Journal of Polymer Science Part A: Polymer Chemistry

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

15 January 2008

Volume 46, Issue 2

Pages 383–752

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      Dendritic macromers for hydrogel formation: Tailored materials for ophthalmic, orthopedic, and biotech applications (pages 383–400)

      Mark W. Grinstaff

      Article first published online: 5 DEC 2007 | DOI: 10.1002/pola.22525

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      A series of crosslinkable, biodegradable dendritic macromolecules are described for the preparation of hydrogels. The properties—mechanical, swelling, degradation, and so forth—of the hydrogels can be tuned by altering the composition, crosslinking chemistry, wt %, and generation number. These hydrogels have been used for repairing corneal wounds, for engineering cartilage tissue, and for screening molecular recognition events.

  2. Articles

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    1. Synthesis and self assembly of eosin functionalized amphiphilic block-random copolymers prepared by ring opening metathesis polymerization (pages 401–413)

      Martina Sandholzer, Gerhard Fritz-Popovski and Christian Slugovc

      Article first published online: 4 DEC 2007 | DOI: 10.1002/pola.22391

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      Herein we present the synthesis and characterization of amphiphilic block-random copolymers with a covalently incorporated pH-sensitive dye, namely eosin. The self assembly behavior of the block-random copolymers in MeOH and EtOH was studied by dynamic light scattering (DLS) and small angle X-ray scattering (SAXS). The influence of dye incorporation on the result of the self assembly process in methanol and ethanol was investigated and a subtle interplay of the nature of the selective solvent, the chain-length of the block copolymer, and the position of the dye within the polymer chain was established. [Color figure can be viewed in the online issue, which is available at www.interscience.wiley.com.]

    2. Synthesis, characterization, and properties of new thermally curable polyetheresters containing benzoxazine moieties in the main chain (pages 414–420)

      Baris Kiskan, Yusuf Yagci and Hatsuo Ishida

      Article first published online: 4 DEC 2007 | DOI: 10.1002/pola.22392

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      High molecular weight polyetheresters (PEE) containing thermally curable benzoxazine units in the main chain have been synthesized. Polycondensation of benzoxazine dietherdiol with adipoyl chloride and terephthaloyl dichloride in the presence of triethyl amine yields the corresponding polyetheresters with the molecular weights of 34.000 Da. Curing behavior of both the monomer and polymers has also been studied by differential scanning calorimetry (DSC). Flexible free standing transparent films of the PEEs are obtained by solvent casting from dichloromethane solution on Teflon plates. The films preserve shape, and to some extent, toughness after thermal curing between 140 and 220 °C. Thermal properties of the cured polymers are also investigated by thermogravimetric analysis (TGA).

    3. Synthesis of poly(ethyl acrylate) by single electron transfer-degenerative chain transfer living radical polymerization in water catalyzed by Na2S2O4 (pages 421–432)

      Jorge F. J. Coelho, Erica Y. Carvalho, Dina S. Marques, Anatoliy V. Popov, Virgil Percec, Pedro M. F. O. Gonçalves and M. H. Gil

      Article first published online: 4 DEC 2007 | DOI: 10.1002/pola.22393

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      Single-electron-transfer/degenerative-chain transfer mediated living radical polymerization (ET-DTLRP) of ethyl acrylate (EtA) initiated with iodoform (CH3) and catalyzed by sodium dithionite (Na2S2O4) in water at 35 °C produces a telechelic poly(EtA) chains that were successfully reinitiated in water. The structural analysis of this polymer were assessed and compared to the PEtA prepared by free radical polymerization at the same temperature.

    4. Synthesis of triblock copolymers from glycolysed poly(ethylene terephthalate) by living radical polymerization (pages 433–443)

      Gael Colomines, Belkacem Otazaghine, Cyrille Boyer, Sophie Monge and Jean-Jacques Robin

      Article first published online: 4 DEC 2007 | DOI: 10.1002/pola.22394

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      The present contribution deals with the synthesis of (polystyrene-stat-polyglycidyl methacrylate)-b-PETG-b-(polystyrene-stat-polyglycidyl methacrylate) using a glycolysate macroinitiator by living radical polymerization for the valorization of PET waste for application in resins for heat curable paints.

    5. Appreciable norbornene incorporation in the copolymerization of ethylene/norbornene using titanium catalysts containing trianionic N[CH2CH(Ph)O]33− ligands (pages 444–452)

      Padmanabhan Sudhakar

      Article first published online: 4 DEC 2007 | DOI: 10.1002/pola.22395

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      The change in the symmetry of the catalyst system invariably influences the polymerization behavior in terms of norbornene distribution in the copolymer produced. In the current analyses with the modified TREN systems, we have shown the effect of symmetry influence over the microstructure of the polymers obtained. The catalyst with C3 symmetry (1-TiCl) incorporates NBE to a greater extent (with NBE diad insertions) compared with that of the Cs analogue (2-TiCl). Thus we have demonstrated that both the monomer reactivities and the monomer sequence distributions could be tuned by a simple modification of the symmetry of the catalyst.

    6. Molecular design of efficient white-light-emitting fluorene-based copolymers by mixing singlet and triplet emission (pages 453–463)

      Yunhua Xu, Rong Guan, Jiaxing Jiang, Wei Yang, Hongyu Zhen, Junbiao Peng and Yong Cao

      Article first published online: 4 DEC 2007 | DOI: 10.1002/pola.22396

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      A new strategy to realize efficient white-light emission from copolymers with the fluorene segment as a blue emitter and the iridium complex as a red emitter has been proposed and demonstrated. The strategy to incorporate singlet green emitter to the polyfluorene backbone and to attach triplet red species to the side chain is promising for WPLEDs. [Color figure can be viewed in the online issue, which is available at www.interscience.wiley.com.]

    7. Pure white-light-emitting diodes from phosphorescent single polymer systems (pages 464–472)

      Po-I Lee, Steve Lien-Chung Hsu and Jung-Feng Lee

      Article first published online: 5 DEC 2007 | DOI: 10.1002/pola.22397

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      New white polymeric light-emitting diodes from phosphorescent single polymer systems have been developed using a blue-light-emitting fluorene monomer copolymerized with a red-light-emitting phosphorescent dye, and end-capped with a green-light-emission dye. By adjusting the molar ratio of the three components, we were able to balance the light color of the copolymers to obtain pure white light with Commission Internationale de l'Eclairage (CIE) coordinates of (0.33, 0.34).

    8. Specific stimuli-responsive antipolyelectrolyte swelling of amphiphilic gel based on methacryloxyethyl dimethyloctane ammonium bromide (pages 473–480)

      Ling Xu, Maolin Zhai, Ling Huang, Jing Peng, Jiuqiang Li and Genshuan Wei

      Article first published online: 4 DEC 2007 | DOI: 10.1002/pola.22398

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      An amphiphilic gel was synthesized from methacryloxyethyl dimethyloctane ammonium bromide (MODAB). PMODAB gels compose of particulate aggregation because of the microphase separation in pure water. The gels possess distinguished different swelling behaviors with those of polyelectrolyte hydrogel: (1) Showing antipolyelectrolyte behavior in aqueous solution of NaCl; (2) Gel expanded with increasing temperature and phase transition occurred at an upper critical solution temperature. The special swelling behavior of PMODAB gel is correlated to the hydrophobic interaction and ion-cluster formed between tetra-alkyl ammonium cation and Br, which lead to the special gel morphology and is affected by the composition and temperature of the surrounding solution.

    9. Monodispersed PEG-b-PSt nanoparticles prepared by atom transfer radical emulsion polymerization under microwave irradiation (pages 481–488)

      Zushun Xu, Xiaoxi Hu, Xiaoqin Li and Changfeng Yi

      Article first published online: 4 DEC 2007 | DOI: 10.1002/pola.22399

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      Monodipersed polymeric nanoparticles were prepared combining the characteristics of microwave irradiation and atom transfer radical emulsion polymerization. It was visible from the TEM image that the diameters of nanoparticles prepared by atom transfer radical emulsion polymerization under microwave irradiation were smaller than 50 nm and monodispersed. The diameters of nanoparticles calculated with TEM image and measured by PCS were 30.3 and 32.7 nm separately.

    10. Vinyl polymerization of norbornene by mono- and trinuclear nickel complexes with indanimine ligands (pages 489–500)

      Guangrong Tang, Yue-Jian Lin and Guo-Xin Jin

      Article first published online: 4 DEC 2007 | DOI: 10.1002/pola.22400

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      Mono- and Trinuclear Nickel Complexes with Indanimine Ligands have been synthesized and characterized. In the presence of MAO, these complexes can be used as the catalysts for the vinyl polymerization of norbornene with high activities. [Color figure can be viewed in the online issue, which is available at www.interscience.wiley.com.]

    11. Luminescence properties of soluble 2,2′,7,7′-Tetrakis(2-(9-hexyl-9H-carbazol-3-yl)-vinyl)-9,9′-spirobifluorene-labeled dendrimers: Photoluminescence and electroluminescence (pages 501–514)

      Hong Suk Kim, Min Ju Cho, Kyung Moon Jung, Young-Jun Yu, Young Woo Park, Jung-Il Jin and Dong Hoon Choi

      Article first published online: 4 DEC 2007 | DOI: 10.1002/pola.22401

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      New light emitting dendrimers were synthesized by reacting 3,5-bis-(3,5-bis-benzyloxy-benzyloxy)-benzoic acid or 3,5-bis-[3,5-bis-(3,5-bis-benzyloxy-benzyloxy)-benzyloxy]-benzoic acid with a carbazolyl vinyl spirobifluorene moiety. Photoluminescence studies of the dendrimer, 10 demonstrated that at the higher density of benzyloxy dendrons, the featureless vibronic transitions were improved, causing lesser excimer emission. The electroluminescence spectra of multilayered devices made using 10 predominantly exhibited blue emissions; similar emission was observed in the PL spectra of its thin film.

    12. Preparation of MEH-PPV/nanosized titania hybrids via in situ sol–gel reaction of titanium alkoxide: Optical property (pages 515–529)

      Hung-Jen Chen, Leeyih Wang and Wen-Yen Chiu

      Article first published online: 4 DEC 2007 | DOI: 10.1002/pola.22402

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      Homogenously dispersed organic (MEH-PPV)/inorganic (nanosized titania) hybrids were successfully synthesized. The key benefit of this preparation was that titanium isopropoxide interacted with both 2-chlorophenol and MEH-PPV, so that phase separation could be kept to a minimum with a suitable recipe. The morphology as well as optical properties of the MEH-PPV/TIP(titania) hybrid were examined. A redshift in the photoluminescence (PL) emission was observed in almost all the hybrids in the solution state, because of the aggregation of MEH-PPV. However, it was found that spinning destroyed the aggregation of MEH-PPV, resulting in a blueshift in the PL emission of the hybrid films.

    13. Copolymers of 4-(1-methyl-1-mesityl-3-cyclobutyl)-2-N-1, 3-thiazole-2-yl methacrylamide with 2-[(5-methylisoxazol-3-yl) amino]-2-oxo-ethyl methacrylate: Synthesis, characterization, monomer reactivity ratios and biological activity (pages 530–542)

      Ibrahim Erol and Ayşe Dedelioglu

      Article first published online: 4 DEC 2007 | DOI: 10.1002/pola.22403

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      The synthesis of new methacrylamide monomers (MCTMA) having pendant thiazole and cyclobutane ring moieties have been reported for the first time. The structure of monomer and its homopolymer was characterized by spectroscopic methods. Copolymers of this monomer with a new methacrylate monomers, IAOEMA having different copolymer compositions were prepared. The reactivity ratio values were derived from the FR and KT methods were in good agreement with each other. The biological activity and thermal stability of the polymers were investigated. The MCTMA monomer and its copolymers had good biological activity in comparison with standard drugs. The decomposition activation energies of the polymers were calculated with the Ozawa method.

    14. Equimolar “a2 + b4” polycondensations—Cyclic polyethers derived from 1,4-dicyanotetrafluorobenzene and various diphenols (pages 543–551)

      Hans R. Kricheldorf and Kirstin Bornhorst

      Article first published online: 6 DEC 2007 | DOI: 10.1002/pola.22404

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      In equimolar polycondensations of 1,4-dicyanotetrafluorobenzene with various diphenols, gelation is avoidable only at concentrations yielding cyclic polyethers. The remaining C[BOND]F groups are then available for nucleophilic substitution.

    15. Effect of molecular architecture and size of mesogen on phase behavior and photoactive properties of photoactive liquid crystalline hyperbranched polyester epoxies containing benzylidene moiety (pages 552–563)

      V. Srinivasa Rao and A. B. Samui

      Article first published online: 4 DEC 2007 | DOI: 10.1002/pola.22405

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      The effect of molecular architecture (linear and hyperbranched), size of mesogenic unit (cyclic and acyclic units) on the physicochemical, thermal, mesogenic, and photoactive properties of hyperbranched polymers were studied and compared. Intermolecular photo cycloaddition reaction was confirmed by NMR spectroscopy and photo viscosity measurement of UV irradiated polymer solutions. Photoactive liquid crystalline hyperbranched polymers containing acyclic alkanone moieties have shown rapid response to light. The change in the refractive index was found to be in the range 0.024–0.02. Substantial variation of refractive index indicates that this polymer could be used for optical recording. The present investigation throws light on designing structure of photoactive liquid crystalline hyperbranched polymers.

    16. Bottlebrush-shaped copolymers with cellulose diacetate backbone by a combination of ring opening polymerization and ATRP (pages 564–573)

      Petr Vlček, Miroslav Janata, Petra Látalová, Jiří Dybal, Milena Špírková and Luděk Toman

      Article first published online: 6 DEC 2007 | DOI: 10.1002/pola.22406

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      Cellulose diacetate (CDA), partly acylated with 2-bromoisobutyryl bromide and containing thus both the hydroxy and 2-bromoisobutyryl groups (BriB), was grafted in two steps. First, poly(ε-caprolactone) (CL) grafts were generated by ROP giving p(CDA-g-CL) copolymer. In the next step, this copolymer with anchored BriB groups was used for ATRP grafting of vinyl monomers (styrene, MMA, butyl acrylate) under CuCl catalysis, which led to densely grafted copolymer with chemically different grafts, e.g. p(CDA-g-CL-g-MMA). As the degree of functionalization was 0.5, the grafts in the final product should more or less alternate and their lengths can be controlled.

    17. Synthesis and self-assembly of amphiphilic dendronized conjugated polymers (pages 574–584)

      Xing Xiao, Yonggang Wu, Minghao Sun, Jianjun Zhou, Zhishan Bo, Lin Li and Chiming Chan

      Article first published online: 6 DEC 2007 | DOI: 10.1002/pola.22407

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      Two kinds of amphiphilic dendronized conjugated polymers, polyfluorene and poly(binaphthyl-alt-fluorene), were synthesized by Suzuki polycondensation of hydrophobic macromonomers with two nonpolar octyloxy chains and hydrophilic macromonomers with two polar oligo(ethylene oxide) chains. The different configurations in the conjugated main chains result in different supramolecular self-assembly morphologies.

    18. High-temperature catalysts for the production of α-olefins based on iron(II) and iron(III) tridentate bis(imino)pyridine complexes modified by nitrilo group (pages 585–611)

      Alex S. Ionkin, William J. Marshall, Douglas J. Adelman, Barbara Bobik Fones, Brian M. Fish, Matthew F. Schiffhauer, Paul D. Soper, Robert L. Waterland, Rupert E. Spence and Tuyu Xie

      Article first published online: 6 DEC 2007 | DOI: 10.1002/pola.22408

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      The complexes functionalized with para-nitrilo group tend to make α-olefins with higher Schultz–Flory K values and with the smaller amounts of insoluble α-olefins than corresponding complexes without para-nitrilo groups. However, the nitrilo complexes were found to be less productive.

    19. Preparation and cryogenic mechanical properties of epoxy resins modified by poly(ethersulfone) (pages 612–624)

      Guo Yang, Bin Zheng, Jiao-Ping Yang, Guan-Shui Xu and Shao-Yun Fu

      Article first published online: 6 DEC 2007 | DOI: 10.1002/pola.22409

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      A thermoplastic, poly(ethersulfone) (PES), was used to modify a bisphenol-F based epoxy resin cured with an aromatic diamine. The cryogenic mechanical behaviors of the unmodified and modified epoxy resins were studied at liquid nitrogen temperature (77 K) and compared with those at room temperature (RT). The impact strength at 77 K increased with the increase of the PES content and reached the maximum value for the 20 phr blend corresponding to the cocontinuous phase morphology followed by a rapid decrease for the 25 phr blend, which is similar to that at RT.

    20. Block copolymer preparation by atom transfer radical polymerization under emulsion conditions using a nanoprecipitation technique (pages 625–635)

      Delphine Chan-Seng, David A. Rider, Gérald Guérin and Michael K. Georges

      Article first published online: 6 DEC 2007 | DOI: 10.1002/pola.22410

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      Atom transfer radical polymerization (ATRP) of n-butyl acrylate under emulsion polymerization conditions was conducted. Emulsion particles were prepared using a nanoprecipitation technique in which an oligomer prepared under bulk conditions and dissolved in acetone is precipitated in an aqueous solution containing CuBr, BPMODA and Brij 98. Block copolymers of styrene, t-butyl acrylate and acrylic acid consisting of a short poly(n-butyl acrylate) block were prepared free of any contamination from the macroinitiator. The amphiphilic poly(n-butyl acrylate)-b-poly(acrylic acid) block copolymers were studied under bulk (thin films) and aqueous solution to evaluate their ability to self-assemble.

    21. Photocrosslinking in dichromated poly(acrylic acid) during hologram recording and comparison with dichromated poly(vinyl alcohol) (pages 636–642)

      Anne Barichard, Yaël Israëli and Agnès Rivaton

      Article first published online: 6 DEC 2007 | DOI: 10.1002/pola.22411

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      Irradiation of dichromated poly(acrylic acid) film under conditions representative of hologram formation provoked the increase of the hardness resulting from the formation of covalent bonds between the macromolecular chains. This photocrosslinking process is different from the one observed in dichromated poly(vinyl alcohol) proceeding through coordination bonds around chromium(V). This difference gives evidence for the specific role played by the [BOND]OH and [BOND]COOH functions.

    22. Crown-like macrocycle zinc complex derived from β-diketone ligand for the polymerization of rac-lactide (pages 643–649)

      Xuan Pang, Xuesi Chen, Xiuli Zhuang and Xiabin Jing

      Article first published online: 6 DEC 2007 | DOI: 10.1002/pola.22412

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      The new Schiff base zinc complex 2 was used as an initiator to polymerize rac-lactide in a controlled manner to give heterotactic enriched polylactide.

    23. Encapsulation and release by star-shaped block copolymers as unimolecular nanocontainers (pages 650–660)

      Dilek Kul, Lieven M. Van Renterghem, Michael A.R. Meier, Satu Strandman, Heikki Tenhu, Sevil S. YIlmaz, Ulrich S. Schubert and Filip E. Du Prez

      Article first published online: 6 DEC 2007 | DOI: 10.1002/pola.22413

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      The encapsulation of five-arm star-shaped PEO-b-PtBA block copolymers, prepared by ATRP using a five-arm star-shaped PEO-macroinitiator, and their release properties in acid environment have been followed by UV-spectroscopy and color changes, using the dye methyl orange as a hydrophilic guest molecule. [Color figure can be viewed in the online issue, which is available at www.interscience.wiley.com.]

    24. Synthesis of poly(ester amide)s with lateral groups from a bulk polycondensation reaction with formation of sodium chloride salts (pages 661–667)

      Montserrat Vera, Lourdes Franco and Jordi Puiggalí

      Article first published online: 6 DEC 2007 | DOI: 10.1002/pola.22414

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      Poly(ester amide)s with a regular sequence and derived from the ethyl ester of L-lysine, a dicarboxylic acid and glycolic acid can be easily synthesized by using a thermal polycondensation method based on the formation of metal halide salts as a driving force. No secondary reactions such as transesterification occur under the required polymerization conditions.

    25. Synthesis and supramolecular self-assembly of thermosensitive amphiphilic star copolymers based on a hyperbranched polyether core (pages 668–681)

      Haiyan Hong, Yiyong Mai, Yongfeng Zhou, Deyue Yan and Yan Chen

      Article first published online: 6 DEC 2007 | DOI: 10.1002/pola.22415

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      The work reported the synthesis and self-assembly of a novel thermosensitive amphiphilic star copolymer based on a hyperbranched polyether core. The copolymers can synchronously self-assemble into core–shell umimolecular micelles and large multimolecular micelles in water, and demonstrate a reversible thermosensitive phase transition with a LCST through a mechanism as shown in the figure. On heating, the large polymer micelles first shrunk in size due to the collapse of micelle corona, and then joined together to form even larger aggregates driven by the increasing intermicellar hydrophobic interaction. The potential of the thermosensitive star copolymer in controlled drug release is attractive.

    26. Synthesis of tetrazole-containing azo polymers with properties of photo-induced birefringence and surface-relief-gratings via RAFT polymerization (pages 682–691)

      Liping Yu, Zhengbiao Zhang, Xinrong Chen, Wei Zhang, Jianhong Wu, Zhenping Cheng, Jian Zhu and Xiulin Zhu

      Article first published online: 6 DEC 2007 | DOI: 10.1002/pola.22416

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      A novel optically active monomer, 6-{4-[4-(1-phenyl-1H-tetrazol-5-yloxy)-phenylazo]-phenoxy}-hexyl methacrylate (PTPPHMA) bearing tetrazole and azobenzol moieties, was synthesized and polymerized by reversible addition-fragmentation chain transfer (RAFT) polymerization. The photochemical interconversion between trans and cis isomers of polyPTPPHMA(PPTPPHMA) in N,N′-dimethyl formamide (DMF) solution was explored under irradiation of ultraviolet light. PPTPPHMA exhibited potential applications in the optical storage: a maximum birefringence of 0.1 and no significant change of the values of the birefringence after several cycles of writing/erasing/rewriting sequences. Meanwhile, the surface-relief-gratings (SRGs) were induced on the polymer films by interference of Kr+ laser beams at 413.1 nm with 35 mW·cm−2 intensity, the diffraction efficiencies from SRGs were measured to be in the range of 2.0–2.5%. [Color Figure can be viewed in the online issue, which is available at www.interscience.wiley.com.]

    27. Synthesis and thermal characterization of novel poly(tetramethyl-1,3-silphenylenesiloxane) derivative with phenol moiety in the main chain (pages 692–701)

      Yoshinori Niwa, Shigeki Kouno, Wakako Sayama and Nobukatsu Nemoto

      Article first published online: 6 DEC 2007 | DOI: 10.1002/pola.22417

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      Novel poly(tetramethyl-5-hydroxy-1,3-silphenylenesiloxane) (P1) was synthesized via deprotective hydrogenation of poly(tetramethyl-5-benzyloxy-1,3-silphenylenesiloxane) (Pre-P1) catalyzed by 10% palladium on charcoal as well as via direct polycondensation of 3,5-bis(dimethylhydroxysilyl)phenol (M2). The glass transition temperature (Tg) of P1 was 40 °C, which was much higher than that of poly(tetramethyl-1,3-silphenylenesiloxane). The temperature at 5% weight loss (Td5) of the obtained polymer was 393 °C, which was lower than that of poly(tetramethyl-1,3-silphenylenesiloxane), indicating that the phenol moieties decline the thermal stability; however, the obtained P1 would promise to be a new reactive poly(tetramethyl-1,3-silphenylenesiloxane) derivative with phenol moieties to develop new functional materials.

    28. Linear π-conjugated polymers containing 2,4,6-tris(thiophen-2-yl)-1,3,5-triazine unit: Synthesis and optical properties (pages 702–712)

      Li Zou, Yang Fu, Xiaobing Yan, Xingguo Chen and Jingui Qin

      Article first published online: 6 DEC 2007 | DOI: 10.1002/pola.22418

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      The simple synthetic routes for some linear π-conjugated polymers containing 2,4,6-tris-(2-thienyl)-1,3,5-triazine unit have been introduced. It is found that the fluorescence can be tunable with satisfied quantum yield through the linkage of 2,4,6-tris(thiophen-2-yl)-1,3,5-triazine unit with different aromatic ring. And the LUMO and HOMO levels of the polymers can also be adjustable via the main-chain structural modification.

    29. Syntheses, characterization, optical properties, and charge-transfer complexation study of fluorescent poly(aryl-ether-urea) dendrimers (pages 713–724)

      Mahalingam Vanjinathan and A. Sultan Nasar

      Article first published online: 6 DEC 2007 | DOI: 10.1002/pola.22419

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      First example of fluorescent aryl-ether-urea dendrimers up to third generation with amine end groups were prepared by convergent approach without need for protection/deprotection steps. A repetitive synthetic sequence of nucleophilic addition reaction between amine and regenerated isocyanate and reduction of nitro groups into amine are adopted for the synthesis of these dendrimers. These dendrimers was found to display fluorescence and forms charge-transfer complexes with electron acceptor molecules as evidenced by emission and absorption spectra respectively.

    30. Delaminated zeolite-catalysed synthesis of high-molecular weight polycarbosilane as a low shrinkage SiC precursor (pages 725–732)

      Chi Thanh Nguyen, Dong Pyo Kim and Suk Bong Hong

      Article first published online: 5 DEC 2007 | DOI: 10.1002/pola.22420

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      The figure shows the SEM side view images before and after pyrolysis under N2 at 1100 °C for 1 h of H-PCS(V) spin-coated films on Si (100) substrates. The SiC films obtained after pyrolysis showed no detectable pinholes or cracks. During the pyrolysis step, in general, severe shrinkage of preceramic films takes place as a result of thermal conversion of low density polymers to higher density ceramic phases accompanied by weight loss. In this figure, the SiC(V) film shows a shrinkage level of only 16% suggests that H-PCS(V), its preceramic polymer, is potentially useful for the fabrication of SiC structures with superior dimensional stability. Because of the higher molecular weight with narrow PDI than that of any other H-PCS samples, H-PCS(V) may produce a smaller amount of volatile species during pyrolysis, yielding a smaller loss in weight.

    31. Cationic ring-opening copolymerization behavior of trioxane and seven-membered cyclic carbonate (pages 733–739)

      Daisuke Nagai, Kensuke Yokota, Takuma Ogawa, Bungo Ochiai and Takeshi Endo

      Article first published online: 5 DEC 2007 | DOI: 10.1002/pola.22421

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      Cationic ring-opening copolymerization behavior of trioxane (TOX) and a seven-membered cyclic carbonate, 1,3-dioxepan-2-one (7CC) is described. When TOX and 7CC were cationically copolymerized under various feed ratios using trifluoromethane sulfonic acid (TfOH) as an initiator in nitrobenzene at 30 °C, 7CC was consumed faster than TOX and the decarboxylation was accompanied to afford the corresponding polyacetal–polycarbonate type copolymers containing poly(oxytetramethylene) units. The copolymer composition could be controlled by the feed ratio of 7CC, whose increase resulted in the high copolymer composition of the 7CC unit. The solubility of the copolymers increased as the increase of the 7CC content. Thermogravimetric, size-exclusion chromatographic, and X-ray analyses of the copolymers suggest that the sequences of the copolymer chains consist of the segments containing the units originated from 7CC and those with TOX unit rich compositions.

  3. Rapid Communications

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    2. Highlight
    3. Articles
    4. Rapid Communications
    1. A novel templateless method to nanofibers of polyaniline derivatives with size control (pages 740–746)

      Jie Han, Yan Liu and Rong Guo

      Article first published online: 6 DEC 2007 | DOI: 10.1002/pola.22459

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      Poly(o-toluidine) (POT) nanofibers with controllable size (see figures) have been successfully synthesized through a chemical polymerization method in acidic aqueous solution using HAuCl4 as the oxidant instead of conventionally used ammonium persulfate without any external template for the first time. The gold nanoparticles generated during the polymerization processes are considered to act as catalysts to the oriented growth of POT nanofibers. The extension of this approach to nanofibers of other polyaniline derivatives, such as poly(o-methoxyaniline) is also successful, which suggests this is a general chemical route to nanofibers of polyaniline derivatives.

    2. Unconventional synthesis and characterization of novel abietic acid esters of hydroxypropylcellulose as potential macromolecular prodrugs (pages 747–752)

      Muhammad A. Hussain

      Article first published online: 6 DEC 2007 | DOI: 10.1002/pola.22461

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      It indicates the fabrication of novel macromolecular prodrug of abietic acid with hydroxypropylcellulose (HPC). Furthermore, it illustrates that this prodrug is an amphiphile. Both hydrophobic (abietic acid) and hydrophilic (HPC polymer backbone) cores of the amphiphile (macromolecular prodrug) are shown. Less substitution of abietic acid onto HPC polymer backbone is indicated in the illustration.

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