Journal of Polymer Science Part A: Polymer Chemistry

Cover image for Vol. 44 Issue 21

1 November 2006

Volume 44, Issue 21

Pages 6147–6503

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      Stereospecific living radical polymerization for simultaneous control of molecular weight and tacticity (pages 6147–6158)

      Masami Kamigaito and Kotaro Satoh

      Article first published online: 19 SEP 2006 | DOI: 10.1002/pola.21688

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      The simultaneous control of the molecular weights and the tacticity was attained by the judicious combinations of the living/controlled radical polymerizations based on the fast interconversion between the dormant and active species, and the stereospecific radical polymerizations mediated by the added Lewis acids or polar solvents via the coordination to the monomer/polymer terminal substituents. This was useful for various monomers including not only conjugated monomers, such as acrylamides and methacrylates, but also nonconjugated ones such as vinyl acetate and N-vinylpyrrolidone. Stereoblock polymers were easily obtained by the addition of the Lewis acids or by change of the solvents during the living radical polymerizations.

  2. Articles

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    1. Multi-center nature of ethylene polymerization catalysts based on 2,6-bis(imino)pyridyl complexes of iron and cobalt (pages 6159–6170)

      Yury V. Kissin, Changtao Qian, Guangyong Xie and Yaofeng Chen

      Article first published online: 20 SEP 2006 | DOI: 10.1002/pola.21689

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      2,6-Bis(imino)pyridyl complexes of Fe and Co in combination with MAO form very active homogeneouscatalytic systems for polymerization of ethylene. The Co complexes produce single-center catalysts whereas the Fe complexes produce catalysts with numerous types of active centers, as shown in the GPC resolution plot.

    2. Free radical polymerization with catalytic chain transfer: Using NMR to probe the strength of the cobalt–carbon bond in small molecule model reactions (pages 6171–6189)

      David A. Morrison, Thomas P. Davis, Johan P. A. Heuts, Barbara Messerle and Alexei A. Gridnev

      Article first published online: 20 SEP 2006 | DOI: 10.1002/pola.21662

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      This work examines the cobalt–carbon bond formation between a cobalt (II) macrocycle and a variety of radicals derived from vinyl compounds to facilitate a better understanding of the various factors affecting the cobalt–carbon bond strength in catalytic chain transfer polymerization. Several factors are shown to affect the reaction of the radical and the cobalt (II) species (and hence the strength of the cobalt–carbon bond in the resulting compound). A discussion on the relevance of this study to the behavior of different monomers in catalytic chain transfer reactions is included.

    3. Facile synthesis and high optical activity of poly(1-pentyne)s carrying amino-acid pendant groups (pages 6190–6201)

      Lo Ming Lai, Jacky W. Y. Lam and Ben Zhong Tang

      Article first published online: 20 SEP 2006 | DOI: 10.1002/pola.21713

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      Helical poly(1-pentyne)s containing different amino acid moieties and pendant terminal groups have been designed and synthesized. The polymers have been prepared in satisfactory yields with moderate yields by organorhodium catalysts. The polymers are thermally stable and show strong circular dichroism signals because of the helicity of the polyene backbone. The circular dichroism and ultraviolet absorptions of the polymers can be tuned with a solvent.

    4. Optimization of the nitroxide-mediated radical polymerization conditions for styrene and tert-butyl acrylate in an automated parallel synthesizer (pages 6202–6213)

      C. Remzi Becer, Renzo M. Paulus, Richard Hoogenboom and Ulrich S. Schubert

      Article first published online: 20 SEP 2006 | DOI: 10.1002/pola.21694

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      Controlled radical polymerization (CRP) techniques are providing tremendous advantages for the synthesis of well-defined polymers with desired architectures. Nitroxide-mediated radical polymerization is one of the three most important CRP techniques and is used in industrial applications. In this study, two important parameters of the nitroxide-mediated radical polymerization technique were examined. Several polymerization temperatures (from 90 to 130 °C) and free nitroxide concentrations (from 0 to 10%) were investigated for the nitroxide-mediated radical polymerization of styrene and tert-butyl acrylate with MAMA as SG-1 based initiator. The optimization of those parameters was performed in a parallel manner on an automated synthesis platform.

    5. A bicyclic conjugated diene monomer, tetrahydroindene, for cationic polymerization and a novel alicyclic hydrocarbon polymer with heat resistance (pages 6214–6225)

      Naomi Mizuno, Kotaro Satoh, Masami Kamigaito and Yoshio Okamoto

      Article first published online: 20 SEP 2006 | DOI: 10.1002/pola.21714

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      This study is directed toward the cationic polymerization of tetrahydroindene (THI; bicyclo[4.3.0]-2,9-nonadiene), a bicyclic conjugated diene monomer, with a series of Lewis acids. EtAlCl2 or SnCl4 afforded polymers with relatively high molecular weights (Mw > 50,000) and 1,4-enchainment bicyclic main-chain structures. The subsequent hydrogenation of the obtained poly(THI) resulted in a saturated alicyclic hydrocarbon polymer with a relatively high glass transition (Tg = 220 °C) and improved pyrolysis temperature (10% weight loss at 480 °C). The bicyclic diene was randomly copolymerized with cyclopentadiene with EtAlCl2 and subsequently hydrogenated into alicyclic copolymers with variable Tg values (70–220 °C).

    6. Michael addition polymerizations of difunctional amines (AA′) and triacrylamides (B3) (pages 6226–6242)

      Ding Wang, Zhiju Zheng, Chunyan Hong, Ye Liu and Caiyuan Pan

      Article first published online: 20 SEP 2006 | DOI: 10.1002/pola.21716

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      The Michael addition polymerizations of n-butylamine (BA; AA′) and 1,3,5-triacryloylhexahydro-1,3,5-triazine (TT; B3) displayed different behaviors than the polymerizations of diacrylates or diacrylamides (A2) with triamines (B2B′). Hyperbranched polymers were formed in the former case, regardless of whether the feed molar ratios of TT to BA were 1:1 or 1:2; and the surface functional groups (acryl or secondary amine) could be controlled by the variation of the feed molar ratios of BA to TT. The variation of the hyperbranched polymer properties could be easily achieved by the modification of their surface functional groups via Michael addition reactions.

    7. Copolymerization of carbon dioxide and cyclohexene oxide with zinc/β-ketoiminato complexes: Investigating the influence of the electron structure of zinc/β-ketoiminato complexes on the catalytic activity and resultant copolymer properties (pages 6243–6251)

      Binyuan Liu, Chunying Tian, Li Zhang, Weidong Yan and Wenjun Zhang

      Article first published online: 20 SEP 2006 | DOI: 10.1002/pola.21715

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      A series of zinc/β-ketoiminato complexes were synthesized. The activities toward the copolymerization of carbon dioxide with cyclohexene oxide were investigated. The catalytic activities of the zinc/β-ketoiminato complexes for the copolymerization, intrinsic viscosities, chemical compositions, and refined microstructures of the resultant copolymers could be tailored by the electron-donating or electron-withdrawing nature of the 3-position substituents on the β-ketoiminato ligand backbone of the zinc/β-ketoiminato complexes.

    8. Synthesis and characterization of new aromatic polyamides bearing crown ethers and acyclic ethylene oxide units in the pendant structure. III. Benzo-18-crown-6 systems and their open-chain counterparts (pages 6252–6269)

      Verónica Calderón, Gert Schwarz, Félix García, María J. Tapia, Artur J. M. Valente, Hugh D. Burrows and José Miguel García

      Article first published online: 20 SEP 2006 | DOI: 10.1002/pola.21710

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      The synthesis and standard properties of polyisophthalamides with pendant benzo-X-crown-Y (X,Y = 12,4, 15,5, or 18,6) and their dipodal counterparts are described and correlated with the chemical structure (the thermal and mechanical properties, water uptake, and solubility). Polymerization under standard conditions yields insoluble gels, and a procedure to disregard gel formation is described. Furthermore, a plausible explanation accounting for such behavior is discussed in terms of cyclic oligoamide formation (Kricheldorf's kinetically controlled step growth polymerization) and subsequent threading with a growing polyamide chain to yield rotaxanes, catenanes, and polycatenanes. Moreover, to get insight into the polymer microstructures, films obtained by casting have been studied with wide-angle X-ray scattering, scanning electron microscopy, and hydrochloric acid transport studies through dense membranes.

    9. Lightly crosslinked, mesomorphic networks obtained through the reaction of dimeric, liquid-crystalline epoxy–imine monomers and heptanedioic acid (pages 6270–6286)

      David Ribera, Marta Giamberini, Angels Serra and Ana Mantecón

      Article first published online: 27 SEP 2006 | DOI: 10.1002/pola.21681

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      Various dimeric, liquid-crystalline epoxy–imine monomers, differing in the length of the central aliphatic spacer or the dipolar moments, were reacted with heptanedioic acid. In some cases, liquid-crystalline systems were obtained, depending on both the polarization of the mesogen and the reaction temperature. Dynamic mechanical thermal analysis suggested that the presence of the mesogen directly incorporated into the main chain increased the lifetimes of the elastic modes both in the isotropic phase and in the liquid-crystalline phase.

    10. Novel doubly polymerizable functional norbornene: Its synthesis, reactivity, and macromolecular architectures from a dual cure via ring-opening metathesis polymerization and radical photopolymerization (pages 6287–6298)

      Der-Jang Liaw, Ching-Cheng Huang and Shou-Mau Hong

      Article first published online: 28 SEP 2006 | DOI: 10.1002/pola.21684

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      A novel doubly polymerizable functional norbornene, 5-(methacryloyloxyethylamino carboxylmethyl)bicyclo[2.2.1]hept-2-ene(NBMOACM), was prepared. The ring-opening metathesis polymerization of NBMOACM was carried out to prepare polymers with crosslinkable side chains with the Grubbs catalyst. Increasing the ratio of the monomer concentration to the catalyst concentration resulted in the formation of higher molecular weight polymers. Poly(NBMOACM) was incorporated into poly(methyl methacrylate) to produce AB crosslinked materials.

    11. Kinetics and electron spin resonance study of the radical polymerization of n-butyl acrylate mediated by a nitroxide precursor: C-phenyl-N-tert-butylnitrone (pages 6299–6311)

      Valérie Sciannamea, Maxime Bernard, Jean-Marie Catala, Robert Jérôme and Christophe Detrembleur

      Article first published online: 27 SEP 2006 | DOI: 10.1002/pola.21698

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      This article reports for the first time the controlled radical homopolymerization of n-butyl acrylate mediated by a specific nitrone, C-phenyl-N-tert-butylnitrone, as a precursor of nitroxide and a parent alkoxyamine by a reaction with azobisisobutyronitrile. The choice of the nitrone is critical, N-tert-butyl-α-isopropylnitrone, for instance, being ineffective. A two-step process has been established, which consists of the prereaction of the nitrone and the initiator in toluene at 85 °C to preform nitroxide and alkoxyamine, followed by monomer polymerization at a higher temperature (110 °C). The in situ formation of nitroxides during the prereaction and polymerization has been monitored by electron spin resonance. These data, completed by the polymerization kinetics, have been used to approach the mechanism of this in situ nitroxide-mediated polymerization. All the key parameters that govern the process have been determined. The polymerization resumption of n-butyl acrylate and block copolymerization with styrene initiated by a poly(n-butyl acrylate) macroinitiator have also been performed with success, and this emphasizes the livingness of the poly(n-butyl acrylate) chains.

    12. Polyrotaxane derivatives. I. Preparation of modified polyrotaxanes with nonionic functional groups and their solubility in organic solvents (pages 6312–6323)

      Jun Araki and Kohzo Ito

      Article first published online: 27 SEP 2006 | DOI: 10.1002/pola.21717

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      Various polyrotaxane modification reactions, such as methylation, hydroxypropylation, tritylation, acetylation, trimethylsilylation, phenylcarbamation, dansylation, and nitration, were examined to obtain polyrotaxane derivatives, in which various functional groups were attached to cyclodextrin moieties. Although the nitrate could not be obtained because of significant degradation of the polyrotaxane under the conditions examined, other derivatives were successfully prepared under moderate conditions. The introduction of these functional groups, which was assessed with Fourier transform infrared and NMR spectroscopy, changed the solubility of the polyrotaxane drastically; that is, the polyrotaxane derivatives thus obtained were soluble in various organic solvents other than the conventional solvents (dimethyl sulfoxide and aqueous NaOH) used for the unmodified polyrotaxane.

    13. Polymer having a trithiocarbonate moiety in the main chain: Application to reversible addition–fragmentation chain transfer controlled thermal and photoinduced monomer insertion polymerizations (pages 6324–6331)

      Suguru Motokucho, Atsushi Sudo and Takeshi Endo

      Article first published online: 27 SEP 2006 | DOI: 10.1002/pola.21718

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      A polymer having a trithiocarbonate moiety in its main chain was synthesized with a cyclic, five-membered dithiocarbonate as a building block. The trithiocarbonate in the polymer acted as a reversible addition–fragmentation chain transfer reagent to mediate a controlled insertion polymerization of styrene into the polymer main chain. The insertion polymerization of styrene was successfully induced not only thermally but also by ultraviolet irradiation.

    14. Synthesis of novel boron-containing epoxy–novolac resins and properties of cured products (pages 6332–6344)

      C. Martín, G. Lligadas, J. C. Ronda, M. Galià and V. Cádiz

      Article first published online: 27 SEP 2006 | DOI: 10.1002/pola.21726

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      Epoxy–novolac resins were synthesized and modified with different contents of bis(benzo-1,3,2-dioxa-borolanyl)oxide or bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolanyl)oxide. The boron-modified resins were autocatalytically crosslinked or crosslinked with BF3MEA and their thermal stability and flame retardancy were determined by thermogravimetric analysis and LOI values. These LOI values for the bis(benzo-1,3,2-dioxa-borolanyl)oxide derivatives were higher than the boron-free novolac resins, which shows the benefit of the presence of boron. To test the role of boron in the enhancement of flammability, scanning electronic microscopy and energy-dispersive X-ray spectroscopy images were made.

    15. New heterobicationic hemicyanine dyes: Synthesis, spectroscopic properties, and photoinitiating ability (pages 6345–6359)

      Janina Kabatc, Beata Jędrzejewska and Jerzy Pączkowski

      Article first published online: 27 SEP 2006 | DOI: 10.1002/pola.21729

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      New heterobicationic hemicyanine dyes coupled with n-butyltriphenylborate anions have been tested as visible-light photoinitiators of acrylic monomer polymerization. They show significantly enhanced photoinitiation ability in comparison with their monocationic analogues. This is attributed to an artificially increased concentration of the n-butyltriphenylborate anion (acting as an electron donor) in proximity to the electron-accepting excited cyanine dye chromophore.

    16. Novel polymers with a high carboxylic acid loading (pages 6360–6377)

      Anders D. Thomsen, Eva Malmström and Søren Hvilsted

      Article first published online: 27 SEP 2006 | DOI: 10.1002/pola.21730

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      Poly(4-hydroxystyrene)-based (co)polymers have been used as scaffolds in a click-chemistry approach to design carboxylic acid polymers. Poly(4-hydroxystyrene)s have been alkyne-functionalized through Williamson ether syntheses and subsequently applied in click reactions with four different mono- or difunctional carboxylic acid azides. Differential scanning calorimetry investigations show a clear correlation between the functional group modifications on the polymer and the glass-transition temperatures.

    17. Amphiphilic conetworks. II. Novel two-step synthesis of poly[2-(dimethylamino)ethyl methacrylate]–polyisobutylene, poly(N-isopropylacrylamide)–polyisobutylene, and poly(N,N-dimethylacrylamide)–polyisobutylene hydrogels (pages 6378–6384)

      Luděk Toman, Miroslav Janata, Jiří Spěváček, Jiří Brus, Antonín Sikora, Petra Látalová, Petr Holler, Petr Vlček and Barbora Dvořánková

      Article first published online: 27 SEP 2006 | DOI: 10.1002/pola.21736

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      Amphiphilic conetworks consisting of poly[2-(dimethylamino) ethyl methacrylate], poly(N-isopropylacrylamide), or poly (N,N-dimethylacrylamide) and polyisobutylene chains were prepared by the cationic copolymerization of isobutylene with 3-isopropenyl-α,α-dimethylbenzyl isocyanate. The isocyanate groups of the isobutylene/3-isopropenyl-α,α-dimethylbenzyl isocyanate random copolymer were transformed in situ into methacrylate groups by a reaction with 2-hydroxyethyl methacrylate. The resulting methacrylate-multifunctional polyisobutylene was then copolymerized radically with 2-(dimethylamino)ethyl methacrylate, N-isopropylacrylamide, or N,N-dimethylacrylamide, giving rise to transparent amphiphilic conetworks.

    18. Synthesis and properties of poly(amic acid)s and polyimides based on 2,2′,6,6′-biphenyltetracarboxylic dianhydride (pages 6385–6393)

      Katsuya Sakayori, Yuji Shibasaki and Mitsuru Ueda

      Article first published online: 28 SEP 2006 | DOI: 10.1002/pola.21737

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      Poly(amic acid)s (PAAs) having the high solution stability and transmittance at 365 nm for photosensitive polyimides (PSPIs) have been developed. PAAs with a twisted conformation in the main chains were prepared from 2,2′,6,6′-biphenyltetracarboxylic dianhydride (2,2′,6,6′-BPDA) and aromatic diamines. Imidization of PAAs was achieved by chemical treatment using trifluoroacetic anhydride. Among them, the PAA derived from 2,2′,6,6′-BPDA and 4,4′-(1,3-phenylenedioxy)dianiline was converted to the polyimide by thermal treatment.

    19. A novel synthesis of polymer brush on multiwall carbon nanotubes bearing terminal monomeric unit (pages 6394–6401)

      Jin Uk Ha, Myunghun Kim, Jeongwoo Lee, Soonja Choe, In Woo Cheong and Sang Eun Shim

      Article first published online: 27 SEP 2006 | DOI: 10.1002/pola.21738

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      Reactive terminal groups are attached on the surface of carboxylated CNTs by reaction with hexamethylene diisocyanate and the following reaction with methacrylamide. Herein, the CNTs having the reactive vinyl groups are named “CNT-mer”. The synthesized CNT-mer is used to graft PS chains via a simple in situ polymerization.

    20. Characteristic properties of film prepared from poly(L-lactide)-grafted dextran of a relatively high sugar unit content as a degradable biomaterial (pages 6402–6409)

      Tatsuro Ouchi, Tomohiro Kontani, Rie Aoki, Toshifumi Saito and Yuichi Ohya

      Article first published online: 27 SEP 2006 | DOI: 10.1002/pola.21750

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      The bulk phase for poly(L-lactide)-grafted dextran films with a sugar unit content of 16–25 wt % was found by transmission electron microscopy to form a lamellar type of nanophase-separated structure composed of approximately 80–100-nm-wide nanodomains because of their amphiphilic and branched structures. The hydrophobic top surface for a Dex-g-PLLA film with a sugar unit content of 25 wt % covered with PLLA segments was confirmed by atomic force microscopy phase images to be easily converted to a wettable top surface covered with hydrophilic dextran aggregates showing an 8–10-nm-wide honeycomb pattern by means of annealing in water.

    21. Nitroxide-mediated controlled statistical copolymerizations of N-isopropylacrylamide with N-tert-butylacrylamide (pages 6410–6418)

      Orla Gibbons, William M. Carroll, Fawaz Aldabbagh and Bunichiro Yamada

      Article first published online: 27 SEP 2006 | DOI: 10.1002/pola.21751

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      The conventional polymerization and nitroxide-mediated polymerization (NMP) {for which the nitroxide is N-tert-butyl-N-[1-diethylphosphono-(2,2-dimethylpropyl)]nitroxide} of N-isopropylacrylamide and N-tert-butylacrylamide are described. The reactivity ratios are the same at different temperatures and in different solvents with the conventional and NMP systems. Control in NMP has been observed with 2,2′-azobisisobutyronitrile/N-tert-butyl-N-[1-diethylphosphono-(2,2-dimethylpropyl)]nitroxide and a polystyrene macroinitiator, with the living character of poly(N-isopropylacrylamide-stat-N-tert-butylacrylamide) confirmed by chain extension with styrene.

    22. Triblock copolymer synthesis via controlled radical polymerization in solution using S-tert-alkyl-N,N-alkoxycarbonylalkyldithiocarbamate RAFT agents (pages 6419–6434)

      Raf Bussels, Christianne Bergman-Göttgens, Bert Klumperman, Jan Meuldijk and Cor Koning

      Article first published online: 27 SEP 2006 | DOI: 10.1002/pola.21746

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      This paper presents the solution homopolymerization, and random and block copolymerization of acrylic monomers, mediated using a difunctional dithiocarbamate RAFT agent. Fairly good control was obtained over the solution polymerization of various acrylic monomers, including the solution copolymerization of n-butyl acrylate with methacrylic acid, mediated with this RAFT agent. Finally, triblock copolymer synthesis, starting from the macromolecular intermediates produced in the homo- and copolymerization experiments, was studied, and was shown to be successful. The observed relatively broad molar mass distributions could be explained by a partial decomposition of the dithiocarbamate-based RAFT agent during synthesis and/or polymerization.

    23. Design and synthesis of multifunctional glycidyl ethers that undergo frontal polymerization (pages 6435–6448)

      James V. Crivello

      Article first published online: 27 SEP 2006 | DOI: 10.1002/pola.21761

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      A series of multifunctional glycidyl ether monomers have been designed and synthesized that display well-behaved photoactivated cationic frontal polymerization characteristics. In all cases, the monomers have been predicted to form secondary oxonium ions (I) stabilized by multidentate proton coordination. The localized application of heat to such systems results in the rapid, highly exothermic ring-opening frontal polymerization of the monomer. Optical pyrometry is a convenient analytical method that has been employed to study various aspects of the frontal polymerizations of these monomers.

    24. Synthesis, characterization, and electrical properties of polypyrrole/multiwalled carbon nanotube composites (pages 6449–6457)

      Tzong-Ming Wu and Shih-Hsiang Lin

      Article first published online: 27 SEP 2006 | DOI: 10.1002/pola.21724

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      This figure schematically shows the formation mechanism of polypyrrole (PPy)/multiwalled carbon nanotube composites (MWCNT) composites synthesized by in situ chemical oxidation polymerization directed by various concentrations of cationic surfactant cetyltrimethylammonium bromide (CTAB). The presence of the π–π* electron interaction between CTAB/MWCNT template and the pyrrole monomer serves as the core and self-assembly hard template during the formation of the tubular nanostructure with the thickness of the PPy layer in the range of 20–40 nanometers, depending on the concentration of CTAB. Electrical conductivities of PPy/MWCNT composites are 1–2 orders of magnitude higher than those of PPy without MWCNTs.

    25. A3-type star polymers via click chemistry (pages 6458–6465)

      O. Altintas, B. Yankul, G. Hizal and U. Tunca

      Article first published online: 27 SEP 2006 | DOI: 10.1002/pola.21728

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      We report a simple preparation of three-armed (A3-type) star polymers based on the arm-first technique, using a click-reaction strategy between a well-defined azide-end-functionalized polystyrene, poly(tert-butyl acrylate), or poly(ethylene glycol) precursor and a trisalkyne-functional initiator, 1,1,1-tris[4-(2-propynyloxy)phenyl]ethane. The click-reaction efficiency for A3-type star formation has been investigated with gel permeation chromatography measurements (refractive-index detector). The gel permeation chromatography curves have been split with the deconvolution method (Gaussian area), and the efficiency of A3-type star formation has been found to be 87%.

    26. Synthesis and properties of noncoplanar rigid-rod aromatic polyhydrazides and poly(1,3,4-oxadiazole)s containing phenyl or naphthyl substituents (pages 6466–6483)

      Guey-Sheng Liou, Sheng-Huei Hsiao and Yi-Kai Fang

      Article first published online: 27 SEP 2006 | DOI: 10.1002/pola.21747

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      Two series of organosoluble rigid-rod aromatic polyhydrazides and poly(1,3,4-oxadiazole)s have been synthesized from 2,2′-phenyl or naphthyl –substituted biphenyl-units aromatic diacid monomer, 2,2′-diphenylbiphenyl-4,4′-dicarboxylic acid 4 and 2,2′-dinaphthylbiphenyl-4,4′-dicarboxylic acid 5 which were a blue light (425 and 438 nm) emitter with fluorescence quantum efficiency 4.6 and 17.7%, respectively. These Polyhydrazides and poly(1,3,4-oxadiazole)s high-performance polymers have strong fluorescence emissions in the blue region with quantum yields from 2.8 to 37.9%, and two stability reversible reduction redox potential Eonset −1.42 to −1.79 V vs.Ag/AgCl in N,N-dimethylformamide solution. [Color version of the adjacent figure can be viewed in the online issue, which is available at www.interscience.wiley.com]

  3. Rapid Communication

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    1. Cationic polymerization of 2-hydroxymethyltetrahydrofuran (pages 6484–6493)

      Melania Bednarek and Przemysław Kubisa

      Article first published online: 27 SEP 2006 | DOI: 10.1002/pola.21709

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      The cationic polymerization of 2-hydroxymethyltetrahydrofuran proceeds with the elimination of water. This has been clearly observed with matrix-assisted laser desorption/ionization time-of-flight spectroscopy. In the spectra, a series of signals appears for each oligomer with molecular weights corresponding to the following: molecular weight = n ×102.16 (the molecular weight of the monomeric unit) − m × 18 (with m between 0 and n − 1). A possible reason of this behavior is discussed.

  4. Notes

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      Innovation in material science: The chameleon block copolymer (pages 6494–6497)

      Judit E. Puskas, Lucas Dos Santos and Gabor Kaszas

      Article first published online: 27 SEP 2006 | DOI: 10.1002/pola.21693

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      This note to the editor is the first journal publication of the chameleon thermoplastic elastomer with entropy-driven phase separation. We have discovered that block copolymers with a high-molecular-weight, dendritic (arborescent) polyisobutylene core and poly(para-methylstyrene) end blocks can manifest themselves either as rubber or as plastic, depending on their environment. The behavior is thermally irreversible. This material represents a new concept in material science: the entropy-driven thermoplastic elastomer.

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      Effect of desilylation on the optical and electroluminescence properties of poly[2-(3-dimethyldodecylsilylphenyl)-1,4-phenylenevinylene] (pages 6498–6503)

      B. Vijaya Kumar Naidu, Sung-Ho Jin, Sung-Chul Kim, Won-Suk Shin, Jae Wook Lee and Yeong-Soon Gal

      Article first published online: 27 SEP 2006 | DOI: 10.1002/pola.21734

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      A new poly(2-phenyl-1,4-phenylenevinylene) polymer was prepared through a desilylation reaction with poly[2-(3-dimethyldodecylsilylphenyl)-1,4-phenylenevinylene], which was synthesized by Gilch polymerization. Polymer light-emitting diodes (PLEDs) with an indium tin oxide/poly(3,4-ethylenedioxythiophene)-doped poly(styrene sulfonate)/emittinglayer/cathode configuration were fabricated with LiF/Al and tris(8-quinolinolate)aluminum/LiF/Al cathode compositions, and the PLED performances of the pristine and desilylated polymers were compared. A PLED fabricated with the poly[2-(3-dimethyldodecylsilylphenyl)-1,4-phenylenevinylene] polymer with a LiF/Al bilayer cathode showed the highest luminescence of 1904 cd/m2 with a luminescence efficiency of 1.3 cd/A.

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