| 摘要 |
PURPOSE: To obtain a new high-strength ester-carbonate block copolymer having excellent biodegradability, hydrolysis, high molecular weight and high melting point by subjecting an optically activeβ-butyrolactone and a cyclic carbonate to ring opening polymerization. CONSTITUTION: This copolymer comprises structural units of formula I and formula II (R<1> to R<4> are each H or methyl; (m) and (n) are natural numbers of 300-5,000). The copolymer has the ratio of the unit I:II of (10-90):(90-10) and 100,000-500,000 weight-average molecular weight. The copolymer is obtained by subjecting an optically activeβ-butyrolactone and a cyclic carbonate (e.g. trimethylene carbonate) to successive ring opening polymerization in the presence of a catalyst. A distannoxane of formula III (R<5> is a 1-12C alkyl or phenyl; X is Cl or Br; Y is Cl or phenoxy) such as 1,3-dichlorotetrabutyldistannoxane is preferably used as the catalyst.
|
