No abstract

Enzymatic ring‐opening polymerization of medium‐size lactones, ϵ‐caprolactone (ϵ‐CL) and δ‐valerolactone (δ‐VL), was performed by using a lipase as a catalyst. For the polymerization of ϵ‐CL in bulk, a lipase derived from Pseudomonas fluorescens (lipase PF) showed the highest catalytic activity among the powdery lipases examined, i.e., the highest molecular weight was achieved by using lipase PF. The polymerization behavior depends on the lipase origin as well as on the polymerization condition. From 1H and 13C NMR analyses the polymer was found to possess one terminal carboxylic acid group and one hydroxyl group. δ‐VL was enzymatically polymerized, yielding the corresponding polyester. The polymerization rate of δ‐VL catalyzed by lipase PF is larger than that of ϵ‐CL, whereas the molecular weight of poly(δ‐VL) is lower than that of poly(ϵ‐CL) obtained under similar reaction conditions. The lactones were also enzymatically polymerized in organic solvents. The relationship between the type of the solvent and the polymerization behavior was investigated. An immobilized lipase derived from Candida antarctica causes a much faster polymerization of the lactones than the powdery lipases. The immobilized lipase can be reused as a catalyst for the polymerization of ϵ‐CL.

An immobilized lipase derived from Candida antarctica was used as catalyst for the ring opening polymerization of lactones. A small amount of the immobilized enzyme showed the extremely efficient catalysis in the lactone polymerization. The polymerization in the presence of 1-octanol enhanced the rate of reaction.

Dehydration polymerization of a dicarboxylic acid and glycol proceeded in an aqueous medium by using lipase catalyst to produce an aliphatic polyester. Enzyme origin and the monomer structure affected the yield and molecular weight of the product polyester.

H. Cohn et al. proposed an association scheme of 64 points in R 14 which is conjectured to be a universally optimal code. We show that this scheme has a generalization in terms of Kerdock codes, as well as in terms of maximal collections of real mutually unbiased bases. These schemes are also related to extremal linesets in Euclidean spaces and Barnes-Wall lattices. D. de Caen and E.R. van Dam constructed two infinite series of formally dual 3-class association schemes. We explain this formal duality by constructing two dual abelian schemes related to quaternary linear Kerdock and Preparata codes.