Polymers - Vol. 58, No. 7 (July, 2009)

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Vol. 58, No. 7 July,( 2009)

Microbial Production of Lactate-Based Polyesters
Ken'ichiro MATSUMOTO*, Miwa YAMADA, Takanori NAKAI, and Seiichi TAGUCHI
Division of Biotechnology and Macromolecular Chemistry, Graduate School of Engineering, Hokkaido University

We constructed a one-step bioprocess producing lactate (LA)-based polyesters from renewable biomass. Our recent finding of an engineered LA-polymerizing enzyme enabled us to omit the chemical polymerization process of LA with heavy metal catalysts. LA-based polyesters are enantioselectively synthesized as copolymers with 3-hydroxybutyrate (3HB). They are extracted and processed into useful bio-based plastic products. The new bioprocess, "microbial factory", has a potential to be an environmentally and human friendly alternative to the conventional method. Polymer Reprints, Japan 2009, 58, 2062.

Control of Arrangement for s-Triazine Group in Comb Copolymers by Langmuir-Blodgett Method and Its Structural Estimation by NEXAFS Spectroscopy
Atsuhiro FUJIMORI
Yamagata University
The control of orientation for 2-vinyl-4, 6-diamino-1, 3, 5-triazine in monolayers for newly synthesized comb copolymers is investigated by co-polymerization with fluorinated long-chain vinyl compounds and Langmuir-Blodgett methods. Since diamino-s-triazine has adsorption ability to an adenine-thymine base pair of a DNA molecule, the control of orientation for s-triazine makes it possible to construct candidates of new biochip materials. As a result, changes in the two-dimensional lattice of fluorinated copolymer films containing s-triazine, in contrast to their bulk state, were confirmed. Structural change is caused by ƒÎ-ƒÎ interaction between the s- triazine rings rather than van der Waals interaction between fluorocarbons. Polarized NEXAFS spectroscopy showed highly ordered orientation of s-triazine. These findings relate to well-ordered arrangement of functional groups supporting the side-chain rearrangement caused by ƒÎ-ƒÎ interaction between the s-triazine rings. Polymer Preprints, Japan 2008, 57, 3180.

Anionic Polymerization of Methyl Methacrylate in an Ionic Liquid
Hisashi KOKUBO
Department of Chemistry and Biotechnology, Yokohama National University
Anionic polymerization reactions of methyl methacrylate (MMA) in 1-butyl-3-methylimidazolium hexafluorophosphate, [C4mim][PF6], were carried out by using alkyl lithium initiators such as diphenylhexyl lithium. The tacticity of the obtained PMMA was rich in mm triads, similar to that polymerized in toluene. [C4mim][PF6] consists of a soft Lewis acidic imidazolium cation and a soft Lewis basic PF6- anion. In [C4mim][PF6], the propagation end of the PMMA is not entirely dissociated as that in THF but forms a coordination structure similar to that in toluene, because a hard Lewis acidic lithium cation has a stronger affinity toward a carbanion as compared to a soft Lewis basic PF6- anion. Thus, it is presumed that the obtained PMMA prepared in [C4mim][PF6] has an isotactic-rich structure. Polymer Preprints, Japan 2008, 57, 511.

Creation and Evaluation of Optical Properties of Organic-Inorganic Semiconductor Heterostructures using ƒÎ-Conjugated Polymers
Yuko TAKEOKA*, Yukimi KAWABATA, Masahiro FUJITA, and Masahiro RIKUKAWA
Department of Materials and Life Sciences, Sophia University
Organic-inorganic perovskites have recently attracted great attention because these compounds may combine useful properties of inorganic and organic moieties at molecular scale crystalline composites. By changing molecular structures of the inorganic and organic components, a variety of readily processable hybrid perovskites have been fabricated. Some of the products have been found to exhibit interesting physical properties such as tunable exciton absorption and efficient light emission. A recent trend in this field of hybrid materials is to incorporate molecules with lowered HOMO-LUMO gap such as extended ƒÎ-conjugated systems, which can combine semiconducting properties and luminescent, or nonlinear optical properties into the organic layers. We tried to incorporate various functional organic moieties such as polydiacetylene, oligothiophene, and fullerene derivatives into the organic-inorganic perovskites. By incorporating ƒÎ-conjugated molecules into the organic-inorganic perovskites, interaction between inorganic and organic layers were observed in photoluminescence spectroscopy and photoconductivity measurements. This suggested that the layered perovskite compounds containing ƒÎ-conjugated molecules provide high optoelectrical activity and are applicable to organic photovoltaic cells. Synthetic Metals, Japan 2009, 159, 776.

Precision Structural Analysis and its Application to Biomaterials of Silks
Yasumoto NAKAZAWA
Graduate School of Engineering, Tokyo University of Agriculture and Technology
Solid state NMR has been successfully used for structural determination of silk fibroins from which it is difficult to obtain single crystals. The structure of the silk fibroin from wild silkworms, Samia cynthia ricini and the domestic silkworm, Bombyx mori, were determined. For this purpose, several solid state NMR methods were used for the structural analysis of several stable-isotope labeled model peptides from silk fibroins. Moreover, the structure of ƒÀ-amyloid peptide from Alzheimer's disease was also determined. The reason to use the latter was the fact that the ƒÀ-sheet formation in silk fiber assembly shows structural similarities to cross-ƒÀ sheet formation in the amyloid fibril assembly. These structural information of silk fibroins will be applicable for development of new biomaterials based on the silks, such as vascular grafts, bones and wound dressing made for tissue engineering. Polymer Preprints, Japan 2008, 57, 4461. Polymer Preprints, Japan 2008, 57, 5136. Polymer Preprints, Japan 2008, 57, 5162. Polymer Preprints, Japan 2008, 57, 4783. Polymer Preprints, Japan 2009, 58, 1835. Chem. Phys. Lipids 2009, 158, 54.

Click-Type Reaction of Aromatic Polyamines
Tsuyoshi MICHINOBU
Global Edge Institute, Tokyo Institute of Technology, and PRESTO, JST
Click-type reaction between electron-rich alkynes and tetracyanoethylene (TCNE), yielding the donor-substituted 1,1,4,4-tetracyanobuta-1,3-diene chromophores, was found to be a powerful tool in the improvement of thermal and optoelectronic properties of aromatic polyamines. The fluorene-based aromatic polyamines bearing electron-rich alkyne side chains were reacted with TCNE at room temperature, resulting in an immediate color change from yellow to red. The presence of the isosbestic point in the UV-Vis spectral change indicated the absence of any undesired side reactions and MALDI-TOF MS spectra provided evidence for a quantitative addition reaction. With increasing amount of the TCNE added, a linear decrease in LUMO level and a gradual increase in decomposition temperature were observed. Polymer Preprints, Japan 2008, 57, 3929.

π-Electronic Spiral Stairways by Self-Assembly
Yohei YAMAMOTO
JST ERATO-SORST
Synchrotron radiation X-ray diffraction studies revealed that Gemini-shaped hexa-peri- hexabenzocoronene (HBC) derivatives stack like a spiral stairway to form nanotubular assemblies. According to a two-dimensional diffraction image (Fig. 1a) observed for a macroscopic fiber composed of unidirectionally aligned HBC nanotubes, the HBC units stacked on top of each other and were oriented perpendicular to the longer axis of the tube (Fig. 1b). The ƒÎ-stacked columnar arrays of the HBC molecules grow helically, where the central axes of the HBC columns are tilted by 45‹relative to the longer axis of the tube. The ƒÎ-electronic spiral stairway of the HBC units potentially serves as a helical conduction pathway. J. Am. Chem. Soc. 2008, 130, 9434. Adv. Mater. 2006, 18, 1297.

Design of Novel Polymer-Supported Chiral Catalysts for Asymmetric Reactions in Aqueous Media
Naoki HARAGUCHI
Department of Materials Science, Toyohashi University of Technology
Novel polymer-supported chiral catalysts functionalized with a sulfonic acid quaternary ammonium salt were designed for catalytic asymmetric reactions in aqueous media. The hydrophilic-hydrophobic balance of polymer-supported chiral catalysts could be controlled by combination of the sulfonate and quaternary ammonium groups. Higher reactivity and enantioselectivity of the chiral product were observed in asymmetric transfer hydrogenation of aromatic ketones in neat water probably due to the suitable chiral microenvironment formed by the polymer-supported chiral catalyst. In addition, novel monomers with chiral quaternary ammonium salts were readily polymerized to give polymer-supported chiral quaternary ammonium salts. The resulting polymeric organocatalysts showed efficient catalytic activity and could be reused several times without loss of the activity. Polymer Preprints, Japan 2008, 57, 4061.

Supramolecular Single-Walled Carbon Nanotube Materials Utilizing Macrocyclic Host Compounds
Tomoki OGOSHI1*, Tada-aki YAMAGISHI1, Yoshiaki NAKAMOTO1, and Akira HARADA2
1Graduate School of Natural Science and Technology, Kanazawa University 2Graduate School of Science, Osaka University
We have developed hybrids of single-walled carbon nanotubes (SWNTs) and macrocyclic host compounds such as cyclodextrins, cyclodextrin-guest complexes, water-soluble calixarenes and cucurbiturils. Since these macrocyclic hosts form host-guest complexes with various kinds of guests, cavities of the macrocycles around SWNT are able to capture guest molecules on SWNT surface. By utilizing host-guest interaction between b-CDs on SWNT surface and polymers carrying guest moieties, supramolecular SWNT hydrogels were successfully prepared. The supramolecular SWNT hydrogel exhibited gel to sol transition by adding competitive guest and host. Moreover, by using the hybrids of water-soluble calixarenes and SWNTs, supramolecular polymers comprised of SWNTs were constructed. Polymer Preprints, Japan 2007, 56, 2646. Polymer Preprints, Japan 2008, 57, 611.

Supramolecular Polymerization Catalyst: Activation of Monomer in the Molecular Recognition Site
Yoshinori TAKASHIMA
Graduate School of Science, Osaka University, Department of Macromolecular Science
Cyclodextrins (CDs) selectively initiate polymerizations of some lactones to give polyesters with a single CD molecule at the end of a polyester only by mixing CD and lactones. No co-catalysts and solvents were required to polymerize lactones by using CDs as an initiator. It should be noted that poly-pseudo-rotaxane incorporating polyester with a CD showed the polymerization activity, whereas only the polyester with a CD did not have the polymerization ability for lactones. These processes are similar to those of chaperone proteins in biological systems, which assist protein folding and allow the functional state of proteins. CDs showed not only the activation and transformation of a monomer like an enzyme, but also protein-like refolding activity as an artificial chaperone. J. Am. Chem. Soc. 2007, 129, 14452. Kobunshi Ronbunshu 2007, 64, 607. J. Am. Chem. Soc. 2004, 126, 13588.

Single-Photon Emission from a Single Conjugated Polymer Chain by Controlling its Spatial Size
Sadahiro MASUO
Department of Macromolecular Science and Engineering, Kyoto Institute of Technology
Single-photon sources capable of emitting only one photon at any point in time have been intensively investigated for quantum information processing. Generally, multi-chromophoric systems consisting of many chromophores, such as emissive conjugated polymer chains cannot behave as single-photon sources. However, we have revealed that the emission from such single conjugated polymer chains can be made to behave as single-photon sources by controlling their size, that is, molecular weight (MW) and conformation. The probability of single-photon emission from the single chains increases with decreasing MW, and when the polymer chains adopt the "collapsed" conformation, this probability is larger than for the "extended" conformation. Polymer Preprints, Japan 2008, 57, 4459.

Macroscopic Pattern Formation of Liquid Crystal in Polysaccharide Gel
Takayuki NARITA
Department of Chemistry and Applied Chemistry, Saga University
rod-shaped gel, having crystals that form a macroscopic pattern, is obtained when potassium ions diffuse into a glass capillary that contains a ƒÈ-carrageenan (a polysaccharide made from a type of seaweed) solution. Though the gel is almost transparent under natural light, a striped pattern perpendicular to the direction of the diffusion of potassium chloride appears within the gel when observed under crossed Nicols. The period and thickness of stripes, which are layers of liquid crystalline gel, depend critically on the concentration of the potassium chloride solution. Langmuir 2006, 22, 349.