Abstract
The comparison of organolanthanide complexes, (C 5Me 5) 2SmMe(THF) (Sm1) and [(C 5Me 5) 2Sm] 2(PhC C C CPh) (Sm2), with tin compounds, Bu 2Sn(OMe) 2 (Sn1) and Bu 2Sn(OCH 2CH 2CH 2O) (Sn2), in the preparation of random, diblock, and triblock copolymers composed of l-lactide ( l-LA) or d, l-LA and cyclic carbonates, trimethylene carbonate (TMC) or 2,2-dimethyltrimethylene carbonate (DTC) is reported. The biodegradabilities of the resulting copolymers with proteinase K and a compost were examined. The copolymerization of l-LA with cyclic carbonates by Sm1 or Sm2 afforded copolymers with relatively low melting points (<160 °C) due to the accompanying epimerization in comparison with those obtained with Sn1 or Sn2. In the degradation of the polymers with a compost, the copolymers based on d, l-LA were more degradable than those based on l-LA. On the other hand, the effect of the incorporated cyclic carbonate on its degradability was more drastic in the copolymers based on l-LA than those in the copolymers based on d, l-LA. The introduction of only a small amount of the cyclic carbonates into PLLA significantly enhanced the degradability of PLLA with a compost or proteinase K. In the enzymatic degradation of l-LA-containing polymers, the copolymerization of l-LA with TMC was also quite effective to improve the degradability of PLLA. Triblock copolymerization tends to be effective to enhance the degradability of PLLA.
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