Journal of Polymer Science Part A: Polymer Chemistry

Cover image for Vol. 42 Issue 16

15 August 2004

Volume 42, Issue 16

Pages 3911–4100

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      The discovery of metallocene catalysts and their present state of the art (pages 3911–3921)

      Walter Kaminsky

      Article first published online: 9 JUL 2004 | DOI: 10.1002/pola.20292

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      The combination of metallocene complexes with methylaluminoxane (MAO) leads to extremely active catalysts for olefin polymerization. By variation of the ligands of the transition metal complexes, a catalyst to tailor the microstructure of polymers such as comonomer distribution, stereo-, and regioregularity, which was not possible before, is obtained.

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    1. Two-dimensional polymer synthesis through the topochemical polymerization of alkylenediammonium muconate as a multifunctional monomer (pages 3922–3929)

      Sadamu Nagahama and Akikazu Matsumoto

      Article first published online: 6 JUL 2004 | DOI: 10.1002/pola.20237

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      Here we demonstrate a unique two-dimensional polymer synthesis through topochemical polymerization via polymer crystal engineering. We have succeeded in the synthesis of a sheet polymer through the polymerization of alkylenediammonium (Z,Z)-muconate as a multifunctional 1,3-diene monomer in the crystalline state under the irradiation of UV and γ-rays or upon heating in the dark. The stereochemical structure of the polymer and the polymerization mechanism are discussed on the basis of the results of IR and NMR spectroscopy, thermogravimetric measurements, and solid-state hydrolysis for the transformation into poly(muconic acid).

    2. Direct measurement of structural diversity in single molecules of a chiral helical π-conjugated polymer (pages 3930–3935)

      Ken-ichi Shinohara, Takeshi Kitami and Kouichi Nakamae

      Article first published online: 9 JUL 2004 | DOI: 10.1002/pola.20247

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      Using a noncontact atomic force microscope, we found that single molecules in a chiral helical π-conjugated polymer could form a unique periodic structure having a pitch of about 20 nm on the surface of a mica substrate. The diversity of the periodic structures is also discussed. Some basic insights into the characteristics of single molecules (or their individual characteristics) in π-conjugated polymers are revealed.

    3. Effect of the particle size distribution on the low shear viscosity of high-solid-content latexes (pages 3936–3946)

      Marcelo Do Amaral, Steven Van Es and José M. Asua

      Article first published online: 6 JUL 2004 | DOI: 10.1002/pola.20269

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      Despite important progress in theoretical work, not much has been done to quantitatively predict the low shear viscosity of aqueous polymer dispersions as a function of the complex particle size distribution. In this work, the capability of a low-shear-viscosity equation to quantitatively account for the influence of both the particle size distribution and the physicochemical characteristics of the dispersions is experimentally assessed. An analysis, consistent with theoretical concepts, of the data with semiempirical correlations is proposed. Next, with values of the parameters of the viscosity equation obtained experimentally, the effect of a latex with a 70% solid content on the low shear viscosity is examined.

    4. Soluble, saturated-red-light-emitting poly(p-phenylenevinylene) containing triphenylamine units and cyano groups (pages 3947–3953)

      Hongchao Li, Yufeng Hu, Yanguang Zhang, Dongge Ma, Lixiang Wang, Xiabin Jing and Fosong Wang

      Article first published online: 12 JUL 2004 | DOI: 10.1002/pola.20278

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      Saturated-red-light-emitting poly(p-phenylenevinylene) containing triphenylamine and cyano groups was designed and synthesized with the donor–acceptor strategy. Optical studies suggested that the polymer film fluoresced a bright and saturated red emission with a maximum at 650 nm. A single-layer device emitted pure red light at 633 nm.

    5. Synthesis and characterization of new light-emitting copolymers in polymeric-light-emitting-diode device fabrications (pages 3954–3966)

      Sheng-Han Wu, Chi-Hsien Shen, Jar-Hung Chen, Chia-Chen Hsu and Raymond Chien-Chao Tsiang

      Article first published online: 12 JUL 2004 | DOI: 10.1002/pola.20283

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      A series of thiophene-containing photoactive copolymers consisting of alternating conjugated and nonconjugated segments were synthesized. The energy levels (HOMO and LUMO) of all copolymers were lower than those of MEH–PPV indicative of a balanced hole/electron injection, thus leading to the improved performances of both single-layered and double-layered PLED devices. All copolymers emitted bluish-green to green light above the threshold bias of 5.0 V under the ambient condition, and the external EL efficiency (cd/A) decreased with the lifetime as the polymer degraded.

    6. Mechanism of the formation of stable microspheres by precipitation copolymerization of styrene and divinylbenzene (pages 3967–3974)

      Sang Eun Shim, Sunhye Yang and Soonja Choe

      Article first published online: 12 JUL 2004 | DOI: 10.1002/pola.20188

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      A mechanism explaining the growth of microspheres in the precipitation polymerization of styrene and divinylbenzene was proposed based on the morphology, circularity, and specific surface area. Once the stable particles are generated by the aggregation of the primary nucleus particles, they grow by absorbing oligomeric species without generating substantial pores.

    7. Tunable block copolymers based on a polysiloxane backbone by anionic ring-opening polymerization (pages 3975–3985)

      Josef Bauer, Nicola Hüsing and Guido Kickelbick

      Article first published online: 12 JUL 2004 | DOI: 10.1002/pola.20282

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      Poly(dimethylsiloxane)–poly(vinylmethylsiloxane) diblock copolymers were obtained through the anionic ring-opening polymerization of cyclotrisiloxane containing the appropriate organic groups. Functional groups in the vinyl-modified segment were completely transferred to the epoxides, which were subsequently ring-opened with several nucleophiles. The epoxide-opening reaction parameters were optimized to prevent crosslinking and to enhance the conversion of the epoxide groups.

    8. Low dielectric thermoset. IV. Synthesis and properties of a dipentene-containing cyanate ester and its copolymerization with bisphenol A dicyanate ester (pages 3986–3995)

      Ching Hsuan Lin, Chu Nan Hsiao, Chun Hung Li and Chun Shan Wang

      Article first published online: 10 AUG 2004 | DOI: 10.1002/pola.20226

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      A 2,6-dimethylphenol-dipentene dicyanate ester (DPCY) was synthesized from the reaction of a 2,6-dimethylphenol-dipentene adduct and cyanogen bromide. DPCY was then cured by itself or cured with bisphenol A dicyanate ester (BADCY). The cured DPCY exhibits a lower dielectric constant, dissipation factor, thermal stability, glass transition temperature, coefficient of thermal expansion, and moisture absorption than those of BADCY, but higher moduli than those of the bisphenol A system.

    9. Mechanistic aspects of ester–carbonate exchange in polycarbonate/cycloaliphatic polyester with model reactions (pages 3996–4008)

      M. Jayakannan and P. Anilkumar

      Article first published online: 9 JUL 2004 | DOI: 10.1002/pola.20281

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      The reactive blending of bisphenol A polycarbonate (PC) with poly(1,4-cyclohexanedimethylene-1,4-cyclohexanedicarboxylate) (PCCD) was investigated with NMR and Fourier transform infrared spectroscopy. Model reactions were carried out through the reaction of PC with 1,4-dimethylcyclohexanedicarboxylate, 1,4-cyclohexanedicarboxylic acid, and 1,4-cyclohexanedimethanol to study the tendency of polyester chain-end reactions such as transesterification, acidolysis, and alcoholysis. These model reactions revealed that the reactive blending was affected by both alcoholysis and transesterification, whereas acidolysis was absent. NMR analysis confirmed that in PC/PCCD reactive blending, the exchange reaction predominantly occurred in the polymer main chains, and the influence of the end groups was insignificant.

    10. Photopolymerization of 1,6-hexanedioldiacrylate initiated by three-component systems based on N-arylphthalimides (pages 4009–4015)

      T. Brian Cavitt, Brian Phillips, Charles E. Hoyle, Bo Pan, Sukhendu B. Hait, Kalyanaraman Viswanathan and Sonny Jönsson

      Article first published online: 12 JUL 2004 | DOI: 10.1002/pola.20022

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      Three-component photoinitiators comprised of an N-arylphthalimide, a diarylketone, and a tertiary amine were investigated for their initiation efficiency of acrylate polymerization. The use of an electron-deficient N-arylphthalimide resulted in a greater acrylate polymerization rate than an electron-rich N-arylphthalimide. Triplet energies of each N-arylphthalimide, determined from their phosphorescence spectra, and the respective rate constants for triplet quenching by the N-arylphthalimide derivatives (acquired via laser flash photolysis) indicated that an electron–proton transfer from an intermediate radical species to the N-arylphthalimide (not energy transfer from triplet sensitization) is responsible for generating the initiating radicals under the conditions and species concentrations used for polymerization.

    11. Expanding the supramolecular polymer LEGO system: Nitroxide-mediated living free-radical polymerization as a tool for mono- and telechelic polystyrenes (pages 4016–4027)

      Bas G. G. Lohmeijer and Ulrich S. Schubert

      Article first published online: 12 JUL 2004 | DOI: 10.1002/pola.20189

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      Nitroxide mediated controlled living radical polymerization has been employed for the introduction of terpyridine ligands at one or two chain ends of polystyrene of different molecular weights.

    12. Free radical and thermal curing of terpyridine-modified terpolymers (pages 4028–4035)

      Harald Hofmeier, Abdelkrim El-Ghayoury and Ulrich S. Schubert

      Article first published online: 12 JUL 2004 | DOI: 10.1002/pola.20253

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      Terpolymers containing terpyridine as supramolecular binding units as well as olefinic groups suitable for free radical crosslinking have been prepared and investigated. Furthermore, thermal crosslinking of a terpyridine-containing terpolymer bearing hydroxy-groups with bis-isocyanate was successfully combined with noncovalent crosslinking.

    13. Synthesis, characterization, and curing kinetics of novel ladder-like polysilsesquioxanes containing side-chain maleimide groups (pages 4036–4046)

      P. Santhana Gopala Krishnan, Chaobin He and Christine Tay Shang Shang

      Article first published online: 9 JUL 2004 | DOI: 10.1002/pola.20243

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      Two ladder-like polysilsesquioxanes (LPS) containing side-chain maleimide groups were synthesized successfully by reacting LPS-containing chloropropyl groups with N-(4-hydroxyphenyl)maleimide and characterized. Characterization data indicated that they have ladder-like structures, although the existence of some structural defects is not ruled out. Curing kinetics were investigated by the dynamic DSC method.

    14. Synthesis and deblocking of cardanol- and anacardate-blocked toluene diisocyanates (pages 4047–4055)

      A. Sultan Nasar, V. Shrinivas, T. Shanmugam and A. Raghavan

      Article first published online: 12 JUL 2004 | DOI: 10.1002/pola.20211

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      Cardanol-, methyl anacardate-, and sec-butylanacardate-blocked 2,4-toluene diisocyanate adducts were prepared, and the deblocking reactions involving these adducts were investigated. It was found that the presence of the electron-withdrawing ester group reduced the deblocking temperature of the adduct only when the adduct was solvated. Analysis of deblocking temperatures and gel times revealed that cardanol-blocked 2,4-toluene diisocyanate adducts underwent deblocking at a lower temperature and at a higher rate compared with anacardate-blocked adducts.

    15. Synthesis and properties of novel soluble polyamides having ether linkages and laterally attached p-terphenyl units (pages 4056–4062)

      Sheng-Huei Hsiao and Yu-Min Chang

      Article first published online: 12 JUL 2004 | DOI: 10.1002/pola.20187

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      A new aromatic bis(ether-carboxylic acid), 2′,5′-bis(4-carboxyphenoxy)-p-terphenyl (3), was synthesized by the aromatic substitution reaction of p-fluorobenzonitrile with 2′,5′-dihydroxy-p-terphenyl in the presence of potassium carbonate, followed by alkaline hydrolysis. A set of new aromatic polyamides, 5ai, containing ether and laterally attached p-terphenyl units was synthesized by direct phosphorylation polycondensation of diacid 3 with nine aromatic diamines. Most of the polyamides were characterized by good solubility in highly polar solvents, good film-forming ability, and moderate to high thermal stability.

    16. Poly(methyl methacrylate) encapsulation of calcium carbonate particles (pages 4063–4073)

      Soo Duk Seul, Sun Ryong Lee and Young Han Kim

      Article first published online: 12 JUL 2004 | DOI: 10.1002/pola.20207

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      Dispersed calcium carbonate particles are encapsulated with poly(methyl methacrylate) (PMMA). From the conversion comparison of the MMA monomer it is found that the optimum concentration of polymerization initiator is 1.58 × 10−3 mol/L. The highest yield of encapsulation is obtained at 250 rpm with a concentration of 0.5 wt % surfactant (sodium dodecyl benzene sulfonate). A comparison of the Fourier transform IR spectra distinctly indicates the formation of PMMA on the surface of the calcium carbonate particles. In addition, thermal analyses and microscopic observation characterize the PMMA on the surface of encapsulated particles.

    17. Synthesis and inhibition performance of a polymer-supported inhibitor (pages 4074–4083)

      Peng Yang, Yufeng Sun, Jianyuan Deng, Weina Liu, Li Zhang and Wantai Yang

      Article first published online: 9 JUL 2004 | DOI: 10.1002/pola.20238

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      The synthesis of a polymer-supported inhibitor (PSI) and its inhibition performance for free-radical polymerization are reported for the first time. A special method has been devised to synthesize PSI with pure hydroquinone (HQ) groups anchored onto the polymer surface. A thin HQ/acetone (AC) solution is sandwiched between two polymer films. Under ultraviolet irradiation, AC as an photoinitiator quickly and effectively grafts HQ onto the polymer surface. For potential applications, PSI has been used to inhibit the thermal polymerization of styrene and methyl methacrylate. The corresponding inhibition performance has been investigated through the measurement of the induction period with the dilatometer method. With the same absolute amount, the maximum inhibition ability of PSI approaches half that of a free inhibitor. Increasing the dispersion degree of PSI is favorable for the enhancement of inhibition ability.

    18. A new high-throughput approach to measure copolymerization reactivity ratios using real-time FTIR monitoring (pages 4084–4100)

      Sohel Shaikh, Judit E. Puskas and Gabor Kaszas

      Article first published online: 12 JUL 2004 | DOI: 10.1002/pola.20244

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      Real-time Fourier transform infrared (FTIR) was used to monitor monomer disappearance in isobutylene/isoprene (IB/IP) copolymerization in situ, utilizing a fiberoptic probe. The polymerization was carried out in a mixed solvent system (hexane/methyl chloride) at −80 °C. Reactivity ratios were determined using linear and nonlinear methods. The IB/IP system was found to exhibit close to ideal behavior. It is demonstrated that reactivity ratios can be determined from a single experiment using a combination of the Kelen-Tüdös method and the van Herk nonlinear least square (NLLS) algorithm.