Polymers - Vol. 58, No. 5 (May, 2009)

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Vol. 58, No. 5 May, 2009)

Design of a Novel Cell Surface-Retained Polymer for Cell Surface Engineering
Kenichi NIIKURA and Kuniharu IJIRO
Research Institute of Electronic Science, Hokkaido University

We have developed a new cell surface modification method using a synthetic cationic polymer (Niikura et al. ChemBioChem 2009, 10, 230). Generally, cationic polymers are taken up into cells for time periods of a few minutes, and thus have been used as therapeutic carrier materials. We report now that the secondary amines-based cationic polymer significantly elongates the retention time on the cell membrane without cytotoxicity. These polymers can act as an effective scaffold for the display of artificial ligands, providing a basic methodology by which cellular adhesion can be controlled efficiently, including specific cell attachment and cell-cell contact. Polymer Preprints, Japan 2008, 57, 5080..

Synthesis of LactateÐ (LAÐ) Incorporated Polymer using a LAÐPolymerizing Enzyme
Kenji TAJIMA*, Yasuharu SATOH, Toshifumi SATOH, Seiichi TAGUCHI, Toyoji KAKUCHI, and Masanobu MUNEKATA
Division of Biotechnology and Macromolecular Chemistry Graduate School of Engineering, Hokkaido University
We have developed a water-organic solvent twoÐphase reaction system (TPRS) for in vitro polyhydroxyalkanoates (PHA) synthesis, in which hydroxyalkanoylCoA was continuously supplied to a PHA synthase by the ester exchange reaction (Tajima et al. Macromolecules, 2004, 37, 4544). Since the TPRS can supply substrates with various structures to PHA synthase, it is possible to find a combination of a substrate and enzyme that can recognize and polymerize the substrate. By applying the TPRS in a screening process, we found a suitable lactateÐ (LAÐ) polymerizing enzyme from a pool of PHA synthases. The enzyme was an engineered PHA synthase (Taguchi et al. Macromol. Biosci. 2004, 4, 146), which stereoselectively copolymerized (R)Ðlactate together with (R)Ð3Ð hydroxybutyrate. The molar ratios of LA in the copolymers were controllable in the range of 0 to 36 mol%. Polymer Preprints, Japan 2009, 58, 2101.

Thermal Nanoimprint Lithography with Photo-Reactive Monolayer
Masaru NAKAGAWA
Institute of Multidisciplinary Research of Advanced Materials, Tohoku University
The photo-reactive monolayer was formed by the adsorbate molecule bearing a mercapto group and a benzophenone moiety on an Au-deposited substrate. Ultraviolet-light (UV) exposure caused the benzophenone moiety to induce the photochemical graft reaction with a thermoplastic hydrocarbon polymer. The photo-induced graft reaction suppressed the dewetting of a polymer thin film on the substrate. The dewetting suppression was achieved at an exposure dose of 2 J cm-2 at the irradiation wavelength of 254 nm. The dewetting suppression enabled us to fabricate reliable fine patterns of the polymer film by thermal nanoimprint lithography and the Au film by subsequent wet etching. Polymer Preprints, Japan 2009, 58, 1305.

Perfluoro-1,3-Propanedisulfonic Acid/Silica Nanocomposites Possessing No Weight Loss Characteristic Even at 800 ûC Under Atmospheric Conditions.
Xinlai LIU1, Tsukasa TASHIMA1, Kota OMORI2, Tsunetoshi HONDA2, Hiroyuki YATSUYANAGI2, and Hideo SAWADA1*
1Graduate School of Science and Technology, Hirosaki University 2JEMCO Inc.
Perfluoro-1,3-propanedisulfonic acid/silica nanocomposites were prepared by the reactions of tetraethoxysilane and the corresponding disulfonic acid in the presence of silica nanoparticles under alkaline conditions. We observed no weight loss of the fluorinated disulfonic acid/silica nanocomposites, in which the theoretical contents of disulfonic acid are 15 ~ 47 %, at 800 ûC as well as that of the original silica nanoparticles. Interestingly, these calcinated fluorinated silica nanocomposites were found to emit fluorescence with a peak maximum around 313 nm in methanol solutions, although we failed to observe such fluorescence behaviors for the corresponding fluorinated disulfonic acid/silica nanocomposites before the calcination process. Polymer Preprints, Japan 2009, 58, 1321.

Strong Magnetic Interaction Induced by the Helical Conformation of Poly(phenylacetylene)-based Polyradical
Hiroo KATAGIRI, Takeshi NAMIKOSHI, Edy Marwanta, Masahiro TERAGUCHI, Toshiki AOKI, and Takashi KANEKO*
Center for Transdisciplinary Research, Niigata University
We found that the antiferromagnetic interaction of polyradical 1b was enhanced by the formation of the excess of one-handed helical backbone. The optically active helical polymer 1a was obtained by helix-sense-selective polymerization (HSSP) of the corresponding achiral monomer. The HSSP was promoted by a rhodium complex catalyst in the presence of (R)- or (S)-1-phenylethylamine. The optically active helical conformation was stabilized by intramolecular hydrogen bonding. The chemical oxidation of 1a yielded the corresponding optically active helical polyradical 1b with high spin concentration. The static magnetic susceptibility measurement using a SQUID magnetometer showed the stronger antiferromagnetic interaction for optically active helical polyradical 1b synthesized by HSSP in comparison with the polyradical via polymerization in the presence of racemic phenylethylamine, whose helical conformation could racemize on the intrachain to be random conformation. Polymer Preprints, Japan 2008, 57, 3963.

Single Molecular Imaging of an Intermolecular Interaction as a Hopping Molecular Motion along a Chiral Helical p-Conjugated Polymer Chain
Ken-ichi SHINOHARA
School of Materials Science, Japan Advanced Institute of Science and Technology (JAIST)
The micro-Brownian motion of single molecules in a p-conjugated polymer has been observed before (K. Shinohara et al. Chem. Lett. 2007, 36, 1378). In this study, we succeeded for the first time in the single molecular imaging of a molecular interaction of a chiral helical p-conjugated polymer: (Ð)-poly(MtOCAPA). The flexible molecular motion in which a hopping short chain interacted with a long chain could be observed using a high-speed AFM imaging (9.83 fps) on mica in n-octylbenzene at room temperature. It was found that both chain-ends of the hopping chain interacted easily with another long chain. In the main-chain, a structural wave propagation of the coarse-dense helix was also measured. Polymer Preprints, Japan 2008, 57, 4914.

Click Polyester: Synthesis of Polyesters Containing Triazole Units in the Main Chain
Akinori TAKASU and Yu NAGAO
Department of Frontier Materials, Graduate School of Engineering, Nagoya Institute of Technology
A ÒclickÓ polymerization of diynes that contain ester linkages and diazides has been performed to synthesize various polyesters, termed Òclick polyesterÓs with Mn of 1.0´104 to 7.0´104 in excellent yields. This polymerization is accompanied by a formation of 1,4-disubstituted triazoles in the polyester main chain using Cu(I)Br as the catalyst. The triazole ring formation in the polyester main chain leads not only to improved thermal properties but also to an enhancement of the evenÐodd effect of methylene chain length of the produced Òclick polyesterÓs. This is the first report of the application of ÒclickÓ chemistry to synthesize a series of polyesters under mild conditions. Polymer Preprints, Japan 2008, 57, 2615.

Fabrication of Mechanically Improved Hydrogels Using A Movable Cross-linker Based on Vinyl Modified Polyrotaxane
Yukikazu TAKEOKA
Department of Molecular Design & Engineering, Nagoya University
We have prepared a mechanically improved hydrogel using a novel type of movable cross-linker. We used sparsely dispersed a-CDs threaded into the long polyethylene glycol axle and trapped these with a stable capping agent, 1-adamantanamine, of the polyrotaxane (PR) unit. The OH groups of a-CDs were modified by an isocyanate monomer through the formation of a stable carbamate bond to obtain the polyrotaxane-based cross-linker, MPR. Polymer gels were fabricated by using MPR as a crosslinker and N- isopropylacrylamide (NIPA) as a monomer, which yielded transparent, very soft, flexible and mechanically stable polymer gels. The equilibrium degrees of swelling of the gels give sharp volume changes in water near the lower critical solution temperature of NIPA. The gels exhibit homothetic deformation after a temperature jump above LCST, and the rate of deformation is much faster than conventional poly(NIPA) gel. The softness and mechanical stability of the gels were established using a rheometric solid analyzer. Polymer Preprints, Japan 2007, 56, 1826.

Reversible Chain Transfer Catalyzed Polymerization (RTCP) Ð A New Family of Living Radical Polymerization Making Use of Non-transition Metals as Catalysts
Atsushi GOTO*, Yoshinobu TSUJII, and Takeshi FUKUDA
Institute for Chemical Research, Kyoto University
A new and robust family of living radical polymerizations with germanium (Ge), tin (Sn), phosphorus (P), nitrogen (N), oxygen (O), and carbon (C) catalysts were developed. This is the first living radical polymerization using non-transition metals as catalysts. The catalysts include such common compounds as phosphites (P), imides (N), phenols (O), cyclohexadienes (C), and their iodide derivatives. The polymerizations are based on a new reversible activation mechanism, Reversible chain Transfer (RT) catalysis, and we have proposed to term the related polymerization RT catalyzed polymerization (RTCP). Low-polydispersity polymers with predicted molecular weights were obtained in the homopolymerizations and copolymerizations of styrene and (functional) methacrylates with a fairly high conversion in a reasonably short time. Attractive features of the catalysts include their high reactivity, low toxicity, and low cost. Polymer Preprints, Japan 2008, 57, 2945.

The Electronic Structures and Carrier Conducting Paths of s-Conjugated One-Dimensional Polymers: A Density Functional Theory Study
Hiroshi KAWABATA
National Institute of Science and Technology Policy
Polysilane is one of the s- conjugated one-dimensional polymers and has been extensively investigated because of its potential value as hole and electron transport materials. In the presented study, density functional theory, direct dynamics and crystal orbital overlap population analysis has been carried out in order to determine the electronic structures and conducting paths. For instance, in the case of polysilane with side chain of methyl groups, the hole is delocalized within the Si-Si skeleton, while the penetration of hole in to the side-chain does not take place. Also, the band gap of polysilane is significantly lower in the cationic state. Therefore, the hole is transferred along the Si-Si skeleton under thermal conditions. Namely, in permethyl polysilane, only intramolecular hole transfer is possible, but intermolecular hole transfer is significantly more difficult. For example, J. Organomet. Chem. 2006, 691, 4843. ibid, 2006, 691, 5525., ibid 2007, 692, 1511., J. Chem. Theory and Computation, 2007, 3, 184. etc

Synthesis of Conjugated N-Substituted Maleimide Polymer and Fluorescence Emission of the Obtained Polymers
Kenjiro ONIMURA*, Mieko MATSUSHIMA, Kazuhiro YAMABUKI, and Tsutomu OISHI
Department of Applied Chemistry, Graduate School of Science and Engineering, Yamaguchi University
¹-Conjugated polymers are particularly interesting in the field of electrooptic materials because of their desirable properties such as electrical conductivity, nonlinear optics, and electroluminescence. Coupling-polymerizations of 2,3-dibromo-N-substituted maleimide (DBrRMI) (R=benzyl, phenyl, cyclohexyl, n-hexyl, and n-dodecyl) were carried out using palladium or nickel catalysts. Number-average molecular weights of poly(RMI-alt-Ph) obtained by Suzuki-Miyaura cross coupling-polymerizations of DBrRMI with benzene-1,4-boronic acid or 2,5-thiophene diboronic acid were 680 ~ 1270 by GPC analyses. In contrast, coupling-polymerizations of DBrRMI with diiodobenzene gave random copolymers (poly(RMI-co-Ph)). When exposed to ultraviolet light of wavelength 352 nm, a series of 1,4-phenylene- and/or 2,5-thienylene-based copolymers containing N- substituted maleimide derivatives fluoresced in a yellow to blue color. PMF Preprints, Japan 2008, 17, 52.

Employment of Electrodeposited Polythiophene Films for Low-Cost Production of Organic Thin Film Solar Cells
Yoshihiko TEZUKA*, Hayato INUI, and Hitoshi TANAKA
Institute of Technology and Science, The University of Tokushima
Insoluble and infusible polythiophene (PTh) films were used as the active layer of organic thin films solar cells. The PTh films were deposited directly on PEDOT:PSS-coated ITO electrodes by electropolymerization of unsubstituted thiophene. On the PTh films, a fullerene C60 layer was formed by two kinds of methods, spin-coating and vacuum deposition. An ITO/PEDOT:PSS/ PTh/C60/Al device with the spin-coated C60 layer showed an energy conversion efficiency of 1.2% under laser irradiation of 12 mW/cm2 at 473 nm. This result is one order of magnitude higher compared to that of vacuum deposited C60 only films. The improvement of energy conversion efficiency in the device with the spin-coated C60 layer is ascribed to the porous nature of electrodeposited PTh films. In the process of spin-coating, C60 molecules can permeate into the PTh films in solution to form large PTh/C60 interfaces. Polymer Preprints, Japan 2008, 57, 4351.