Toshikazu Kurosaki

Improved blood compatibility of segmented polyurethane by polymeric additives having phospholipid polar group. II. Dispersion state of the polymeric additive and protein adsorption on the surface

To improve the blood compatibility of a segmented polyurethane (SPU), phospholipid polymer, i.e., 2-methacryloyloxyethyl phosphorylcholine (MPC) copolymerized with cyclohexyl methacrylate or 2-ethylhexyl methacrylate, was blended into SPU as a polymeric additive. The blending was achieved by a solvent-evaporation technique from a homogeneous solution containing both the SPU and the MPC polymer. Surface analysis of the SPU membrane blended with the MPC polymer (SPU/MPC polymer membrane) revealed that the MPC polymer was concentrated at the surface of the SPU membrane which contacted the substrate, Teflon, compared with that which contacted air during the membrane-formation period. The dispersion state of the MPC polymer in the SPU membrane was evaluated in detail by staining the MPC unit with osmium tetraoxide. When sonication was applied during preparation of the mixed solution containing SPU and the MPC polymer, the dispersion of the MPC polymer in the SPU membrane was different from that without sonication. That is, the size of the domains of the MPC polymer became smaller but the number of the domains increased. The amount of the MPC polymer mixed with SPU affected the dispersion state. Plasma proteins adsorbed on the SPU/MPC polymer membrane surface after contact with human plasma were detected by gold-colloid-labeled immunoassay. Both albumin and fibrinogen were observed on the SPU membrane; however, the amount of these proteins was reduced on the SPU/MPC polymer membrane. Thus it was concluded that the blood compatibility of the SPU was effectively improved by the blending of the MPC polymer.

Optically active N-hydroxytartrimides for enantioselective peptide synthesis

Abstract Preparations of optically active N-hydroxytartrimides were achieved. 1,3,4-Trihydroxysuccinimide ester of Z-L-alanine and 1-hydroxy-3,4-diacetoxysuccinimide ester of Z-D-alanine were allowed to react with D,L-alaninate to produce L-L form and D-D form of Z-Ala-Ala-OEt respectively (optical yield 100%).

Synthesis and Properties of New Naphthyl-Pendent Aromatic Polyimides from 1-[di(4-aminophenyl)Aminojnaphthalene and Aromatic Tetracarboxylic Dianhydrides

New naphthyl-pendent aromatic polyimides having inherent viscosities of 0.40-0.93 dl g-1 were synthesized from 1-[di(4-aminophenyl)amino]naphthalene and various aromatic tetracarboxylic dianhydrides by the conventional two-step procedure that included ring-opening polyaddition giving polyamic acids and subsequent thermal cyclodehydration. Almost all of the naphthyl-pendent polyimides were readily soluble on heating in organic solvents such as N-methyl-2-pyrrolidone, dimethyl sulfoxide, and m-cresol. Some polyimides gave flexible and tough films with good tensile properties. The glass transition temperatures and 10% weight loss temperatures of the polyimides were in the ranges of 297-319 0C and 530-560 0C, respectively, in nitrogen.

Preparation and Properties of Aliphatic Polybenzoxazoles from 4,4′-Diamino-3,3′-Dihydroxybiphenyl and Aliphatic Dicarboxylic Acid Chlorides by the Silylation Method

Abstract A series of aliphatic polybenzoxazoles of high molecular weights was prepared in three steps by the low-temperature solution polycondensation of tetrakis(trimethylsilyl)-substituted 4,4′-diamino-3,3′-dihydroxy-biphenyl with aliphatic diacid chlorides with 7 to 12 methylene units yielding trimethylsilyl-substituted poly(o-hydroxysamide) precursor polymers, which were subjected to desilylation with methanol giving the poly(o-hydroxyamide)s, followed by thermal cyclodehydration. The aliphatic polybenzoxazoles had melting points in the 172 to 246 °C range with glass transition temperatures of 55-97°C. They were stable in the melt state up to 400 °C in nitrogen. These polybenzoxazoles and the corresponding bisbenzoxazole model compounds exhibited no liquid crystallinity.