Journal of Polymer Science Part A: Polymer Chemistry

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

1 April 2002

Volume 40, Issue 7

Pages 809–922

  1. Articles

    1. Top of page
    2. Articles
    1. Structure–property relationships in modified natural rubber latexes grafted with methyl methacrylate and vinyl neo-decanoate (pages 809–822)

      Doug-Youn Lee, Nadaraja Subramaniam, Christopher M. Fellows and Robert G. Gilbert

      Version of Record online: 5 FEB 2002 | DOI: 10.1002/pola.10165

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      A series of modified natural rubber latexes (NRL) grafted with poly(methyl methacrylate) (PMMA) were prepared by seeded emulsion polymerization with two different hydroperoxides used to initiate polymerization in a redox system with tetraethylenepentaamine (TEPA). The system containing the more hydrophobic hydroperoxide was observed to be more efficient for grafting of secondary polymers and gave greater phase mixing. This suggests that grafting is related to the flux of oxygen-centered radicals within the NR particles. Enhanced phase mixing was also obtained in the presence of vinyl neo-decanoate (VneoD), attributed to the VneoD-rich MMA-VneoD copolymer formed late in the reaction. This has a solubility parameter between that of PMMA and NR. Changes in viscoelastic behavior consistent with the presence of a high-Tg mixed phase were observed with increasing grafting and poorer film formation was observed consistent with the localization of a high Tg secondary polymer phase near the particle surface. Apparent concentration of PMMA near the surface of particles was also observed by transmission electron microscopy. The control of phase mixing and branching given by these procedures may help improve the suitability of these materials as components in pressure-sensitive adhesive formulations.

    2. Hyperbranched aryl polycarbonates derived from A2B monomers versus AB2 monomers (pages 823–835)

      Daniel H. Bolton and Karen L. Wooley

      Version of Record online: 5 FEB 2002 | DOI: 10.1002/pola.10167

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      Hyperbranched aryl polycarbonates were prepared that contained a backbone chemistry chemically similar to that of bisphenol A polycarbonate, although their overall compositions were nonequivalent. The chain-end functionalities of the hyperbranched polycarbonates were controlled by the polymerizations of A2B and AB2 monomers and postpolymerization chemical derivatization reactions.

    3. Polymerization of sterically congested α-alkylacrylates under high pressure (pages 836–843)

      Javid Rzayev and Jacques Penelle

      Version of Record online: 5 FEB 2002 | DOI: 10.1002/pola.10161

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      A series of α-alkylacrylates, including methyl ethacrylate (MEA), methyl α-propylacrylate, methyl α-isopropylacrylate, methyl α-butylacrylate (MnBA), and methyl α-isobutylacrylate (MiBA), were successfully polymerized under high pressure (1–9 kbar) to yield high molecular weight polymers. Polymerization kinetics under high pressure were obtained for MEA, MnBA, and MiBA. Extrapolation to ambient pressure provided rates of polymerization for these monomers unaffected by the ceiling temperature effect. These values were further used to quantitatively assess the steric influence exerted by the α-substituent on the polymerizability of these sterically congested acrylates with Meyer's steric parameter.

    4. Phosphines: Nucleophilic organic catalysts for the controlled ring-opening polymerization of lactides (pages 844–851)

      Matthew Myers, Eric F. Connor, Thierry Glauser, Andreas Möck, Gregory Nyce and James L. Hedrick

      Version of Record online: 6 FEB 2002 | DOI: 10.1002/pola.10168

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      An organocatalytic approach to the controlled synthesis of polylactide in solution and melt is presented. P(Bu)3, PhPMe2, Ph2PMe, PPh3, and related phosphines are commercially available, inexpensive catalysts that generate narrowly dispersed polylactides with predictable molecular weights. A plausible polymerization mechanism is nucleophilic activation of the monomer.

    5. Poly(ethylene terephthalate) reinforced by N,N′-diphenyl biphenyl-3,3′,4,4′-tetracarboxydiimide moieties (pages 852–863)

      Jun Xiao, Xinhua Wan, Dong Zhang, Hailiang Zhang, Qi-Feng Zhou and S. Richard Turner

      Version of Record online: 11 FEB 2002 | DOI: 10.1002/pola.10169

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      A novel rodlike imide-containing monomer, N,N′-bis[p-(methoxy carbonyl) phenyl]-biphenyl-3,3′,4,4′-tetracarboxydiimide, was incorporated at low levels into a poly(ethylene terephthalate) (PET) backbone by a standard melt-phase polycondensation technique with dimethyl terephthalate and ethylene glycol. Copolyesters containing 1–7 mol % of the imide monomer exhibited a significant reinforcing effect on PET even at these modest incorporation levels. Enhanced glass-transition temperatures, tensile moduli, and tensile strengths confirmed that these compositions could offer a feasible approach for obtaining polyesters with enhanced properties.

    6. Anionic ring-opening polymerization of propylene oxide in the presence of phosphonium catalysts (pages 864–873)

      Ornulf Rexin and Rolf Mülhaupt

      Version of Record online: 6 FEB 2002 | DOI: 10.1002/pola.10163

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      Anionic ring-opening polymerization of propylene oxide in the presence of potassium alcoholate initiator was accelerated by addition of the bulky phosphonium salt tetrakis[cyclohexyl(methyl)amino]phosphonium-tetrafluoroborate. Dipropylene glycol was partially deprotonated (5%) and used as an initiator. The delocalization of the positive charge over five atoms promoted the formation of a separated ion pair, thus enhancing nucleophilicity and reactivity. Compared with those of polyaminophosphazenes and tetrabutylphosphonium cation, the average propagation rates increased in the order of Bu4P+, K+, Pmath image, Pmath image, and tBuP4H+. Characterization of poly(propylene oxide)s by means of 1H NMR, size exclusion chromatography, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry showed low polydispersities without any byproducts or impurities. Determination of the total degree of unsaturation indicated larger amounts with increasing polymerization rates.

    7. Synthesis of amphiphilic particles in the presence of inert solvents and their application to lipase immobilization (pages 874–884)

      Masahiro Yasuda, Miho Kobayashi, Shinji Watanabe, Hiroyasu Ogino, Kosaku Ishimi and Haruo Ishikawa

      Version of Record online: 19 FEB 2002 | DOI: 10.1002/pola.10178

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      To develop monodisperse amphiphilic polymer particles on which a large amount of lipase could be immobilized, we performed seed polymerizations of glycidyl methacrylate and allyl methacrylate in the presence of nonpolar inert and polar inert solvents. The amphiphilic porous polymer particles, with both hydrophilic guanidino groups and hydrophobic acyl groups, were synthesized, and they had macropores with diameters of 50–1000 nm. The amount of lipase immobilized on the amphiphilic particles was 3.85 times that in similar particles synthesized in the absence of a solvent, and the immobilized lipase exhibited a high transesterification activity in n-hexane and could be used repeatedly without a considerable activity loss.

    8. Synthesis and thermal properties of hybrid copolymers of syndiotactic polystyrene and polyhedral oligomeric silsesquioxane (pages 885–891)

      Lei Zheng, Rajeswari M. Kasi, Richard J. Farris and E. Bryan Coughlin

      Version of Record online: 11 FEB 2002 | DOI: 10.1002/pola.10175

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      Copolymerizations of styrene and the polyhedral oligomeric silsesquioxane (POSS)–styryl macromonomer 1-(4-vinylphenyl)-3,5,7,9,11,13,15-heptacyclopentylpentacyclo [9.5.1.13,9.15,15.17,13] octasiloxane (1) have been performed with CpTiCl3 in conjunction with methylaluminoxane. Random copolymers of syndiotactic polystyrene (sPS) and POSS copolymers have been formed and fully characterized. NMR reveals a moderately high syndiotacticity of the polystyrene backbone consistent with this CpTiCl3 catalyst and POSS loadings as high as 24 wt % and 3.2 mol %. Thermogravimetric analysis of the sPS–POSS copolymers under both nitrogen and air shows improved thermal stability with higher degradation temperatures and char yields.

    9. Surface modification of polystyrene latex particles via atom transfer radical polymerization (pages 892–900)

      Ke Min, Jianhua Hu, Changchun Wang and Abdelhamid Elaissari

      Version of Record online: 13 FEB 2002 | DOI: 10.1002/pola.10160

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      Atom transfer radical polymerization was applied to prepare novel core-shell particles. The seed polystyrene particles, which were produced by emulsifier-free polymerization, were used as macroinitiators for the graft reaction of linear poly(methyl methacrylate) (PMMA) and poly(methyl acrylate) (PMA). The core-shell particles were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, nuclear magnetic resonance, and scanning electron microscopy.

    10. Tetraalkylammonium salt as photoinitiator of vinyl polymerization in organic and aqueous media: A mechanistic and laser flash photolysis study (pages 901–913)

      María L. Gómez, Rodrigo E. Palacios, Carlos M. Previtali, Hernán A. Montejano and Carlos A. Chesta

      Version of Record online: 14 FEB 2002 | DOI: 10.1002/pola.10166

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      N-Dimethyl-N-[2-(N,N-dimethylamino)ethyl]-N-(1-methylnaphthyl)- ammonium tetrafluoroborate (I) was synthesized with the aim of obtaining a versatile photoinitiator for vinyl polymerization in organic solvents and water. Salt I was able to trigger the polymerization of acrylamide, 2-hydroxyethylmethacrylate, and styrene. With irradiation, I undergoes an intramolecular electron-transfer reaction to form a radical ion pair (RIP). The RIP intermediate decomposes into free radicals. At large monomer concentrations the RIP state triggers the reaction by generating the anion radical of the olefin substrate. At a low monomer concentration, the free radicals produced by the decomposition of I starts the chain reaction.

    11. Complex formation of polyethyleneimine with copper(II), nickel(II), and cobalt(II) ions (pages 914–922)

      V. N. Kislenko and L. P. Oliynyk

      Version of Record online: 19 FEB 2002 | DOI: 10.1002/pola.10157

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      An influence of the structure of a globule of polyethyleneimine on the complex formation of one with the copper(II), nickel(II), and cobalt(II) ions is described. A change of the coordination number from the pH of solution for complexes of ethylenediamine, diethylenetriamine, and polyethyleneimine with metal ions was found. The fraction of monomer links, bound with metal ions, depends on the volume of the globule of macromolecule as well as the condition of the proceeding reaction. The reaction of complex formation is controlled by the diffusion of metal ions into the polymer globule in solution. The effective equilibrium constants of complex formation were found.

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