Showing papers by "Yoshiharu Kimura published in 2014"

Protecting-Group-Free Synthesis of Glycopolymers Bearing Sialyloligosaccharide and Their High Binding with the Influenza Virus

Abstract: Glycopolymers having pendant triazole-linked sialyloligosaccharides were successfully synthesized from free saccharides without any protection of the hydroxy and carboxy groups on the saccharides. The glycomonomers were synthesized by the direct azidation of free saccharides using 2-chloro-1,3-dimethylimidazolinium chloride as a condensing agent followed by copper(I)-catalyzed azide–alkyne cycloaddition. The resultant glycomonomers were copolymerized with acrylamide by a reversible addition–fragmentation chain transfer technique. Each of the glycopolymers were obtained and then immobilized on a gold-coated sensor of quartz crystal microbalance to analyze their binding behavior with the lectin. The glycopolymers strongly bound with the corresponding lectin without nonspecific adsorption in aqueous solution. In addition, the glycopolymer bearing a complex-type sialyl N-linked oligosaccharide was found to strongly bind with both human and avian influenza A viruses. The strong binding, observed using the hema...

Nano-Ordered Surface Morphologies by Stereocomplexation of the Enantiomeric Polylactide Chains: Specific Interactions of Surface-Immobilized Poly(d-lactide) and Poly(ethylene glycol)-Poly(l-lactide) Block Copolymers

Abstract: Both AB diblock and ABA triblock copolymers consisting of poly(L-lactide) (PLLA: A) and poly(ethylene glycol) (PEG: B) were deposited on a silicon surface on which poly(D-lactide) (PDLA) had been preimmobilized. The deposit of the diblock copolymer (PLLA-PEG) formed band structures similar to those observed when the same copolymer was directly deposited on the silicon surface. In contrast, the deposit of the triblock copolymer (PLLA-PEG-PLLA) formed many particulates scattering over the surface. When the PLLA-PEG deposit was subjected to water-soaking, the original band morphology was completely replaced by the particulate morphology that was identical to that of the PLLA-PEG-PLLA deposit. Their FT-IR analyses revealed that both copolymers had been bound through the stereocomplex (sc) formation between the preimmobilized PDLA chains and the PLLA blocks of the copolymers. Grazing-incidence small-angle X-ray scattering (GISAXS) also supported these surface morphologies. It was therefore evident that hydrophilic PEG chains can be immobilized on the PDLA-preimmobilized surface by the sc formation.

Preparation of Chain-Extended Poly(hexamethylene carbonate)s and their Block Copolymerization with Poly-L-lactide to Synthesize Partly Biobased Thermoplastic Elastomers

Abstract: An oligomer of poly(hexamethylene carbonate) (PHMC) that is synthesized by ester-exchanging polycondensation of ethylene carbonate and 1,6-hexanediol is chain-extended by using diphenyl carbonate as chain extender. The resultant PHMC, dihydroxyl-terminated, is then subjected to tin-catalyzed ring-opening polymerization of L-lactide to prepare ABA tri-block copolymers consisting of poly-L-lactide (PLLA: A) and PHMC (B), which retain significantly high molecular weights even at increased contents of PHMC. Polymer films of these block copolymers exhibit high elongation, reaching 700% at a high PHMC content. It is therefore suggested that the present block copolymer system can be a novel thermoplastic elastomer, which is partly bio-based.

Protecting-group-free synthesis of glycopolymers bearing thioglycosides via one-pot monomer synthesis from free saccharides

Abstract: Polyacrylamides having pendant thioglycosides were successfully synthesized from thioglycosidic monomers that were readily prepared by one-pot method without any protection of the hydroxy groups on the starting free saccharides. The glycomonomers were synthesized by the direct synthesis of thioglycosides using 2-chloro-1,3-dimethylimidazolinium chloride and 4-aminobenzentiol, and the following acrylamidation. They were co-polymerized with acrylamide into glycopolymers by reversible addition-fragmentation chain transfer polymerization using a trithiocarbonate derivative as a chain transfer agent. The gold nanoparticles and gold-coated quartz crystal microbalance sensor immobilized with the thiol-terminated glycopolymers exhibited high affinity for the corresponding lectins due to multivalent interaction between saccharides and protein in aqueous solution. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 3513–3520

Improved thermal and mechanical properties of poly(butylene succinate) by polymer blending with a thermotropic liquid crystalline polyester

Abstract: A novel polymer blending system consisting of poly(butylene succinate) (PBS) and a thermotropic liquid crystalline polyester [LCP: a poly(4-hydroxybenzoate)-based polymer] was investigated in the presence and absence of a polycarbodiimide (PCD) and/or 1,1′-carbonyl biscaprolactam (CBC) as chain extenders. Although the LCP was immiscible with PBS, it formed elongated fibrous domains having an orientation in the flowing direction when an extensional flow was applied during the processing. Scanning electron micrograph (SEM) of the injection-molded polymer blends supported the distribution of micro fibrils of LCP in the PBS matrix by which the efficient toughening was provided. These blend specimens showed highly improved mechanical properties along with retaining high dynamic storage-moduli (E′) up to the melting temperature of PBS. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39952.