New chitin-based polymer hybrids, 1. Miscibility of poly(vinyl alcohol) with chitin derivatives

As a new class of biopolymer-based hybrid materials, the present paper describes the binary blends of a modified chitin and poly(vinyl alcohol) (PVA) which are miscible in the whole range of compositions. The blend films were prepared by the solvent cast method from a homogeneous aqueous solution of PVA and a chitin derivative having poly(2-methyl-2-oxazoline) side chains. Miscibility between PVA and poly(2-methyl-2-oxazoline) homopolymer was also revealed. Differential scanning calorimetry and FT-IR analyses were used to investigate the blends.     

Polymerization chemistry of the family of cyclic imino ethers

Characteristics of the polymerization mechanisms of the family of cyclic imino ethers are described. The variety of the mechanism of propagation has been systematized on the basis of the nature of propagating species, i.e., cationic or electrophilic covalent (dipole) species. In the polymerizations of 2-alkyl cyclic imino ethers (5- and 6-membered), propagation mechanism via one of these two different species has been established, which is dependent upon the relative nucleophilic reactivities of the monomer and the counter anion derived from initiator. The polymerization of cyclic pseudoureas having a cyclic amine substituent at 2-position proceeds in two different ways. Ionic propagation leads to the single isomerization/ring-opening polymerization involving only the cyclic imino ether ring. On the other hand, covalent propagation gives rise to the double isomerization ring-opening polymerization involving the two rings of cyclic imino ether and cyclic amine. Polymerization of 5-membered cyclic iminocarbonate with a sulfonate initiator proceeds through the isomerization/ring-opening of 2-oxazoline ring. The same monomer was isomerized to the corresponding cyclic urethane when it was treated with benzyl bromide.     

Aggregate of a peptide-containing block copolymer with a lipase

The peptide-containing block copolymer poly(N-acetyliminoethylene)-block-poly(L -phenylalanine) (1) formed large water-soluble aggregates in water due to the hydrophobic and hydrogen-bonding character of the poly(L -phenylalanine) block. The solution properties of 1 were compared with those of the block copolymer poly(N-acetyliminoethylene)-block-poly(N-benzoyliminoethylene) (2) with an analogous structure. 1 formed aggregates even though the poly(phenylalanine) segment was short as compared with 2 in which hydrophobic interaction may be the only driving force to form aggregates. The aggregates have strong capability of incorporating Lipase P and largely increase the hydrolysis activity against p-nitrophenyl propionate as compared with that of free Lipase P.