen functionality formed by the oxygen plasma treatment is a carboxylic acid group, and a main nitrogen functionality formed is a protonated amino group. The formation of the oxygen and nitrogen functionalities formed by the oxygen plasma treatment is not restricted to the surface of the PPTA film, but penetrates at least 35 Å deep from the film surface. The formation of these carboxylic acid and protonated amino groups is a result of the bond scission of the amide linkages in the PPTA film. Interactions of photons in the oxygen plasma rather than interactions of electrons and activated oxygen atoms contribute greatly to the bond scission. © 1995 John Wiley & Sons, Inc.
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  • 58
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    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 2013-2025 
    ISSN: 0887-624X
    Keywords: vacuum ultraviolet oxidation ; polyethylene ; polypropylene ; plasma-polymer interaction ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The emission from low-pressure microwave plasmas in the vacuum-ultraviolet (VUV) region (λ 〈 200 nm) was investigated in order to use these plasmas as light sources for the study of the VUV photochemistry of polyethylene (PE) and polypropylene (PP) as part of the study of plasma-polymer interaction. These polymers, immersed in low-presure oxygen, were exposed to radiation with wavelengths down to 112 nm, the cut off of magnesium fluoride used as a window to separate the polymer specimen from the plasma light source. Total oxygen incorporation in the surface [O], and the formation of hydroxyl, carbonyl, and carboxyl groups were measured using XPS in combination with chemical derivatizations, particularly their dependence upon the radiation spectrum and the oxygen pressure around the sample. In most experiments the surface oxygen concentration [O] attained a constant value that appears to be related to the initial oxidation rate; this suggests a competition between oxygen incorporation and chain scission reactions, followed by the removal of volatile oxidation products. PE is usually oxidized to a higher level than PP, the latter appearing to be more susceptible to reaction with atomic oxygen than PE. A general initiation mechanism for the VUV experiments is proposed that allows us to explain the observed differences in behavior between PE and PP, and the results obtained under different irradiation conditions. The nature of oxidation products is in both cases very similar to what is observed after direct plasma treatment of the polymers. We conclude that short wavelength radiation contributes very appreciably to the observed surface modification effects during plasma treatment of PE and PP. © 1995 John Wiley & Sons, Inc.
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  • 59
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    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 2057-2067 
    ISSN: 0887-624X
    Keywords: methacrylate monomers ; polymerization kinetics ; stereostructure ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of unsaturated monomers containing one or more hydroxyl groups by reaction between polyalcohols (number of OH, n≥2) and monoacid chlorides has been theoretically analyzed. The difficulties were shown involved in the preparation of these monomers with a high degree of purity even in the most favorable case of the completely substituted compound. The calculated mole fractions of the two monomers that can be obtained by reaction between neopentylglycol and methacryloyl chloride were compared with the experimental ones. Kinetic experiments of the polymerization of 3-hydroxyneopentyl methacrylate and 2-hydroxyethyl methacrylate were carried out at different temperatures in 1,4-dioxane for the former monomer and dioxane and absolute ethanol for the latter. Dilatometric techniques and nonlinear least-squares methods were used to obtain kinetic data and to determine the kinetic constants, respectively. In homogeneous solution the values of kp/k1/2t for the 3-hydroxyneopentyl methacrylate and 2-hydroxyethyl methacrylate was determined by 13C-NMR spectroscopy and the molar fractions of tactic triads and dyads were calculated from different resonance signals. The polymers are predominantly syndiotactic and follow a Bernoullian distribution of tactic sequences. Finally, the glass transition temperatures of both polymers, determined calorimetrically, were 145 and 89°C, respectively. © 1995 John Wiley & Sons, Inc.
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  • 60
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    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 1917-1920 
    ISSN: 0887-624X
    Keywords: poly(amide-imide-sulfonamide)s ; unsymmetrical diamino monomers ; Yamazaki reaction ; triphenylphosphite ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 61
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    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 1935-1940 
    ISSN: 0887-624X
    Keywords: solketal ; monocarbamate diol ; polyurethane ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 62
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    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 1941-1942 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 63
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    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 1957-1967 
    ISSN: 0887-624X
    Keywords: end-capping reactions ; oligo(styryl)lithium anions ; gas chromatography ; mass spectrometry ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Anionic living polymerization methods, using organometallic initiators such as butyllithium reagents, have proven useful for, inter alia, styrene polymerization and are amenable to subsequent functionalization of poly(styryl)lithium in the termination step. In this study, general methods for the selective preparation of small styrene oligomers and termination of the intermediate oligo(styryl)lithium anions were investigated. The crude reaction mixtures were analyzed directly by tandem gas chromatography/mass spectrometry (GC/MS). Of the carbon- and silicon-based electrophiles tested, chloro(chloroalkyl)silanes, Cl-SiR2(CH2)nCl in particular, were shown by GC/MS to be regioselective end-capping reagents, thus allowing subsequent transformation to the primary amine. The combined GC/MS data allow not only an estimate of the degree of functionalization, but also the identification of by-products, thus providing insight into the end-capping process that otherwise might be difficult to access. © 1995 John Wiley & Sons, Inc.
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  • 64
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    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 1987-1994 
    ISSN: 0887-624X
    Keywords: aromatic polyamides ; polyisophthalalamides ; pendent oligomeric benzamide groups ; 5-(4-benzoylamino-1-benzoylamino)isophthalic acid ; water uptake ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of polyisophthalamides having pendent oligomeric benzamide groups were prepared by the Yamazaki reaction from common aromatic diamines and 5-(4-benzoylamino-1-benzoylamino)isophthalic acid. The latter was synthesized from 5-aminoisophthalic acid in a three-step synthesis by successive incorporation of benzamido groups. The new polymers were characterized by NMR, DSC, TGA, and WAXD and the properties were compared to those of corresponding unsubstituted polyisophthalamides. All of the polymers were essentially amorphous and their Tgs were about 20°C higher than the reference polymers. Initial thermal decomposition temperatures ranged from 375 to 420°C. All of the polymers were soluble in aprotic polar solvents without added salts. Properties of particular note were: the water uptake, which was particularly high, ranging from 7.5 to 18.2%, and the temporary insolubilization in concentrated sulfuric acid of films of the polymers heated for a short time to ≥ 200°C. © 1995 John Wiley & Sons, Inc.
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  • 65
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    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 2049-2055 
    ISSN: 0887-624X
    Keywords: graft polymerization ; grafting rate ; electron beam irradiation ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: LLDPE film pre-irradiated by electron beam (EB) in air and argon was grafted in an aqueous acrylamide solution containing Mohr's salt in the concentration range 0.0025-2% The grafting rate and yield were strongly dependent on the Mohr's salt concentration, mainly as a result of chain termination. The exponential grafting rate dependence on the pre-irradiation dose was quite insensitive to a hundred-fold variation in Mohr's salt concentration. © 1995 John Wiley & Sons, Inc.
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  • 66
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    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 2157-2163 
    ISSN: 0887-624X
    Keywords: reactive polyester ; pendant carboxyl group ; chemoselective polycondensation ; polymer catalyst ; polymer reaction ; bifunctional catalytic mechanism ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Aromatic polyester, copolyester, and poly(ester-amide-thioester) having pendant carboxyl groups are directly synthesized by the organic phase/water phase interfacial polyconden-sation using low-molecular and polymeric phase transfer catalysts. Spectral analysis of the resulting polymers indicates that the nucleophilicity of salts of phenols to diacid chloride is far higher than that of salts of carboxylic acids and chemoselective esterification occurs in a 100% yield. Even if the polymeric catalyst having amino acid moiety as a nucleophilic group is used in the polycondensation, the polymers do not contain anhydride groups. The polyester can be almost quantitatively converted to polymers with different reactive groups by reacting the pendant carboxyl groups with alkyl halides in a DMAc-H2O mixture con-taining K2CO3. A bifunctional catalytic mechanism is proposed for the chemical modification of the polyesters. © 1995 John Wiley & Sons, Inc.
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    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 2175-2182 
    ISSN: 0887-624X
    Keywords: gadolinium tricarboxylate ; copolymerization of butadiene and styrene ; effect of pKa of ligand ; diad analysis ; cis polymerization mechanism ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Homo- and copolymerizations of butadiene (BD) and styrene (St) were carried out by gadolinium catalysts having various tricarboxylate ligands [Gd(OCOR)3: R = CH3, CH2Cl, CHCl2, CCl3, and CF3], to investigate the effects of ligands and discuss the cis polymerization mechanism. Polymerization of BD with Gd(OCOR)3 - (i - Bu)3Al - Et2AlCl catalysts was carried out in hexane at 50°C. By each catalyst, poly(BD) having a high cis content (cis = 97-99%) in 22-85% yields for 2-24 h were obtained. The ligands with low pKa values increased the polymerization activity as follows: R of Gd(OCOR)3: CF3 〉 CCl3 〉 CHCl2 〉 CH2Cl ∼ CH3. On the other hand, in the polymerization of St or copolymerization of BD and St under similar conditions, the highest activity was attained by a Gd(OCOCCI3)3- based catalyst. The difference in the optimum ligand among the homo- and copolymerization of BD and St was discussed on the basis of energy levels of the catalysts. In the copolymers of BD and St, the cis-1,4 content of the BD unit decreased with increasing St content. Furthermore, according to the diad analysis of copolymers (St content ∼ 14.5 mol %) by 13C NMR spectroscopy, the low cis value of the BD unit was observed in the St-BD diad (cis/trans/vinyl = 24/53/23), while the high cis value of the BD unit remained in the BD-BD diad (cis/trans/vinyl = 89/10/1). These results suggest that the terminal BD unit is controlled by the cis configuration by the coordination between the penultimate cis vinylene unit and the gadolinium metal catalyst, whereas the presence of the penultimate St unit interferes with cis polymerization of the terminal BD unit. The difference in the coordination mechanism in the course of polymerization between rare earth metal and transition metal catalysts such as the Ni(acac)2 and Co(acac)3-based catalyst was also discussed. © 1995 John Wiley & Sons, Inc.
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  • 68
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    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 2193-2201 
    ISSN: 0887-624X
    Keywords: ring-opening polymerization ; poly(trimethylene carbonate) ; butyltin tri-chloride ; cationic mechanism ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Numerous BuSnCl-3, Bu2SnCl-2, and Bu3SnCl-initiated polymerizations of cyclo(tri-methylene carbonate) (TMC) were conducted in bulk. In addition to the initiator, reaction time, temperature, and monomer/initiator (M/I) ratio were varied. Yields above 90% were obtained with all three initiators, but their reactivities decrease in the order BuSnCl3 〉 Bu2SnCl2 〉 Bu3SnCl. The maximum molecular weights decrease in the same order. With BuSnCl3 Mws up to 250,000 were obtained. These molecular weights were determined by GPC on the basis of the universal calibration method. In this connection Mark-Houwink equations for two solvents, tetrahydrofuran (THF) and CH2Cl2 were determined and compared with literature data. Furthermore, mechanistic aspects were studied. 1H- and 13C- NMR spectra revealed that BuSnCl3 forms complexes with the CO-group of TMC, whereas Bu2SnCl3 do not cause NMR spectroscopic effects. Kinetic studies in chloroform and nitrobenzene and a comparison with Bu3SnOMe suggest that at least BuSnCl3 initiates a cationic mechanism. However, in contrast to SnCl4 (or SnBr4), BuSnCl3 does not cause decarboxylation. Regardless of the initiator 1H-NMR spectroscopy revealed CH2OH and CH2CI endgroups in all cases. © 1995 John Wiley & Sons, Inc.
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    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 2241-2250 
    ISSN: 0887-624X
    Keywords: poly(amide-imide)s ; trimellitic acid ; smectic-A phase ; phase transition ; synchrotron radiation ; bâttonet texture ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polycondensation of α, ω-bis(-4-aminophenoxy) alkanes with trimellitic anhydride chloride (TMA-Cl) in m-cresol yielded a new class of poly(amideimide)s. Starting from the same diamine spacers poly(amideimides) with a more regular sequence of amide and imide groups were prepared by another synthetic method. All these poly(amide-imide)s are semi-crystalline and melt in the range of 250-300°C. They form a smectic-A phase over a narrow temperature range and suffer thermal degradation at the isotropization temperature (330-350°C). The smectic-A phase was characterized by optical microscopy (“batonnet texture”) and by synchrotron radiation measurements conducted at a heating rate of 20°C. Furthermore, it is demonstrated that slight variation of the chemical structure, such as methyl substituents or meta positions in the spacer prevent the formation of a LC phase. © 1995 John Wiley & Sons, Inc.
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    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 621-627 
    ISSN: 0887-624X
    Keywords: phenolic-triazine ; cyanate ester ; phenol formaldehyde resin ; cardanol ; cyclotrimerization ; matrix resin ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cardanol incorporated-phenol-formaldehyde novolac resins were synthesized by acid and base catalyzed reactions. The novolacs were transformed to their cyanate esters. The thermal cure characteristics of the cyanate esters depended upon the composition. The presence of cardanol proportionately facilitated the curing. The thermal characterization of the novolacs and the corresponding cured phenolic-triazine networks indicated a dedicated a detremental effect of cardanol on the thermal stability and char residue of the resins. © 1995 John Wiley & Sons, Inc.
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    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 633-642 
    ISSN: 0887-624X
    Keywords: free radicals ; grafting ; kinetics ; methacrylate ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of grafting a basic monomer, 2-(dimethylamino)-ethyl methacrylate (DMAEMA) to hydrocarbon substrates have been investigated. These systems were chosen as models for the grafting of a homopolymerizable monomer to polyolefins such as polyethylene. The reactions with squalane and n-eicosane were initiated by an organic peroxide, 2,5-dimethyl 2,5 dit-butylperoxy)-3-hexyne; grafting yields become significant at high reaction temperatures and low monomer concentrations. In squalane, the order of reaction with respect to monomer increased from about 1.1 for 0.22-0.44M DMAEMA to almost 2 at 0.69M DMAEMA; the order with respect to initiator was 0.56. The overall activation energy in the 130-160°C temperature range was, however, surprisingly low, 42±5 kJ mol-1. When analytical data were used to separate the overall rate into those for grafting and homopolymerization, different kinetic paths were observed for the competing reactions. These results are interpreted in terms of two different mechanisms; intramolecular chain transfer plays an important role in grafting, while depropagation becomes a major factor in homopolymerization at temperatures above 150°C. © 1995 John Wiley & Sons, Inc.
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    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 653-663 
    ISSN: 0887-624X
    Keywords: photopolymerization ; poly(indanes) ; cationic polymerization ; photopolymerizable poly(imide)s ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of a series of monomers containing isopropenylphenoxy groups was carried out. On irradiation with UV light in the presence of onium salt photoacid generators, these monomers undergo a chain extension reaction consisting of a dimerization followed by a Friedel-Crafts ring closure which results in the formation of polymers with indane groups in the backbone. Aryl imide-containing monomers bearing isopropenylphenoxy groups were also shown to undergo facile photoinduced cationic polymerization. The resulting polymers displayed excellent thermal stability. © 1995 John Wiley & Sons, Inc.
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    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 2339-2345 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The state of p-phenylphenol molecules in dioxane/water mixture, a commonly used reaction system for enzymatic polymerization of phenols and aromatic amines, was investigated by difference UV absorption spectroscopy and Fourier transform (FT) Raman spectroscopy. The aggregate of p-phenylphenols is found on the basis of the exciton peaks observed in difference UV absorption spectra. FT Raman spectroscopy demonstrates further that p-phenylphenol molecules aggregate together in “face to face” fashion. A simplified model is proposed for aggregation of p-phenylphenol molecules in dioxane/water mixture, which can elucidate the variation of the molecular weight of poly (p-phenylphenol) coupled in the reaction system. © 1995 John Wiley & Sons, Inc.
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  • 74
    ISSN: 0887-624X
    Keywords: soluble ethynylene-containing polyamides ; palladium-catalyzed polyconden-sation ; ethynylene-bearing amide monomers ; thermal behavior ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: New ethynylene-containing aromatic polymides were synthesized by the carbon-carbon crosscoupling polycondensation of aromatic diiodides with aromatic amide-bearing diethynyl compounds in the presence of a palladium catalyst, cuprous iodide, and an organic base. The polymers having sulfone linkages were soluble in various organic solvents and their weight average molecular weights were in the range of 12,500 and 26,500. The polymers with the highest inherent viscosity were obtained, when the monomer ratio of a diethynyl compound to a diiodide was 1.01. The polymers showed no detectable glass transition temperature and no weight loss up to around 300° C in nitrogen. The thermal crosslinking of the polymers occurred at 280°C through the existing internal ethynylene group. © 1995 John Wiley & Sons, Inc.
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    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 2393-2402 
    ISSN: 0887-624X
    Keywords: metallocene, supported ; polypropylene, isotatic ; propylene polymerization, kinetics of, modelling of ; polyolefins, particle growth model for ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Several propylene polymerizations are carried out with supported metallocene catalyst, prepared by reaction of silica gel with methylaluminoxane and then with rac-dimethylsi-lanediylbis(indenyl)zirconiumdichloride. The rate-time curves obtained are analyzed to understand the influence of support and triisobutylaluminium on the reaction. As a first attempt to model this system we developed a partially new praticle growth model, based on a shell by shell fragmentation hypothesis (gradual break-up from the outside to the inside of the particle), and a final multigrain structure of the particle. A kinetic scheme including the TIBA interaction with the supported catalyst is also presented. The model prediction and the experimental data are compared for the rate-time curves and polymer properties. © 1995 John Wiley & Sons, Inc.
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  • 76
    ISSN: 0887-624X
    Keywords: 3-fluoro-4′-(11-vinyloxyalkoxy)-4-biphenyl (2R,3S)-2-fluoro-3-methylpen-tanoate ; “living” cationic polymerization ; liquid crystallinity ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis and “living” cationic polymerization of 3-fluoro-4′-(11-vinyloxyundecany-loxy)-4-biphenylyl (2R,3S)-2-fluoro-3-methylpentanoate (12-11) and 3-fluoro-4′-(8-vi-nyloxyoctyloxy)-4-biphenylyl (2R,3S)-2-fluoro-3-methylpentanoate (12-8) are presented. Poly (12-11)s and poly (12-8)s with degrees of polymerization from 4.0 to 16.5 and poly-dispersities ≤ 1.13 have been synthesized and characterized by differential scanning cal-orimetry (DSC) and thermal optical polarized microscopy. Over the entire range of molecular weights poly (12-11)s and poly (12-8)s exhibit an enantiotropic SA and an unidentified SX phase. In addition, regardless of its molecular weight, poly (12-8) exhibits a S*c phase in between the SA and Sx phases. Poly (12-11) and poly (12-8) show lower transition tem-peratures and broader temperature ranges of all their mesophases as compared to the corresponding polymers without a fluorine atom on the biphenyl group. The role of the connecting group between the biphenyl and chiral group of the mesogenic unit on the phase behavior of these polymers is also discussed. Copolymers of 12-8 with (2R,3S)-2-fluoro-3-methylpentyl 4′-(11-vinyloxyundecanyloxy)biphenyl-4-carboxylate (13-11) {i.e., poly-[(12-8)-co-(13-11)] (X/Y), where X/Y represents the molar ratio of monomer 12-8 to monomer 13-11} with DP of ca. 11 and polydispersities lower than 1.23 were also syn-thesized and characterized. Their SA and S*c mesophases exhibit continuous dependences of composition and this support the assignment of the mesophases exhibited by poly (12-8). © 1995 John Wiley & Sons, Inc.
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    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 2415-2423 
    ISSN: 0887-624X
    Keywords: photoinitiated cationic polymerization ; 1-propenyl ethers ; siloxanes ; 1-pro-penyl ether-functionalized siloxanes ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of 1-propenyl ether-functionalized siloxanes (PFS) has been achieved by the controlled, rhodium-catalyzed, chemoselective hydrosilation of 1-allyloxy-4(1-propen-oxy) butane with various H-functional siloxanes. It was shown that the hydrosilation pro-ceeds exclusively at the allyl ether group of 1-allyloxy-4(1-propenoxy) butane without par-ticipation at the 1-propenyl ether group. The photoinduced cationic polymerization of these monomers was studied using various analytical techniques and found to take place very rapidly. © 1995 John Wiley & Sons, Inc.
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    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 2443-2447 
    ISSN: 0887-624X
    Keywords: polyaniline ; oxalic acid dopant ; EPR ; IR ; UV/V ; TGA ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polyaniline-oxalic acid salts were prepared at 5 and 30°C by chemical polymerization of aniline using different concentration of oxalic acid. Polyaniline base was obtained from the corresponding polyaniline salt by dedoping using aqueous ammonium hydroxide solution. Conductivity measurements, elemental analysis, Infrared, electronic absorption, electron paramagnetic resonance spectral, and thermogravimetric analysis were performed on the polyaniline salts and bases. Composition and the extent of dopant in polyaniline salt systems where determined. The value of composition of polyaniline: oxalic acid is 4: 1.6 and the polymer yield is around 66%. The value of conductivity, polymer yield and composition of polyaniline-oxalic acid salt is independent of concentration of oxalic acid used and also the synthesis temperature. The results are compared with polyaniline-hydrochloride salt prepared by chemical polymerization. The conductivity of polyaniline-oxalic acid salt is three orders of magnitude lower than that of polyaniline-hydrocholoride salt. © 1995 John Wiley & Sons, Inc.
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  • 79
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    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 2435-2441 
    ISSN: 0887-624X
    Keywords: poly(o-phenylenediamine) ; solubility ; conducting polymer ; molecular structure ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A conducting polymer, poly(o-phenylenediamine) (PoPD), has been obtained as stable film onto an electrode surface by the electropolymerization of o-phenylenediamine in 0.1 mol dm-3 H2SO4. The film thickness did not exceed 0.85 μm because of its low electrical con-ductivity. The virgin “doped” polymer film was soluble in dimethylsulfoxide N, N-dimeth-ylformamide, acetone, and tetrahydrofuran without any pretreatment. The highest solubility obtained was 17 g dm-3 in dimethylsufoxide. A cast film of PoPD on a substrate was prepared from its dimethylsulfoxide solution. The mean molecular weight of PoPD was found to be 11,000 with the gel permeation chromatography. The STM observation exhibited that the cast film was considerably uniform compared to the electrodeposited film. The cyclic voltammogram of such film showed a reversible redox property accompanied with excellent electrochromism between transparent yellow and brown. It was suggested from the 1H-FTNMR and FTIR spectra and the elemental analysis that the polymeric backbone has 1, 4-substituted benezenoid-quinoid structure. © 1995 John Wiley & Sons, Inc.
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  • 80
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    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 2463-2471 
    ISSN: 0887-624X
    Keywords: cycloaliphatic epoxides ; mechanistic studies ; photoinitiated cationic poly-merization ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of a series of difunctional epoxides bearing two epoxycyclohexyl groups linked together by an alkylene ether group has been carried out. Subsequently, the reactivities of these novel monomers was investigated and compared to the reactivity of the cycloali-phatic epoxide, 3,4-epoxycyclohexylmethyl 3′,4′-epoxycyclohexane carboxylate (I) in pho-toinitiated cationic polymerization. It was observed that alkylene oxide linking the two epoxycyclohexyl groups was short and the monomers are more reactive than I. The effects of the photoinitiator structure and the experimental conditions of the cationic photopo-lymerization on the rates was also studied using real-time infrared spectroscopy. © 1995 John Wiley & Sons, Inc.
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    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 2515-2519 
    ISSN: 0887-624X
    Keywords: thymine styrene monomer ; functional styrene monomer ; multifunctional monomer ; photoresist ; photocrosslinking ; photopolymer ; 2π + 2π photocyclization ; 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 33 (1995), S. 2505-2513 
    ISSN: 0887-624X
    Keywords: neodymium ; polybutadiene ; alkylaluminum ; alkylaluminum chloride ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The ternary neodymium-based catalyst for the polymerization of 1,3-butadiene, Nd(versatate)3/Ali-Bu2H/tert-butyl chloride, has been examined with respect to the effects of a range of alkylaluminums and alkylaluminum chlorides. Using either pre-formed or in situ catalysts, observations pertaining to catalyst activity and physical state and the characteristics of the final polymer are discussed. The catalyst activity series with the type of alkylaluminum was found to be: Aln-Pr3 ≫ Aln-Dodec3 = Aln-Oct3 = Aln-Hex3 〉 Ali-Bu2H 〉 Ali-Bu3 〉 AlEt3 ≫ AIMe3. Polybutadiene cis content was found to vary with the type of alkylaluminum used. Pre-formed catalysts using methylaluminum chlorides as chloride source were found to be the most active; AlMe2Cl chloride gave the highest activity. The activity of in situ catalysts prepared using alkylaluminum chlorides was found to be independent of alkylaluminum chloride structure. Polybutadiene prepared using catalysts based on different alkylaluminums and alkylaluminum chlorides was found to decrease in cis content with conversion. © 1995 John Wiley & Sons, Inc.
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    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 2521-2522 
    ISSN: 0887-624X
    Keywords: gelatin ; sol-gel transition ; metal ions ; viscosity ; radiation ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 84
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    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 2533-2549 
    ISSN: 0887-624X
    Keywords: free radical ; grafting ; kinetics ; model ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Graft site initiation occurs by primary radical and/ or polymeric radical attack on the back-bone polymer. The controlling mechanism is determined by the structure of the backbone and the activity of the free radicals. The efficiency of incorporating monomer into the graft chains depends upon the graft site initiation mechanism and the mode of polymer chain termination (recombination or disproportionation). A kinetic analysis results a series of uniquely different expressions describing the graft efficiency, φ corresponding to different combinations of graft site initiation and chain termination mechanisms. The dependency of φ upon monomer, initiator, and backbone concentrations is different from case to case. The complete kinetic model is capable of predicting reaction rate, graft efficiency, graft frequency, graft ratio, and molecular weight averages and distributions. Simulations are provided to compare predicted results with experimental data for two different systems which show contrasting mechanisms of graft site initiation and mode of termination. © 1995 John Wiley & Sons, Inc.
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    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 2613-2621 
    ISSN: 0887-624X
    Keywords: solution conformation ; amphoteric copolymer ; 14N-NMR ; 23 Na-NMR ; poly-electrolyte ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Solution conformations and dynamic mobilities of novel amphoteric copolymers were studied for aqueous solutions of p(sodium 2-methacryloxyethanesulfonate-co-2-methacryloy-loxyethyltrimethylammonium iodide) [P(NaMES-co-METMAI)] as a function of com-position, concentration, and addition of HCI or KCI. As HCI or KCI was added successively to 5 w/v% copolymer solutions, the reduced viscosities of the solutions were reduced except the 1:1 copolymer solution. The dynamic mobility of the cationic side chain was estimated with the quadrupolar 14N-NMR relaxation technique. The motion of the interacting coun-terion, Na+, was studied by Poisson-Boltzmann electrostatic theories and the quadrupolar 23Na-NMR. Since the intramolecular 1:1 ion pair between MES- and METMA+ acts as an effective charge-screening factor, the copolymers P(NaMES-co-METMAI) behave as ordinary polyelectrolytes with the exception of the 1 : 1 copolymer. © 1995 John Wiley & Sons, Inc.
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    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 2605-2612 
    ISSN: 0887-624X
    Keywords: complex formation ; PEO ; copolymer ; phenolic resin ; hydrogen bonding ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Comb copolymers formed from acrylamide and poly(ethylene-glycol) methacrylate macro-monomer (PAM-co-PEG) were compared to poly(ethylene oxide) (PEO) with respect to hydrogen bond complex formation with water-borne phenolic resins. The behaviors of the two types of high molecular weight polyethers were similar. Complex formation gave a transient increase in viscosity followed by precipitation. Copolymers with pendant PEG chain lengths ≥ 9 formed complexes with phenolic resin whereas PEG homopolymer with a molecular weight of 2000 did not form a complex. For both copolymer and high molecular weight PEO, the tendency of the complex to precipitate increased when the pH was decreased from 7 to 4. Acridine orange, a cationic dye, bound to the phenolic resin and, after the addition of PEO, yielded visible complex gels with diameters about 20 μm. © 1995 John Wiley & Sons, Inc.
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    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 2657-2665 
    ISSN: 0887-624X
    Keywords: amphiphilic rubber ; butyl rubber ; saccharide ; microphase-separated structure ; thermoplastic elastomer ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new type of amphiphilic elastomer was synthesized, which consisted of butyl rubber and a D-maltose derivative as a backbone and side groups, respectively. The synthesis was accomplished by the sequence of the three following reactions: (1) Hydroxyl groups of D-maltonolactone were protected by a trimethylsilyl group. (2) The resulting maltonolactone derivative was subjected to a reaction with chemically modified butyl rubber having pendant amino groups. (3) The protecting trimethylsilyl groups on the maltose residues were removed by treating with tetra-n-butylammonium fluoride. This new amphiphilic elastomer behaved as a thermoplastic elastomer and showed good mechanical properties. The saccharide seg-ments aggregated in the hydrophobic butyl rubber matrix to form a microphase-separated structure, as confirmed by differential scanning calorimetry, transmission electron mi-croscopy, small-angle x-ray scattering, and dynamic mechanical measurements. The ag-gregated saccharide domains are estimated to function both as crosslinking sites and rein-forcing fillers in the rubber matrix. © 1995 John Wiley & Sons, Inc.
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    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 2673-2680 
    ISSN: 0887-624X
    Keywords: main chain LCPs ; ionic LCPs ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An ionogenic main chain liquid crystalline polymer was synthesized. In contrast to previous studies the charged sites were incorporated into the flexible spacer and not into the mesogenic group. This was done through quaternization of 1,2-bis(4-pyridylethane) with a biphenyl-4,4′-nonanoxytoluenesulphonate. The polymer displayed thermotropic and lyotropic me-sophases. The thermotropic mesophase was smectic. Organic counterions such as meth-ylsulfonates and p-toluenesulfonates were found to be favorable to the development of mesophases, due to the increased solubility and lower isotropisation temperatures, when compared to bromide counterion containing polymers. Easy supercooling, dependence on thermal history, and the development of batonnet textures on cooling from the melt were also observed. © 1995 John Wiley & Sons, Inc.
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  • 89
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    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 2705-2714 
    ISSN: 0887-624X
    Keywords: coumarin derivatives ; photodimerization ; photocleavage ; reversible ; pho-tosensitizer ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Four photoreactive coumarin derivatives were successfully synthesized from 7-hydroxy-coumarin and 7-hydroxy-4-methylcoumarin, i.e., 7-propionyloxy-4-methylcoumarin (M1), 7-palmitoyloxy-4-methylcoumarin (M2), 7-propionyloxycoumarin (M3), and 7-palmitoy-loxycoumarin (M4). Reversible photodimerization (350 or 300 nm) and photocleavage (254 nm) of these coumarin derivatives dispersed in poly(vinyl acetate) (PVAc) were investigated by tracing their UV absorbance variations at 310 nm. The M2 and M4 with long palmitoyl chain show much better photoreaction reversibility than M1 and M3 with short propionyl chain. Moreover, photodimerization rate (under 350 nm) of M2 is greater than 200 times of that of M1. This has been explained by the formation of suitable conformation for revers-ible photodimerization due to the hydrophobic interactions. Photodimerization of M2 is ca. 3 times quicker than that of M4, indicating 4-methyl substitution enhances pho-todimerization. The influence of photodimerization wavelength (350 and 300 nm) and photosensitizer (benzophenone) have also been investigated in detail. © 1995 John Wiley & Sons. Inc.
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  • 90
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    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 2741-2752 
    ISSN: 0887-624X
    Keywords: 3,3′-bis (4-flurobenzoyl) biphenyl ; poly (aryl ether ketone)s ; spectroscopic prop-erties ; thermal properties ; thermomechancial properties ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A monomer, 3,3′-bis (4-fluorobenzoyl) biphenyl, was prepared in high yield in two steps from inexpensive 3-chlorobenzoyl chloride and fluorobenzene, and polymerized by nucleophilic displacement reaction with various bisphenol monomers in tetramethylene sulfone to produce a series of high molecular weight poly(aryl ether ketone)s containing 3,3′-dibenzoylbiphenyl (DBBP) moieties. The spectroscopic, thermal, and thermomechanical properties of these polymers and related isomeric polymers having 2,2′-and 4,4′-DBBP units were determined and compared to study the effects of changes in the substitution pattern of the biphenyl unit. Except for the 2,2′-DBBP series of polymers, Tgs were found to increase with increasing linearity of the DBBP unit. The 2,2′-DBBP series of polymers had exceptionally high Tgs due to the sterically restricted motions in the biphenyl unit caused by the 2,2′-substitution. In addition, they also showed evidence for torsion with the 2,2′-DBBP unit, whereas in other isomeric polymers the DBBP units are believed to be relatively coplanar. Thermal stabilities and tensile moduli for these polymers proved to be independent of substitution patterns. © 1995 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
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  • 91
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    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 2787-2793 
    ISSN: 0887-624X
    Keywords: Ziegler-Natta catalysis ; EPDM synthesis ; metallocene catalyst ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 4-Vinylcyclohexene (VCH) and cyclooctadiene (COD) were investigated as termonomers in EPDM (ethylene/propylene/diene) synthesis by using rac-ethylenebis (1-η5-indenyl) zir-conium dichloride (1) as a catalyst precursor. Homopolymerizations of VCH, vinylcycloh-exane and cyclohexene were compared. The parameter Kπκp, which is the apparent rate constant for Ziegler-Natta polymerization, is about the same for VCH and vinylcyclohexanebut is 10 times smaller for cyclohexene. Therefore, the linear olefinic double bond is more active than the cyclic internal double bond. VCH reduces ethylene polymerization rate but not propylene polymerization rate in copolymerizations. In terpolymerizations, VCH tends to suppress ethylene incorporation especially at elevated polymerization temperature and Lowers the polymer MW by about two-fold. COD has very low activity as a termonomer. © 1995 John Wiley & Sons, Inc.
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  • 92
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    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 2865-2873 
    ISSN: 0887-624X
    Keywords: fumarate ; radical polymerization ; addition-abstraction mechanism ; ESR spectrum ; propagation rate constant ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The radical polymerization behavior of ethyl ortho-formyl-phenyl fumarate (EFPF) using dimethyl 2,2′-azobisisobutyrate (MAIB) as initiator was studied in benzene kinetically and ESR spectroscopically. The polymerization rate (Rp) at 60°C was given by Rp = k[MAIB]0.76[EFPF]0.56. The number-average molecular weight of poly(EFPF) was in the range of 1600-2900. EFPF was also easily photopolymerized at room temperature without any photosensitizer probably because of the photosensitivity of the formyl group of monomer. Analysis of 1H- and 13C-NMR spectra of the resulting polymer revealed that the radical polymerization of EFPF proceeds in a complicated manner involving vinyl addition and intramolecular hydrogen-abstraction. The polymerization system was found to involve ESR-observable poly(EFPF) radicals under the actual polymerization conditions. ESR-determined rate constant (2.4-4.0 L/mol s) of propagation at 60°C increased with decreasing monomer concentration, which is mainly responsible for the observed low de-pendency of Rp on the EFPF concentration. Copolymerizations of EFPF with some vinyl monomers were also examined. © 1995 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
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  • 93
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    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 2841-2850 
    ISSN: 0887-624X
    Keywords: aromatic copolyesters ; poly(ethylene terephthalate) ; poly(ethylene naphtha-late) ; melt polycondensation ; physical properties ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Copolyesters containing rigid segments (naphthalene and terephthalene) and flexible seg-ments (aliphatic diol) structure were synthesized from DMN/DMT/EG (2,6-dimethyl naphthalate/1,4-dimethyl terephthalate/ethylene glycol) ternary monomers with various mole ratios. Copolyesters having intrinsic viscosities of 0.52-0.65 dL/g were obtained by melt polycondensation in the presence of metallic catalysts. The effect of reaction tem-perature and time on the formation of the copolyesters was investigated to obtain an op-timum condition for copolyester manufacturing. The optimum condition for PNT (poly-ethylene naphthalate terephthalate) copolyester manufacturing is the transesterification under nitrogen atmosphere for 4 h at a temperature of 185±2°C followed by polymerization under 2 mm Hg for 2 h at a temperature of 280°C. Most copolyesters have better solubilities than poly(ethylene naphthalate) (PEN) and poly(ethylene terephthalate) (PET) in various solvents. The effect of the starting mole ratio of DMN, DMT, and EG on the thermal properties of the resulted copolyesters was also investigated using differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). Glass transition temperatures of copolyesters were in the range of 70.7-115.2°C, and 10% weight loss in nitrogen were all above 426°C. © 1995 John Wiley & Sons, Inc.
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  • 94
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    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 2893-2899 
    ISSN: 0887-624X
    Keywords: poly(p-phenylenebenzobisthiazole) ; poly(p-phenylenebenzobisoxazole) ; fiber ; molecular composite fiber ; benzocyclobutene ; compressive strength ; tensile strength ; tensile modulus ; phase separation ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Fibers consisting of a rigid rod polymer and thermoset resin matrices were prepared. Poly(benzo-[1,2-d : 5,4-d′]bisoxazole-2,6-diyl)-1,4-phenylene} (PBO) in polyphosphoric acid (PPA) was blended with isophthaloyl bis-4-benzocyclobutene (1) or 2,6-bis-4-benzocyclobutene benzo[1,2-d: 5,4-d′]bisoxazole (2), and fibers were spun from these dopes. As-spun fibers that did not show phase segregation between the two components as examined with an optical microscope, were soluble in methanesulfonic acid (MSA). After heat treat-ment, the fibers swelled but did not dissolve in MSA. A fiber cross section of heat-treated PBO-1 fiber showed well-dispersed benzocyclobutene polymer domains of 200-500 Å by transmission electron microscopy (TEM). Films cast from MSA solutions of PBO and 2 were homogeneous, and TEM of heat-treated fiber showed only one phase. A molecular composite fiber was made. Some of these fibers showed 20-30% improvement in compressive strength over unmodified PBO fiber. © 1995 John Wiley & Sons, Inc.
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  • 95
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    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 2887-2892 
    ISSN: 0887-624X
    Keywords: plasma ; cascade arc ; surface modification ; fluorination ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The depth and possible mechanisms of the penetration of surface modification into porous media by a low temperature cascade are torch are investigated. Two different modes of such penetration (“flow controlled” and “diffusion controlled”) are evaluated. Three porous samples [stacks of 10 sheets of nonwoven fabrics of poly(ethylene terephthalate)each], placed at an axial distance of 24, 28, and 32 cm from the cascade are anode, are exposed to a low temperature cascade arc torch containing argon and CF4 or C2F4, and surface properties of each of the sheets within treated porous samples are examined by ESCA. It is shown that interaction of chemically reactive species, created in the low temperature cascade arc torch, with the surface is not limited to the surface directly contacted by the torch. The flow controlled penetration is more pronounced for the outer layers, while diffusion controlled penetration is within the inner layers of the porous structure. Substantial differences in the fluorination effect of CF4 (nonpolymer forming gas) and C2F4 (polymer forming gas) discharges for the second and third stacks are observed, that can be explained by the fact that the major effect of the CF4 cascade arc torch treatment is based on the reaction of reactive species with the surface polymer molecules. The effect of C2F4 cascade arc torch treatment is based on the reactions of reactive species with polymers as well as reactions of reactive species themselves at the surface (plasma polymerization). Reactivity of the species created in C2F4 discharge is much higher compared to that created in CF4 discharge, which is one of the major factors influencing penetration trends of low temperature cascade arc treatment into porous media. © 1995 John Wiley & Sons, Inc.
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    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 873-877 
    ISSN: 0887-624X
    Keywords: 4,4′-diamino-3′-nitrobenzanilide (DNB) ; poly-p-benzamide (PBA) ; poly-p-benzamide end-capped with nitro-p-phenylenediamine ; polyterephthalamide of 4,4′-diamino-3′-nitrobenzanilide ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Tab.
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  • 97
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    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 891-900 
    ISSN: 0887-624X
    Keywords: mercury-dithizone ; photochromic probes ; thermal relaxation rate ; free volume ; Tg ; thermal transition ; polystyrene ; poly(vinyl acetate) ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Mercury-dithizone complex both free and bonded to a polymeric system has been synthesized and used to measure the thermal transition of polystyrene, poly(vinyl acetate), and some other polymers. The thermal relaxation rate of the activated complex in dark has been found to be dependent on the free volume of a polymer matrix. The rate goes through a maximum above Tg of a polymer. A very sensitive method, based on thermal recovery of activated photochromic probe chromophore has been devised to measure the thermal transition of both single and multicomponent polymer matrices. © 1995 John Wiley & Sons, Inc.
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  • 98
    ISSN: 0887-624X
    Keywords: poly(ethylene oxide) ; (poly(oxy-1,2-ethanediyl) ; PEO ; hydrogen peroxide ; hydroxyl radicals ; hydroperoxyl radicals ; chain scission process ; oxidative degradation ; photodegradation ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Poly(ethylene oxide) (poly(oxy-1,2-ethanediyl) is rapidly oxidized by hydroxyl (HO•) and hydroperoxyl (HO•2) radicals generated by photolysis of hydrogen peroxide (H2O2) or by the catalytic decomposition of H2O2 by metallic silver. This process is accompanied by a chain scission during which the molecular weight decreases and the polydispersity changes. As a result of this process, the crystalline structure of poly(ethylene oxide) disappears, and the polymer becomes completely amorphous. © 1995 John Wiley & Sons, Inc.
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  • 99
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    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 979-987 
    ISSN: 0887-624X
    Keywords: Ziegler-Natta polymerization ; EPDM ; metallocene catalysts ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ethylene (E), propylene (P), and 1,4-hexadiene (HD) were terpolymerized with rac-1,2-ethylenebis (1-η5-indenyl) zirconium(IV) dichloride and methylaluminoxane (Et[Ind]2ZrCl2/MAO), and compared with the copolymerizations of E/P, E/HD, P/HD, and terpolymerization using ethylidene norbornene (ENB) as the termonomer. HD lowers the polymerization activity, the effect is more pronounced for P/HD and E/P/HD using large amount of P, than for E/HD and E/P/HD using feed low in P. The polymer molecular weight is most strongly affected by the temperature of polymerization (Tp), whereas the E/P ratio in the feed has virtually no effect. The reactivity ratios rE and rP are 3.0 and 0.3, respectively, at 20°C but rP becomes larger than rE at TP = 70°C. 1H-NMR spectra showed occurrence of cycloaddition in the homopolymerization of HD; on the other hand, HD is incorporated in the terpolymer only by linear 1,2-addition. © 1995 John Wiley & Sons, Inc.
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  • 100
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    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 1095-1105 
    ISSN: 0887-624X
    Keywords: 1,6-bis(4-aminophenoxy)naphthalene ; direct polycondensation ; polyamides ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new bis(phenoxy)naphthalene-containing diamine, 1,6-bis(4-aminophenoxy)naphthalene, was synthesized in two steps from the condensation of 1,6-dihydroxynaphthalene with p-chloronitrobenzene in the presence of potassium carbonate, giving 1,6-bis(4-nitrophenoxv)naphthalene, followed by hydrazine hydrate/Pd - C reduction. A series of polyamides were synthesized by the direct polycondensation of the diamine with various aromatic dicarboxylic acids in the N-methyl-2-pyrrolidone (NMP) solution containing dissolved metal salts such as CaCl2 or LiBr using triphenyl phosphite and pyridine as condensing agents. The polymers were obtained in quantitative yield with inherent viscosities of 0.78-3.72 dL/g. Most of the polymers were soluble in aprotic solvents such as N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), NMP, and they could be solution-cast into transparent, flexible and tough films. The casting films had tensile strength of 102-175 MPa, elongation at break of 8-42%, and tensile modulus of 2.4-3.8 GPa. The polymers derived from rigid dicarboxylic acids such as terephthalic acid and 4,4′-biphenyldicarboxylic acid exhibited some crystalline characteristics. The glass transition temperatures of the polyamides were in the range of 238-337°C, and their 10% weight loss temperatures were above 487°C in nitrogen and above 438°C in air. © 1995 John Wiley & Sons, Inc.
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