Study of impregnation of poly(L-lactide-ran-ε-caprolactone) copolymers with useful compounds in supercritical carbon dioxide
2009
Tsutsumi, Chikara | Sakafuji, Jun | Okada, Mai | Oro, Kazuyuki | Hata, Kazuaki
Outstanding controlled release materials were developed using statistically random copolymers of L-lactide (L-LA) with ε-caprolactone (CL) using Sn(oct)₂ as a catalyst at 150 °C for 24 h without solvent. Preparation of novel controlled release materials was carried out using useful organic compounds with low boiling points and synthetic random copolymers composed of L-LA and CL as base materials under supercritical carbon dioxide (scCO₂). Low-boiling-point compounds such as d-limonene, hinokitiol, and trans-2-hexenal were used. In impregnation experiments using scCO₂, the amounts of low-boiling-point compounds increased with an increase in L-LA content. When enzymatic degradation of poly(L-LA-ran-CL) was performed using lipase PS, copolymers with higher CL contents degraded more rapidly than did copolymers with higher L-LA content. In contrast, enzymatic degradation of copolymers occurred to a higher degree with increased L-LA content in enzymatic degradation by proteinase K. In a controlled release experiment with poly(L-LA-ran-CL) (=73/27), after 400 h of degradation by proteinase K, the remaining weight of the copolymer pellet was 6% and the amount of d-limonene remaining in the pellet was 15%.
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