Journal of Polymer Science Part A: Polymer Chemistry

Cover image for Journal of Polymer Science Part A: Polymer Chemistry

15 February 2003

Volume 41, Issue 4

Pages 457–623

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      Hyperbranched polyethers by ring-opening polymerization: Contribution of activated monomer mechanism (pages 457–468)

      Przemysław Kubisa

      Version of Record online: 20 DEC 2002 | DOI: 10.1002/pola.10605

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      Cationic polymerization of 3-alkyl-3-hydroxymethyloxetane gives medium-molecular-weight branched polyethers containing multiple terminal hydroxymethyl groups. Cyclization occurring in the course of the polymerization leads to compact structure. Copolymerization with bis(hydroxymethyl) or bis(oxetane) analogues allows (to some extent) an increased degree of branching and molecular weight of branched multihydroxyl polyethers.

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    1. Ultraviolet–ultraviolet dual-cure process based on acrylate oxetane monomers (pages 469–475)

      Abdelkrim El-ghayoury, Chouaib Boukaftane, Barteld de Ruiter and Rob van der Linde

      Version of Record online: 20 DEC 2002 | DOI: 10.1002/pola.10600

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      A dual-cure process consisting of two subsequent UV-initiated radical and cationic polymerizations has been investigated, using two acrylate-oxetane monomers. Realtime FTIR studies showed that 86% of the acrylate and 80% of the oxetane moieties were converted after 20 s and 50 s of light exposure, respectively.

    2. Pd(0)-catalyzed polyaddition of bifunctional vinyloxiranes with phenol derivatives: The synthesis of polymers containing an allyl aryl ether moiety in the main chain (pages 476–482)

      Toshio Koizumi, Takao Imai and Takeshi Endo

      Version of Record online: 20 DEC 2002 | DOI: 10.1002/pola.10588

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      The Pd(0)-catalyzed polyaddition of bifunctional vinyloxiranes (1a and 1b) with phenol derivatives such as hydroquinone and bisphenol A was performed in tetrahydrofuran in the presence of Pd(PPh3)4 or Pd2(dba)3 · CHCl3/dppe as a catalyst [where dba is dibenzylideneacetone and dppe is 1,2-bis(diphenylphosphino)ethane] and gave new unsaturated polyethers with an allyl aryl ether moiety and pendant hydroxy groups in good yields.

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    1. Important role of Si main chain for solvatochromism in poly[bis(4-propoxybutyl)silylene] (pages 483–486)

      Yuuichi Orimoto and Yuriko Aoki

      Version of Record online: 20 DEC 2002 | DOI: 10.1002/pola.10586

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      The ab initio molecular orbital approach suggested that polysilane oligomer has a tendency to prefer a trans zigzag-type structure rather than a random structure when the molecule is charged. Such unique behavior in the rotational barrier of charged polysilane has the potential for a description of solvatochromic transition in conformation of the Si main chain in poly[bis(4-propoxybutyl)silylene] when acids are added.

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    1. Anionic copolymerization of hexanelactam with functionalized polyisoprene (pages 487–496)

      R. Mateva, R. Filyanova, R. Velichkova and V. Gancheva

      Version of Record online: 2 JAN 2003 | DOI: 10.1002/pola.10599

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      Block copolymers of the A-B-C-B-A type were synthesized for the first time via the activated anionic polymerization of hexanelactam (HL) with Na-HL as an initiator and macroactivators [or polymeric activators (PACs)] as elastificators for nylon-6. The PACs were prepared by the functionalization of telechelic hydroxyl-terminated poly(ethylene oxide)–polyisoprene–poly(ethylene oxide) copolymers with different diisocyanates. Hexamethylene diisocyanate (1,6-diisocyanatohexane) and isophorone diisocyanate (5-isocyanate1-isocyanatomethyl-1,3,3-trimetylcyclohexane) were used as functionalizing agents. This article reports on the effects that the various central elastomeric PAC blocks (type, content, and molecular weight) had on the polymerization kinetics and on the structure and molecular weights of the multiblock copolymers obtained.

    2. Synthesis and characterization of sulfonated poly(phthalazinone ether ketone) for proton exchange membrane materials (pages 497–507)

      Yan Gao, Gilles P. Robertson, Michael D. Guiver and Xigao Jian

      Version of Record online: 3 JAN 2003 | DOI: 10.1002/pola.10601

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      Series of sulfonated poly(phthalazinone ether ketone)s (SPPEK)s were prepared by modification of poly(phthalazinone ether ketone) (PPEK) as a novel class of proton exchange membrane materials for use in fuel cells. Sulfonation reactions were conducted with mixtures of concentrated and 27–33% fuming sulfuric acid with different acid ratios in order to get SPPEK with degree of sulfonation (DS) in the desired range of 0.6–1.2. The DS, structures, and selected physical properties relevant to their intended fuel cell application were fully characterized by NMR and other methods. Membrane films of SPPEKs with DS ≥ 1.0 had good proton conductivities above 10−2 S/cm.

    3. Local chain-configuration dependence of the mechanisms of the chemical reaction of poly(vinyl chloride). IX. Novel results on stereoselectivity of chlorination reaction (pages 508–519)

      G. Martínez, J. Millán and J. Contreras

      Version of Record online: 6 JAN 2003 | DOI: 10.1002/pola.10603

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      A PVC sample was chlorinated in solution in the presence of 2,2′-azobisisobutyronitrile in solution and by the fluid-bed method. The quantitative microstructural analysis of residual poly(vinyl chloride) with a degree of chlorination followed by 13C NMR spectroscopy unambiguously inferred that the chlorination reaction proceeds by a stereoselective mechanism in that the mr heterotactic triads are the most reactive structures followed by the isotactic triad at mmmr and rmmr pentads.

    4. Degradable poly(ethylene oxide) hydrogels formed by crosslinking with tert-butylperoxybenzoate (pages 520–527)

      Shahriar Hojjati Emami, Ronald Salovey and Thieo E. Hogen-Esch

      Version of Record online: 2 JAN 2003 | DOI: 10.1002/pola.10593

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      Crosslinking of poly(ethylene oxide) (PEO) by t-butylperbenzoate gives in the presence of bis-peroxides acetals and/or orthoesters or similar species that are predicted to undergo PEO cleavage upon swelling the gels with dilute acids. This idea is supported by the decrease of the elastic modulus loss with time in the presence of 0.02 M sulfuric acid. The unmodified PEO does not undergo a similar chain cleavage as demonstrated by viscosity measurements

    5. Synthesis of branched polyethylenes by the tandem catalysis of silica-supported linked cyclopentadienyl-amido titanium catalysts and a homogeneous dibromo nickel catalyst having a pyridylimine ligand (pages 528–544)

      Kittichote Musikabhumma, Thomas P. Spaniol and Jun Okuda

      Version of Record online: 3 JAN 2003 | DOI: 10.1002/pola.10597

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      The synthesis of branched polyethylenes by heterogeneous ethylene polymerization with new tandem catalyst systems based on methylaluminoxane-preactivated linked cyclopentadienyl-amido titanium catalysts, supported on pyridylethylsilane-modified silica (PySTiNMe and PySTiNtBu), and a homogeneous dibromo(pyridylimine)nickel catalyst (PyminNiBr2), activated by modified methylaluminoxane, is reported. The synthesis of branched polyethylenes with tandem catalyst systems of the corresponding homogeneous titanium catalysts and the nickel catalyst has also been investigated for comparison.

    6. Electrospun nanofibers: Internal structure and intrinsic orientation (pages 545–553)

      R. Dersch, Taiqi Liu, A. K. Schaper, A. Greiner and J. H. Wendorff

      Version of Record online: 2 JAN 2003 | DOI: 10.1002/pola.10609

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      The internal structure of electrospun fibers of polyamide-6 and polylactide was investigated. Despite the rapid structure formation process, the degree of crystallinity was not significantly smaller than that found for less rapidly quenched and much thicker samples. The orientation of the crystals along the fiber axis was strongly inhomogeneous.

    7. Novel side-chain liquid-crystalline polyimide for film materials (pages 554–559)

      Haojun Fan, Yi Gu and Meili Xie

      Version of Record online: 2 JAN 2003 | DOI: 10.1002/pola.10596

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      The synthesis of SLCPI included two steps: After diamines were dissolved in NMP at 0 °C in an ice-water bath, the dianhydride monomer (ODPA) was added with magnetic stirring. The reaction was carried out for 10 h, after which a polyamic acid (PAA) was obtained. The PAA solution was then casted on a glass to imidize at 100 °C for 2 h, 200 °C for 2 h, 300 °C for 2 h under −0.9 atm. Then the SLCPI films were prepared.

    8. Molecular weight control of polyacrylamide with sodium formate as a chain-transfer agent: Characterization via size exclusion chromatography/multi-angle laser light scattering and determination of chain-transfer constant (pages 560–568)

      Michael J. Fevola, Roger D. Hester and Charles L. McCormick

      Version of Record online: 2 JAN 2003 | DOI: 10.1002/pola.10594

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      The molecular weights of polyacrylamide (PAM) homopolymers were controlled by the addition of sodium formate (NaOOCH) to the polymerization medium as a conventional chain-transfer agent. Data derived from extensive polymer characterization were used to determine the chain-transfer constant to NaOOCH and to calculate Mark–Houwink–Sakurada K and a values for PAM in 0.514 M NaCl at 25 °C.

    9. Preparation of supported yttrium alkoxides as catalysts for the polymerization of lactones and oxirane (pages 569–578)

      E. Martin, Ph. Dubois and R. Jerome

      Version of Record online: 2 JAN 2003 | DOI: 10.1002/pola.10608

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      [Tris(hexamethyldisilyl)-amide]yttrium {Y[N(SiMe3)2]3} is an ideal precursor for supporting Y alkoxides on silica particles, which can be used afterward as heterogeneous catalysts in the ring-opening polymerization of lactones and oxirane.

    10. Monitoring photopolymerization reactions with optical pyrometry (pages 579–596)

      Benjamin Falk, Santiago M. Vallinas and James V. Crivello

      Version of Record online: 3 JAN 2003 | DOI: 10.1002/pola.10602

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      Optical pyrometry is a new analytical technique for the continuous monitoring of the progress of both free-radical and cationic photopolymerizations. The method is rapid, reproducible, and very easy to implement.

    11. Polystyrene latices containing dodecanamide-modified poly(propyleneimine) dendrimers (pages 597–605)

      Zushun Xu and Warren T. Ford

      Version of Record online: 6 JAN 2003 | DOI: 10.1002/pola.10604

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      Polymerization of styrene in aqueous dispersions of the dodecanamide derivative of poly(propyleneimine) dendrimer DAB-dendr-(NH2)64 and sodium dodecyl sulfate (SDS) produced stable latices. With initial SDS concentrations of 10 mM or less, molar ratios of SDS to dendrimer end groups ranging from 2.3:1 to 9.5:1, and less than 10 wt % of SDS relative to styrene, the polystyrene latices had diameters of 30–60 nm and coefficients of variation of diameters of less than 10% when measured by transmission electron microscopy. Higher concentrations of SDS gave more polydisperse latices. The polystyrene latices formed with SDS and the dodecanamide-modified dendrimer were almost the same size and polydispersity as those formed with SDS and the parent primary amine dendrimer DAB-dendr-(NH2)64.

    12. Crosslinking polymerization leading to interpenetrating polymer network formation. I. Polyaddition crosslinking reactions of poly(methyl methacrylate-co-2-methacryloyloxyethyl isocyanate)s with ethylene glycol resulting in polyurethane networks (pages 606–615)

      Tadahiro Kiguchi, Hiroyuki Aota and Akira Matsumoto

      Version of Record online: 6 JAN 2003 | DOI: 10.1002/pola.10615

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      The polyaddition crosslinking reactions of poly(methyl methacrylate-co-2-methacryloyloxyethyl isocyanate) [poly(MMA-co-MOI)], having various functionalities, with ethylene glycol led to polyurethane networks, and they were investigated to clarify the interpenetrating polymer network (IPN) formation mechanism, in which the IPNs consisted of both polymethacrylate and polyurethane networks. The actual gel points were compared with the theoretical ones calculated according to Macosko's equation for f-functional polyisocyanate/diol polyaddition crosslinking reactions. The deviation of the actual gel point from the theoretical value became more remarkable for a greater functionality of poly(MMA-co-MOI) and at a lower isocyanate group concentration or a lower poly(MMA-co-MOI) concentration.

    13. Possible structural effect of a′,b′-dihydroxyacetophenone units in the preformed oligoesters upon copolycondensation with isomeric c′,d′-dihydroxyacetophenones by TsCl/dimethylformamide/pyridine (pages 616–623)

      Fukuji Higashi and Masato Koshio

      Version of Record online: 6 JAN 2003 | DOI: 10.1002/pola.10592

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      A two-stage copolycondensation of an equimolar mixture of isophthalic acid and terephthalic acid first with a′,b′-dihydroxyacetophenones (a′,b′-DHAPs) and then with isomeric c′,d′-DHAPs was examined to investigate the structural effect of a′,b′-DHAP moieties in the preformed oligomers on the reactions with isomeric c′,d′-DHAPs. The results are discussed from the inherent viscosity values of the resultant copolymers and from the change of way in which the preformed oligomers react with the next monomers by analyzing the distributions of the resulting oligomers determined by gel permeation chromatography.

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