Journal of Polymer Science Part A: Polymer Chemistry

Cover image for Vol. 46 Issue 18

15 September 2008

Volume 46, Issue 18

Pages 5977–6364

  1. Articles

    1. Top of page
    2. Articles
    3. Article
    4. Rapid Communication
    5. Erratum
    1. Molecularly defined (L)-lactic acid oligomers and polymers: Synthesis and characterization (pages 5977–5990)

      Kenichi Takizawa, Hunaid Nulwala, Jerry Hu, Kohji Yoshinaga and Craig J. Hawker

      Version of Record online: 11 AUG 2008 | DOI: 10.1002/pola.22944

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      The synthesis of (L)-lactide oligomers from dimer to 64mer via an exponential growth strategy is described.

    2. Synthesis and characterization of sulfonated block copolymers by atom transfer radical polymerization (pages 5991–5998)

      Kyung-Youl Baek

      Version of Record online: 11 AUG 2008 | DOI: 10.1002/pola.22568

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      Well-defined sulfonated polystyrene and block copolymers with n-butyl acrylate (nBA) were prepared by deprotecting the neopentyl groups of poly(neopentyl p-styrene sulfonate) (PNSS) precursors via simple thermolysis at 150 °C, where the precursors of PNSS and PNSS-block-PnBA were synthesized by CuBr catalyzed living radical polymerization. (PNSS: MWD < 1.12; PNSS-block-PnBA: MWD < 1.29). This simple heating process gave 100% sulfonic acid groups to a polystyrene backbone in solid state, which was confirmed by 1H NMR and FTIR analysis.

    3. Synthesis, characterization, and properties of copolymer of acrylamide and complex pseudorotaxane monomer consisting of cucurbit[6]uril with butyl ammonium methacrylate (pages 5999–6008)

      Xiaoling Huang, Yebang Tan, Yuexia Wang, Hui Yang, Jie Cao and Yuju Che

      Version of Record online: 11 AUG 2008 | DOI: 10.1002/pola.22897

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      The novel copolymers (PAM/BAMACB) of acrylamide (AM) with complex pseudorotaxane monomer (BAMACB) of butyl ammonium methacrylate (BAMA) and cucurbit[6]uril (CB[6]) were prepared via free-radical polymerization. This type of polypseudorotaxane copolymers has unusual thermal and solution properties. The enhanced rigidity and bulky steric hindrance of BAMACB side chain can lead to the increase of the glass transition temperature of the copolymer PAM/BAMACB. The solution behaviors of PAM/BAMACB were unusual in aqueous solution or NaCl solutions. In aqueous solution, intermolecular aggregation is dominant, while transition between the intrachain and interchain association appear in 0.1 mol/ L NaCl solutions

    4. Manganese(III) acetate-catalyzed synthesis of polyguaiacol (pages 6009–6015)

      Sangpill Hwang, Yong-Woo Lee, Chang-Ha Lee and Ik-Sung Ahn

      Version of Record online: 11 AUG 2008 | DOI: 10.1002/pola.22902

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      Polyguaiacol was synthesized using manganese(III) acetate in aqueous solutions of water–miscible organic solvents such as acetonitrile, 1,4-dioxane, and methanol. The yield and the average molecular weight of polyguaiacol were affected by the organic solvent, which was explained using difference UV absorption spectroscopy. The formation of guaiacol clusters free of the direct contact with water molecules is believed to be necessary for the efficient formation of guaiacol radicals and the radical coupling leading to the synthesis of polyguaiacol. 1H NMR analysis revealed that the major structural units of polyguaiacol were those produced from the guaiacol oxidation where water molecules were not involved. [Color figure can be viewed in the online issue, which is available at www.interscience.wiley.com.]

    5. 9-Bromoanthracene photodimers as initiators in controlled radical polymerization: Silane radical atom abstraction coupled with nitroxide mediated polymerization (pages 6016–6022)

      Sona Thakur, Jenell R. Smith, Eric S. Tillman, Nicole A. Cohen and Nathan D. Contrella

      Version of Record online: 11 AUG 2008 | DOI: 10.1002/pola.22903

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      Silane radical atom abstraction (SRAA) is used to create initiating bridgehead radicals on photodimers of 9-bromoanthracene in the presence of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO). This reaction sequence, SRAA coupled with nitroxide mediated polymerization (NMP), generates polymers possessing partial anthracene end-labeling (∼ 25%), consistent with thermolysis of the anthracene photodimer and competition between initiation from the bridgehead photodimer radical and silane-based radical.

    6. Branched polystyrene with abundant pendant vinyl functional groups from asymmetric divinyl monomer (pages 6023–6034)

      Zhong-Min Dong, Xiao-Hui Liu, Ying Lin and Yue-Sheng Li

      Version of Record online: 11 AUG 2008 | DOI: 10.1002/pola.22913

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      Branched polystyrenes with abundant pendant vinyl functional groups were prepared via radical polymerization of an asymmetric divinyl monomer, which possesses a higher reactive styryl and a lower reactive butenyl. Employing a fast reversible addition fragmentation chain transfer (RAFT) equilibrium, the concentration of active propagation chains was remained at a low value and thus cross-linking did not occur until a high level of monomer conversion. The evolution of branched structure has been confirmed by a triple detection size exclusion chromatography (TRI-SEC) and NMR technique. Furthermore, the double bonds in the side chains were successfully performed the chemical modification reactions.

    7. A hybrid-type, chiral π-conjugated polymer wrapped with polyhedral oligomeric silsesquioxanes (pages 6035–6040)

      Junpei Miyake and Yoshiki Chujo

      Version of Record online: 11 AUG 2008 | DOI: 10.1002/pola.22914

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      A novel hybrid-type chiral π-conjugated polymer with polyhedral oligomeric silsesquioxanes (POSS) units was prepared. The investigation of the CD spectra indicates that the main chain chirality of the conjugated polymer systems leads to the observed strong Cotton effects. The thermal stability of POSS-modified polymer was extremely high compared with that of polymer without POSS unit due to the siliceous bulky POSS segments on the side chains. The incorporation of POSS units into polymer inhibited interchain interaction, which improves fluorescence quantum yield (ΦF) in dilute CHCl3 solution.

    8. Nylon 610/functionalized multiwalled carbon nanotube composite prepared from in-situ interfacial polymerization (pages 6041–6050)

      Jae-Yong Jeong, Hwa-Jeong Lee, Sang-Wook Kang, Loon-Seng Tan and Jong-Beom Baek

      Version of Record online: 11 AUG 2008 | DOI: 10.1002/pola.22916

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      In order to improve chemical affinity of pristine multi-walled carbon nanotubes (PMWNTs), they were functionalized with 4-chlorobenzoic acid in a mildly acidic medium to afford 4-chlorobenzoyl-functionalized multiwalled carbon nanotubes (FMWCNTs). F-MWCNTs were soluble in carbon tetrachloride. In-situ interfacial polymerization between sebacoyl chloride and F-MWNT in carbon tetrachloride and 1,6-hexamethylenediamine (HMDA) in water was carried out to afford nylon 610/FMWNT nanocomposite. F-MWNTs were distinctively better dispersed into the nylon 610 matrix.

    9. Random terpolymers for electroluminescent devices: Synthesis and characterization of new cyano-containing poly(fluorenylene-vinylene)s (pages 6051–6063)

      Roberto Grisorio, Claudia Piliego, Paola Fini, Pinalysa Cosma, Piero Mastrorilli, Giuseppe Gigli, Gian Paolo Suranna and Cosimo Francesco Nobile

      Version of Record online: 11 AUG 2008 | DOI: 10.1002/pola.22917

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      New random poly(2,7-fluorenylene-vinylene)s were prepared by a Suzuki-Heck cascade polymerization reaction. The polymers embodied 1-cyano-2,5-phenylene as electron-withdrawing unit (CN-PFV1) and 1,4-dioctyloxy-2,5-phenylene (CN-PFV2) or 3,6-N-octylcarbazolylene (CN-PFV3) as electron-donating groups. By combining CV data and optical band gap, a high electron affinity (2.96–3.21 eV) was revealed. The random terpolymers showed an efficient electroluminescence in the yellow-green region with luminances of 255–1403 cd/m2 and current efficiencies up to 0.13 Cd/A.

    10. Copolymerization behavior of titanium imidazolin-2-iminato complexes (pages 6064–6070)

      Simon H. Stelzig, Matthias Tamm and Robert M. Waymouth

      Version of Record online: 11 AUG 2008 | DOI: 10.1002/pola.22918

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      Monocyclopentadienyl titanium imidazolin-2-iminato complexes [Cp'Ti(L)X2] 1a (Cp' = cyclopentadienyl, L = 1,3-di-tert-butylimidazolin-2-imide, X = Cl) are active catalysts for the copolymerization of ethylene and 1-hexene. Activation with methylaluminoxane resulted in bimodal molecular weight distributions, but activation of the dialkyl 1b (X = CH3) with [Ph3C] [B(C6F5)4] or B(C6F5)3 yielded monomodal ethylene/hexene copolymers with narrow molecular weight distributions.

    11. Electrospray ionization mass spectrometric study of end-groups in peroxydicarbonate-initiated radical polymerization (pages 6071–6081)

      Michael Buback, Holm Frauendorf, Olaf Janssen and Philipp Vana

      Version of Record online: 11 AUG 2008 | DOI: 10.1002/pola.22919

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      Initiation by various peroxydicarbonates was studied by end-group analysis via electrospray ionization mass spectrometry (ESI-MS). Dialkyl peroxydicarbonates with linear alkyl groups essentially generate primary alkoxy carbonyloxyl radicals as initiating species. With di-2-ethylhexyl peroxydicarbonate, in addition to the 2-ethylhexoxy carbonyloxyl end-group, significant amounts of a second type of end-group are observed. The latter species results most likely from a radical species produced by decarboxylation of the primary carbonyloxyl radical via a concerted mechanism involving a 1,5-hydrogen shift reaction.

    12. Oligopeptide-based amide functional initiators for ATRP (pages 6082–6090)

      Dave J. Adams and Iain Young

      Version of Record online: 12 AUG 2008 | DOI: 10.1002/pola.22920

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      Under the appropriate conditions, a small family of oligo(phenylalanine)-based initiators can be used successfully to initiate the polymerization of methacrylic monomers by ATRP, generating new peptide–polymer conjugates. However, the use of the peptidic amide-based initiators results in polymers which have a higher molecular weight than expected and a significantly higher polydispersity than those prepared from ester-based initiators.

    13. Carboxylic acid-containing benzoxazines as efficient catalysts in the thermal polymerization of benzoxazines (pages 6091–6101)

      R. Andreu, J. A. Reina and J. C. Ronda

      Version of Record online: 12 AUG 2008 | DOI: 10.1002/pola.22921

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      Several mixtures of 3-phenyl-3,4-dihydro-2H-1,3-benzoxazine and three benzoxazine derivatives containing carboxylic groups were analyzed by differential scanning calorimetry to evaluate their autocatalytic thermal polymerization behavior. In this way, the polymerization temperature was found to decrease by as much as 100 °C in some cases. The existence of decarboxylation processes at high temperatures has been established by FTIR-ATR and related to the increase in thermal stability observed by TGA in some cases. A relationship between the presence of carboxylic groups in the resulting materials and their flame retardancy behavior has also been established.

    14. Asymmetric, regio- and stereo-selective alternating copolymerization of CO2 and propylene oxide catalyzed by chiral chromium Salan complexes (pages 6102–6113)

      Bo Li, Guang-Peng Wu, Wei-Min Ren, Yi-Ming Wang, Dun-Yan Rao and Xiao-Bing Lu

      Version of Record online: 12 AUG 2008 | DOI: 10.1002/pola.22922

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      Chiral chromium Salan complexes in conjunction with an ionic quaternary ammonium salt can efficiently catalyze the copolymerization of CO2 with racemic propylene oxide at mild conditions to selectively afford completely alternating poly(propylene carbonate) with ∼ 95% head-to-tail linkages and moderate enantioselectivity. These new catalyst systems predominantly exceed the previously much-studied SalenCr(III)X systems in catalytic activity, polymer enantioselectivity, and stereochemistry control. [Color figure can be viewed in the online issue, which is available at www.interscience.wiley.com.]

    15. A kinetic Monte Carlo study on the nucleation mechanisms of oil-soluble initiators in the miniemulsion polymerization of styrene (pages 6114–6128)

      Jonathan A. Rawlston, Juchen Guo, F. Joseph Schork and Martha A. Grover

      Version of Record online: 12 AUG 2008 | DOI: 10.1002/pola.22923

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      When using oil-soluble initiators in styrene miniemulsion polymerization, desorption of radicals is shown to be sometimes necessary to best describe the experimental molecular weight and conversion rate using kinetic Monte Carlo simulations. Possible chain-stopping mechanisms shown are simple termination (i), termination by initiator dissociation (ii), chain transfer to monomer (iii), and termination by absorption (iv). At a temperature of 75 °C, simple termination is shown to dominate the molecular weight distribution. When the initiator concentration is decreased and the temperature is decreased to 50 °C, chain transfer, most likely to occur after desorption, is shown to dominate.

    16. Living cationic polymerization of amide-functional vinyl ethers: Specific properties of SnCl4-based initiating system (pages 6129–6141)

      Motomasa Yonezumi, Satoshi Okumoto, Shokyoku Kanaoka and Sadahito Aoshima

      Version of Record online: 12 AUG 2008 | DOI: 10.1002/pola.22924

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      A Lewis acid/base initiating system successfully induced living cationic copolymerization of ever formidable monomers, amide-functional vinyl ethers. A key to smooth polymerization is careful selection of both a Lewis acid and an amide substituent. For example, living copolymerization of an amide monomer with isobutyl vinyl ether was achieved using SnCl4 in dichloromethane with ethyl acetate at 0 °C (Mw/Mn ≤ 1.2), whereas no polymer was obtained with EtAlCl2. The SnCl4 initiating system was also effective for the living cationic polymerization of various polar functional vinyl ethers, which have been difficult to polymerize with a conventional Al-based initiating system.

    17. Synthesis and characterization of double thermo-responsive block copolymer consisting N-isopropylacrylamide by atom transfer radical polymerization (pages 6142–6150)

      Youhei Kotsuchibashi, Yumi Kuboshima, Kazuya Yamamoto and Takao Aoyagi

      Version of Record online: 12 AUG 2008 | DOI: 10.1002/pola.22925

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      In this study we synthesized block copolymers consisting of poly(N-isopropylacrylamide) (NIPAAm)-b-poly(NIPAAm-co-N-(hydroxymethyl)acrylamide(HMAAm)) by atom transfer radical polymerization. The block copolymers exhibited reversible double thermo-responsive phase transition of polyNlPAAm and poly(NIPAAm-co-HMAAm) segments in the aqueous solution which were estimated by transmittance measurements. Lower cloud point indicate the polyNIPAAm segment and higher one shows poly(NIPAAm-co-HMAAm) segment. We expected micelle-like conformation of block copolymers comprising the core of polyNIPAAm segment and poly(NIPAAm-co-HMAAm) segment as the shell in the temperature range between two cloud points.

    18. Thermosensitive gradient copolymers by living cationic polymerization: Semibatch precision synthesis and stepwise dehydration-induced micellization and physical gelation (pages 6151–6164)

      Ken-Ichi Seno, Itsuko Tsujimoto, Takunobu Kikuchi, Shokyoku Kanaoka and Sadahito Aoshima

      Version of Record online: 12 AUG 2008 | DOI: 10.1002/pola.22926

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      Thermosensitive forced binary gradient copolymers of vinyl ethers with various sequence distributions were synthesized using a semibatch reaction method via base-stabilized living cationic polymerization. This article concerns gradient copolymers of 2-ethoxyethyl vinyl ether and 2-methoxyethyl vinyl ether with various sequence distributions. The resulting copolymers displayed properties of multisegmented copolymers upon heating their aqueous solutions. The copolymers underwent thermally induced association (micellization) above a critical temperature. Interestingly, the obtained micelles decreased monotonously in size with further increasing solution temperature. This is attributed to stepwise dehydration of a gradient copolymer along the chain. [Color figure can be viewed in the online issue, which is available at www.interscience.wiley.com.]

    19. Preparation and characterization of porous polymeric microspheres obtained from multifunctional methacrylate monomers (pages 6165–6174)

      Marta Grochowicz, Andrzej Bartnicki and Barbara Gawdzik

      Version of Record online: 12 AUG 2008 | DOI: 10.1002/pola.22927

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      New methacrylate monomer 2-hydroxy-3-methacryloyloxypropoxybenzene was applied for the synthesis of porous microspheres. It was copolymerized with trimethylolpropane trimethacrylate in the presence of pore forming diluents. AFM micrograph of the MPH-TRIM beads obtained via suspension-emulsion polymerization.

    20. Synthesis and characterization of fluorene-based low-band gap copolymers containing propylenedioxythiophene and benzothiadiazole derivatives for bulk heterojunction photovoltaic cell applications (pages 6175–6184)

      Jin Su Park, Tae In Ryu, Myungkwan Song, Kyung-Jin Yoon, Myung Jin Lee, In Ae Shin, Gi-Dong Lee, Jae Wook Lee, Yeong-Soon Gal and Sung-Ho Jin

      Version of Record online: 12 AUG 2008 | DOI: 10.1002/pola.22928

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      A noble series of soluble π-conjugated statistical copolymers, poly[(9,9-dioctylfluorene)-alt-(4,7-bis(3′,3′-dihepyl-3,4-propylenedioxythienyl)-2,1,3-benzothiadiazole)] (PFO-PTBT), was synthesized by palladium catalyzed Suzuki polymerization for use in bulk heterojunction photovoltaic cells. Bulk heterojunction photovoltaic cells with an ITO/PEDOT/PFO-PTBT:PCBM/LiF/Al configuration were fabricated, and the maximum power conversion efficiency (PCE) of 0.50 % (Voc = 0.66 V, FF = 0.29) was achieved with PFO-PTBT (6.5:3.5).

    21. A novel dispersant for preparation of high loading and photosensitive carbon black dispersion (pages 6185–6197)

      Kuo-Huai Kuo, Yu-Hsiang Peng, Wen-Yen Chiu and Trong-Ming Don

      Version of Record online: 12 AUG 2008 | DOI: 10.1002/pola.22929

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      A new CB dispersant, P(SEH)-b-P(SEHD)C[DOUBLE BOND]C, was prepared by the reaction between isocyanate group of H-I and hydroxyl group of P(SEH)-b-P(SEHD). P(SEH)-b-P(SEHD)C[DOUBLE BOND]C could be effectively adsorbed onto the surface of CB by the interaction between tertiary amine group of dispersant and carboxylic acid group on CB surface during ball-milling process and a high loading of CB dispersion was therefore prepared. In addition, P(SEH)-b-P(SEHD)C[DOUBLE BOND]C also had methacrylate double bond side group exhibiting UV-curable property. This CB dispersant can be applied in liquid crystal display industry, optoelectronic industry, and automobile industry.

    22. Synthesis and characterization of fluorescence end-labeled polystyrene via reversible addition-fragmentation chain transfer (RAFT) polymerization (pages 6198–6205)

      Di Zhou, Xiulin Zhu, Jian Zhu and Zhenping Cheng

      Version of Record online: 12 AUG 2008 | DOI: 10.1002/pola.22930

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      The steady-state and the time-resolved fluorescence techniques had been used to study the fluorescence behaviors of dithiocarbamate resulting heteroaromatic group end-labelled PS. The fluorescence of PS in solid powder can not be monitored; however they exhibited structured absorptions and emissions in solvent DMF and the fluorescence lifetimes of PS had no obvious change with molecular weights increase, which suggested that the polymer chains was possibly stretched adequately in DMF, i.e., the fluorescence end group was exposed into solvent molecules and little quenching of excited state occurred upon incorporation into polymer chain. [Color figure can be viewed in the online issue, which is available at www.interscience.wiley.com.]

    23. Core-shell type dually fluorescent polymer nanoparticles for ratiometric pH-sensing (pages 6206–6213)

      Emmanuel Allard and Chantal Larpent

      Version of Record online: 12 AUG 2008 | DOI: 10.1002/pola.22931

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      Dual fluorescent sensing particles are readily obtained using an all water-based facile and versatile synthetic procedure by covalent attachment of a pH sensitive fluorescent dye (FITC) to the surface of amine-functionalized cross-linked polystyrene-based nanoparticles (NPs) followed by entrapment of a hydrophobic insensitive fluorescent dye (diphenylanthracene) within the NPs core by soaking. These ultrafine nanoparticles are efficient reversible and robust ratiometric pH-sensors in the pH 4-8 range. The “core-shell” type structure maximizes the interactions of the sensing dye with the analyte while protecting the reference dye. [Color figure can be viewed in the online issue, which is available at www.interscience.wiley.com.]

    24. Thermal recordable novel cholesteric liquid crystalline polyacrylates containing various chiral moieties (pages 6214–6228)

      Jui-Hsiang Liu, Hsien-Jung Hung, Po-Chih Yang and Kai-Hsin Tien

      Version of Record online: 12 AUG 2008 | DOI: 10.1002/pola.22932

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      Sample films synthesized in this investigation patterned at various mesophase temperatures by contact with a flat hot or cool plate. After heat treatment, the polymer films were quenched to room temperature to fix the molecular arrangement and patterns. We have provided straightforward experimental evidence showing the synthesis of thermal recordable novel cholesteric liquid crystalline polyacrylates containing various chiral moieties. [Color figure can be viewed in the online issue, which is available at www.interscience.wiley.com.]

    25. Poly(hydroxyisobutyrate) by ring-opening polymerizations of 5,5-dimethyl-1,3,2-dioxithiolan-4-one-2-oxide (pages 6229–6237)

      Hans R. Kricheldorf, Nino Lomadze and Gert Schwarz

      Version of Record online: 12 AUG 2008 | DOI: 10.1002/pola.22933

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      Crystalline poly(hydroxyisobutyrate) was prepared by thermally induced, pyridine-catalyzed, and alcohol-initiated polymerizations. By thermal polymerization almost exclusively cycles were formed, most likely via a zwitterionic mechanism.

    26. Synthesis and characterization of hyperbranched polymers with increased chemical versatility for imprint lithographic resists (pages 6238–6254)

      Anzar Khan, Michael Malkoch, Martha F. Montague and Craig J. Hawker

      Version of Record online: 13 AUG 2008 | DOI: 10.1002/pola.22934

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      Hyperbranched Polymers were prepared from a variety of mono- and di-functional monomers and used in the development of novel UV imprint lithography (UV-1L) resists. The unique physical and chemical properties of these hyperbranched materials significantly increase the range of molecular systems that could be imprinted.

    27. Oxidative degradation of poly(isophthaloylhydrazine-1,2-diyl)s (pages 6255–6262)

      Nobuhiro Kihara, Yusuke Iino and Tatsuya Misawa

      Version of Record online: 13 AUG 2008 | DOI: 10.1002/pola.22935

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      Although poly(diacylhydrazine) is thermally stable below 300 °C in air, they rapidly decomposed on treatment with an oxidant such as sodium hypochlorite solution to quantitatively obtain the corresponding carboxylic acid and nitrogen.

    28. Poly(N,N-diethylacrylamide) microspheres by dispersion polymerization (pages 6263–6271)

      Daniela ŠponarovÁ and Daniel Horák

      Version of Record online: 13 AUG 2008 | DOI: 10.1002/pola.22936

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      SEM of poly(N,N-diethylacrylamide) microspheres crosslinked with 10 wt % of N,N′-methylenebisacrylamide. The microspheres were obtained by aqueous dispersion polymerization. Their size was controlled in the range 30–300 nm. Depending on the degree of crosslinking, a lower critical solution temperature behavior has been observed between 25 and 30 °C with a phase transition changing over a broader temperature range.

    29. Syntheses and characterization of physically crosslinked hydrogels from dithiocarbamate-derived polyurethane macroiniferter (pages 6272–6284)

      Alpesh Patel and Kibret Mequanint

      Version of Record online: 13 AUG 2008 | DOI: 10.1002/pola.22937

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      A novel dithiocarbamate (DC) based polyurethane macroiniferter (PUMI) was synthesized and used to prepare physically crosslinked polyurethane-block poly(acrylamide) (PU-b-PAAm) and polyurethaneblock- poly(vinyl pyrrolidone) (PU-b-PVP) hydrogels. [Color figure can be viewed in the online issue, which is available at www.interscience.wiley.com.]

    30. Poly(caprolactone) containing highly branched segmented poly(ester urethane)s via A2 with oligomeric B3 polymerization (pages 6285–6295)

      Serkan Unal, Gozde Ozturk, Kristin Sisson and Timothy E. Long

      Version of Record online: 13 AUG 2008 | DOI: 10.1002/pola.22938

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      Polymerization of A2 and oligomeric B3 type monomers was utilized to synthesize highly branched segmented poly(ester urethane)s and covalently crosslinked networks. Isocyanate functional butanediol-based A2 hard segment was reacted with poly(caprolactone) based oligomeric trifunctional (B3) soft segment. Mechanical and thermal properties were characterized using DMA, DSC, and tensile testing. Linear poly(ester urethane)s exhibited higher tensile strengths and Young's modulus compared to branched analogs due to presence of PCL crystalline phase. Highly branched hydroxyl terminated poly(ester urethane)s were reacted further with a low molar mass diisocyanate to form crosslinked networks. Crosslinked poly(ester urethane) networks exhibited higher tensile strengths than linear analogues.

    31. A simple approach toward low-dielectric polyimide nanocomposites: Blending the polyimide precursor with a fluorinated polyhedral oligomeric silsesquioxane (pages 6296–6304)

      Yun-Sheng Ye, Ying-Chieh Yen, Wen-Yi Chen, Chih-Chia Cheng and Feng-Chih Chang

      Version of Record online: 13 AUG 2008 | DOI: 10.1002/pola.22939

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      This paper presents a simple and efficient method for preparing polyimide nanocomposites with low dielectric constants and good thermal properties: simply blending the polyimide precursor with the fluorine-containing POSS derivative OF. [Color figure can be viewed in the online issue, which is available at www.interscience.wiley.com.]

    32. Synthesis, properties, and field effect transistor characteristics of new thiophene-[1,2,5]thiadiazolo[3,4-g]quinoxaline-thiophene-based conjugated polymers (pages 6305–6316)

      Kai-Fang Cheng, Chu-Chen Chueh, Chia-Hung Lin and Wen-Chang Chen

      Version of Record online: 13 AUG 2008 | DOI: 10.1002/pola.22942

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      Synthesis, properties, and field-effect transistor (FET) characteristics of bis(4-hexylthiophen-2-yl)-6,7-diheptyl-[1,2,5]thiadiazolo[3,4-g]quinoxaline (BTHTQ)-based donor–acceptor-conjugated polymers were explored. The optical band gaps of PBTHTQ, PTTHTQ, PFBTHTQ, and PPBTHTP were 1.31, 1.05, 1.40, and 1.43 eV, respectively. It suggested the significance of intramolecular charge transfer between the donor and TQ moiety. The estimated FET hole mobilities of PTTHTQ using CHCl3 and chlorobenzene-processing solvents were 8.5 × 10−4 and 3.8 × 10−3 cm2 V−1 s−1, respectively. The higher hole mobility of PTTHTQ than the other copolymers was attributed from its smaller band gap or ordered morphology [wormlike (chloroform) or needlelike (chlorobenzene)].

    33. Irreversible temperature-responsive formation of high-strength hydrogel from an enantiomeric mixture of starburst triblock copolymers consisting of 8-arm PEG and PLLA or PDLA (pages 6317–6332)

      Koji Nagahama, Kanae Fujiura, Shunsuke Enami, Tatsuro Ouchi and Yuichi Ohya

      Version of Record online: 13 AUG 2008 | DOI: 10.1002/pola.22943

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      Phase diagram of equimolar mixture of aqueous solutions of starburst 8-arm PEG-b-PLLA-b-PEG and 8-arm PEG-b-PDLA-b-PEG (Stri-Mix), and photographs and polarized optical micrographs of Stri-Mix aqueous solution (10 wt %) above and below the phase transition temperature: top, 37 °C; bottom, 20 °C. [Color figure can be viewed in the online issue, which is available at www.interscience.wiley.com.]

    34. β-Hydrogen transfer from poly(methyl methacrylate) propagating radicals to the nitroxide SG1: Analysis of the chain-end and determination of the rate constant (pages 6333–6345)

      Charlotte Dire, Joël Belleney, Julien Nicolas, Denis Bertin, Stéphanie Magnet and Bernadette Charleux

      Version of Record online: 13 AUG 2008 | DOI: 10.1002/pola.22945

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      Methyl methacrylate was polymerized in bulk at 70 °C in the presence of increasing amounts of free SG1. Low monomer conversions were reached, indicating a loss in radical activity due to irreversible homotermination between the propagating radicals and to β-hydrogen transfer from a propagating radical to free nitroxide. β-hydrogen transfer was the major chain-stopping event in the presence of large excess of free SG1, whereas the two termination modes coexisted in the presence of lower excess. The rate constant of β-hydrogen transfer, kβHtr, was estimated to be 1.69 × 103 L mol−1 s−1 at 70 °C and simulations via PREDICI allowed the system to be fully understood. [Color figure can be viewed in the online issue, which is available at www.interscience.wiley.com.]

  2. Article

    1. Top of page
    2. Articles
    3. Article
    4. Rapid Communication
    5. Erratum
    1. Synthesis of linear and 4-arm star block copolymers of poly(methyl acrylate-b-solketal acrylate) by SET-LRP at 25 °C (pages 6346–6357)

      Michael R. Whittaker, Carl N. Urbani and Michael J. Monteiro

      Version of Record online: 13 AUG 2008 | DOI: 10.1002/pola.22946

      Thumbnail image of graphical abstract

      The new SET-LRP was successfully used to produce well-defined linear and star homo- and diblock copolymers of PMA, PSA, and P(MA-b-GA)n (where n = 1 or 4). The kinetic data showed that all SET-LRP were first order and reached high conversions in a short period of time. The molecular weight distributions were well controlled and close to the theory. The linear and star block copolymers were then hydrolyzed to produce the biocompatible amphiphilic P(MA-b-GA)n, where the glycerol side-groups make the outer block hydrophilic. The TEM's showed that linear blocks formed classical core-shell micelles, and the star blocks formed vesicles. [Color figure can be viewed in the online issue, which is available at www.interscience.wiley.com.]

  3. Rapid Communication

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      Iron(III) chloride/R-Cl/tributylphosphine for metal-catalyzed living radical polymerization: A unique system with a higher oxidation state iron complex (pages 6358–6363)

      Kotaro Satoh, Hiroshi Aoshima and Masami Kamigaito

      Version of Record online: 13 AUG 2008 | DOI: 10.1002/pola.22941

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      Iron(III) chloride (FeCl3), a higher oxidation state iron species, was employed for the metal-catalyzed living radical polymerization of styrene in the presence of tributylphosphine and a chloride initiator without any added reducing agents or radical initiators. The polymerization smoothly proceeded in toluene at 100 °C to produce polymers with controlled molecular weights and narrow molecular weight distributions (MWDs) (Mw/Mn = 1.1–1.2). The copolymerization of styrene and methyl methacrylate resulted in the simultaneous consumption of both monomers to give copolymers with controlled molecular weights and narrow MWDs, indicating that the FeCl3-catalyzed polymerization proceeded via a radical mechanism.

  4. Erratum

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      Synthesis of methacrylate derivatives oligomers by dithiobenzoate-RAFT-mediated polymerization (page 6364)

      Elham Hosseini Nejad, Patrice Castignolles, Robert G. Gilbert and Yohann Guillaneuf

      Version of Record online: 13 AUG 2008 | DOI: 10.1002/pola.22981

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