Journal of Polymer Science Part A: Polymer Chemistry

Cover image for Vol. 41 Issue 23

1 December 2003

Volume 41, Issue 23

Pages 3713–3862

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      Dendrimers and other dendritic macromolecules: From building blocks to functional assemblies in nanoscience and nanotechnology (pages 3713–3725)

      Jean M. J. Fréchet

      Version of Record online: 13 OCT 2003 | DOI: 10.1002/pola.10952

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      The architectural and functional characteristics of dendrimers and dendritic polymers make them attractive in the development of functional nanosystems in areas as varied as drug delivery, catalysis, and nanolithography.

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    1. Synthesis and characterization of hyperbranched aromatic poly(ether imide)s with terminal amino groups (pages 3726–3735)

      Yao-Te Chang, Ching-Fong Shu, Chyi-Ming Leu and Kung-Hwa Wei

      Version of Record online: 14 OCT 2003 | DOI: 10.1002/pola.10939

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      The direct self-polycondensation of a new AB2-type monomer, 4-{4-[di(4-aminophenyl)methyl]phenoxy}phthalic acid, in the presence of triphenylphosphite as an activator afforded a hyperbranched poly(ether imide) with chain-ending amino groups. The degree of branching was estimated to be 56% on the basis of 1H NMR spectroscopy analysis. The amino groups at the chain ends were readily accessible to reagents in solution and were converted into a variety of functional groups. Transmission electron microscopy analysis revealed that the hyperbranched polymer grafted with polyhedral oligomeric silsesquioxane aggregates to form a nanocomposite material.

    2. Synthesis and characterization of novel hyperbranched poly(imide silsesquioxane) membranes (pages 3736–3743)

      Chunqing Liu, Nathaniel Naismith, Yongqing Huang and James Economy

      Version of Record online: 17 OCT 2003 | DOI: 10.1002/pola.10941

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      A new family of hyperbranched polymers with chemical bonds between the hyperbranched polyimide (HPI) and polysilsesquioxane network was synthesized by the reaction of an amine-terminated aromatic HPI with 3-glycidoxypropyl trimethoxysilane (GPTMS), followed by hydrolysis and polycondensation in the presence of an acid catalyst. The hyperbranched poly(imide silsesquioxane) (HPIS) membranes were fabricated by the casting of the aforementioned polymer solution onto a NaCl optical flat, which was followed by heating at 80 °C for 24 h. The membranes were characterized by Fourier transform infrared, X-ray diffraction, thermogravimetric analysis, scanning electron microscopy, N2 adsorption and desorption, and CO2 adsorption and desorption.

    3. Modification of the microstructure of emulsion polymers (pages 3744–3749)

      Pedro Ilundain, Daniel Alvarez, Louis Da Cunha, Rafael Salazar, María J. Barandiaran and José M. Asua

      Version of Record online: 14 OCT 2003 | DOI: 10.1002/pola.10950

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      The effect of treating several commercially important emulsion polymers with different initiator systems was investigated. The initiator system producing highly reactive tert-butoxyl radicals was able to cause polymer modification. This represented an opportunity to extend the range of properties achievable with a given emulsion polymer.

    4. Biodegradable/biocompatible ABC triblock copolymer bearing hydroxyl groups in the middle block (pages 3750–3760)

      Mariusz Gadzinowski and Stanislaw Sosnowski

      Version of Record online: 14 OCT 2003 | DOI: 10.1002/pola.10955

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      New biodegradable/biocompatible ABC block copolymers, poly(ethylene oxide)-b-poly(glycidol)-b-poly(L,L-lactide) (PEO-PGly-PLLA), were synthesized. The copolymers were susceptible for further modifications with hydroxyl side groups of the middle PGly block. PEO-PGly-PLLA copolymers dissolved in water formed nanoparticles with diameters of 25 nm with a hydrophobic PLLA core and hydrophilic PEO shell.

    5. Synthesis and characterization of poly[phenyl(fluoroalkyloxaalkane)silanediyl]s (pages 3761–3767)

      Vjacheslav V. Zuev and Nikolai K. Skvortsov

      Version of Record online: 21 OCT 2003 | DOI: 10.1002/pola.10945

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      Monomeric fluoroalkoxyalkyl(phenyl)dichlorosilanes were synthesized with quantitative yields by hydrosilylation of allyl ethers of fluoroalcohols with phenyldichlorosilane with Pt(PH3Sb)2Cl2: complex as a catalyst. Starting from these monomers, corresponding polysilanes with weight-average molecular weights of 2–3 × 104 were obtained by the Wurtz reaction. Increasing the CF2 groups containing two to six monomer units caused the char yields to increase from 3 to 48% at 800 °C in air. The emission characteristics of these polysilanes in a chloroform solution were examined. They had a narrow peak at 344 nm with a small Stokes shift (∼20 nm).

    6. Ethylene polymerization over transition-metal supported catalysts. II. Cr on zeolite, silica, and charcoal: Characterization and activity studies (pages 3768–3780)

      Y. Zhang, I. Matos, M. A. N. D. A. Lemos, Filipe Freire, Teresa G. Nunes, A. M. Botelho do Rego, R. T. Henriques, I. F. Fonseca, M. M. Marques and F. Lemos

      Version of Record online: 21 OCT 2003 | DOI: 10.1002/pola.10947

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      Cr catalysts prepared with three different supports—zeolites, silica, and charcoal—were characterized by cyclic voltammetry, electron spin resonance, X-ray photoelectron spectroscopy, and silicon-29 magic-angle spinning nuclear magnetic resonance and investigated in the reaction of ethylene polymerization.

    7. Biodegradable polycaprolactone–polyanhydrides blends (pages 3781–3787)

      Shimon Ben-Shabat, Elias Abuganima, Aliza Raziel and Abraham J. Domb

      Version of Record online: 14 OCT 2003 | DOI: 10.1002/pola.10958

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      Biodegradable polymers based on a blend of polycaprolactone (PCL) and aliphatic polyanhydrides with various monomers lengths were prepared to obtain the desired polymer blends. The results demonstrate that the heat of fusion (dH) of the polyanhydride or of the blend is increased in relation to the length of the aliphatic chain. However, the blends have different properties than pure polyanhydride. Drug release studies from blends of polycaprolactone (PCL) and aliphatic polyanhydrides demonstrated first-order kinetics of the release rate. Based on theoretical calculation of the interaction factor a blend of polycaprolactone (PCL) and poly(dodecanedeoic anhydride) (PDD) was chosen for further elucidation of its thermal, mechanical, and degradation properties.

    8. Crosslinked poly(ester anhydride)s based on poly(ε-caprolactone) and polylactide oligomers (pages 3788–3797)

      Antti O. Helminen, Harri Korhonen and Jukka V. Seppälä

      Version of Record online: 15 OCT 2003 | DOI: 10.1002/pola.10951

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      Crosslinked poly(ester anhydride)s were prepared from ε-caprolactone-, L-lactide-, and D,L-lactide-based oligomers. After functionalizations with succinic and methacrylic anhydride, the oligomers possessed crosslinkable methacrylate groups and labile anhydride bonds. Cured polymer networks degraded in hydrolysis tests in a matter of days through a two-step degradation profile, in which the rapid cleavage of anhydride bonds was followed by the dissolution or degradation of the polyester blocks. Characteristics of surface erosion were observed in the degradation of a network prepared from small PCL oligomers. The network contained labile anhydride bonds almost to full mass loss.

    9. Anionic iron(II) alkoxides as initiators for the controlled ring-opening polymerization of lactide (pages 3798–3803)

      David S. McGuinness, Edward L. Marshall, Vernon C. Gibson and Jonathan W. Steed

      Version of Record online: 17 OCT 2003 | DOI: 10.1002/pola.10946

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      Hetero-bimetallic Fe(II) alkoxide/aryloxides were evaluated as initiators for the ring-opening polymerization of rac-lactide. {[Tetrahydrofuran (THF)]NaFe(OtBu)3}2 (1) and [(THF)4Na2Fe(2,6-diisopropylphenolate)4] (2) both polymerized lactide efficiently at room temperature, with complex 1 affording better control over the molecular weight parameters of the resultant polymer.

    10. Dispersion polymerization of styrene in carbon dioxide stabilized by copolymers of poly(propylene glycol) methacrylate and 2-(perfluorooctyl)ethyl methacrylate (pages 3804–3815)

      Lunhan Ding and Susan V. Olesik

      Version of Record online: 23 OCT 2003 | DOI: 10.1002/pola.10953

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      The dispersion polymerization of styrene in CO2 using a series of copolymers of poly(propylene glycol) methacrylate (PPGMA) and 2-(perfluorooctyl)ethyl methacrylate (FOEMA) as the polymerization dispersants is described. It is demonstrated that copolymers/polymer of PPGMA and FOEMA containing 52–100% FOEMA can be used as effective dispersants for the polymerization, and the composition of copolymeric dispersant has a dramatic effect on both the polymerization yield and the morphology of the resulting polystyrene. The effects of the concentration of copolymeric dispersants, the concentration of the monomer, and the reaction pressure also were investigated.

    11. Photocationic and radical polymerizations of epoxides and acrylates by novel sulfonium salts (pages 3816–3827)

      Eiji Takahashi, Fumio Sanda and Takeshi Endo

      Version of Record online: 23 OCT 2003 | DOI: 10.1002/pola.10914

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      Novel sulfonium salts [methyl-, 2-indany-, or 1-ethoxycarbonylethyl methyl-2-naphthylsulfonium hexafluorophosphate and 2-indany-, 1-ethoxycarbonylethyl-, 2-methyl-2-phenylpropyl-, 2-phenylpropyl-, 2-phenylethyl-, 2-(4-methoxyphenyl)-ethyl-, or 3-(4-methoxyphenyl)-2-propyl methylphenylsulfonium hexafluorophosphates] were synthesized by the reaction of dimethylsulfate and the corresponding sulfides followed by anion exchange with KPF6. These sulfonium salts could polymerize epoxy monomers at lower temperatures than previously reported for benzylsulfonium salt initiators. In particular, sulfonium salts with naphthyl groups showed higher photoactivity than already reported for di(4-tert-butylphenyl)iodonium and triphenylsulfonium hexafluorophosphates. These sulfonium salts showed higher activity in photoradical polymerization and photocationic polymerization. The photopolymerization was accelerated by the addition of 4-methoxy-1-naphthol, N-ethylcarbazole, 2,4-dimethylthioxanthone, phenothiazine, and 2-ethyl-9,10-dimethoxyanthracene as photosensitizers.

    12. Novel N-methylbenzothiazolium salts as hardeners for epoxy and acrylate monomers (pages 3828–3837)

      Eiji Takahashi, Fumio Sanda, Takakazu Yamamoto and Takeshi Endo

      Version of Record online: 23 OCT 2003 | DOI: 10.1002/pola.10922

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      Novel N-methylbenzothiazolium salts [N-methyl-2-benzylthiobenzothiazolium, N-methyl-2-(4-nitrobenzylthio)benzothiazolium, N-methyl-2-(1-ethoxycarbonylethylthio)benzothiazolium, and N-methyl-2-methylthiobenzothiazolium hexafluoroantimonates] were synthesized by the reaction of the corresponding 2-substituted benzothiazole with dimethylsulfate, followed by anion exchange with KSbF6. These benzothiazolium salts cationically polymerized an epoxy monomer by photoirradiation. They also polymerized an acrylate monomer via a photoradical process. The use of aromatic compounds such as 2-ethyl-9,10-dimethoxyanthracene as photosensitizers was effective in enhancing the polymerization. These benzothiazolium salts also served as thermal cationic initiators.

    13. Macrocycles. XXVIII. Cyclic poly(benzonitrile ether)s derived from bisphenol A (pages 3838–3846)

      Hans R. Kricheldorf, Mazen Garaleh and Gert Schwarz

      Version of Record online: 23 OCT 2003 | DOI: 10.1002/pola.10928

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      Free bisphenol A and its bistrimethylsilyl derivative were polycondensed with 2,4-difluorobenzonitrile, 2,6-difluorobenzonitrile, or 3,5-difluorobenzonitrile, and the reaction conditions were optimized for the formation of cyclic polyethers.

    14. Hyperbranched polymers as scaffolds for multifunctional reversible addition–fragmentation chain-transfer agents: A route to polystyrene-core-polyesters and polystyrene-block-poly(butyl acrylate)-core-polyesters (pages 3847–3861)

      Martin Jesberger, Leonie Barner, Martina H. Stenzel, Eva Malmström, Thomas P. Davis and Christopher Barner-Kowollik

      Version of Record online: 23 OCT 2003 | DOI: 10.1002/pola.10976

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      The polyester core-based RAFT agents were successfully employed to synthesize star polymers of n-butyl acrylate and styrene of low polydispersity (PDI < 1.3) in a living free-radical process. While the polyester core based RAFT agent mediated polymerization of n-butyl acrylate display a linear evolution of the number average molecular weight, the corresponding styrene based-system reached a maximum molecular weight at intermediate conversions. The resulting star polymers were subsequently used as platforms for the preparation of star block copolymers of styrene and n-butyl acrylate with a polyester core with low polydispersities.

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