Organic Brnsted Acid-Catalyzed Ring-OpeningPolymerization (ROP) of Cyclic Esters

초록

We reported the first study of organocatalytic ring-opening polymerization (ROP) of phenyl-substituted caprolactone with two different positions on lactone ring, ?-Phenyl- ?-caprolactone (?-PhCL) and γ-Phenyl- ?-caprolactone (γ-PhCL), and their copolymerization with L-LA. Diphenyl phosphate (DPP), weak acid, low toxicity, and chemically available, was investigated as a potential effective acid-type organocatalyst. Changing the substituent position from ?- to γ-position is faster than that of ε-PhCL polymerization without effect of transesterification. The structure of copolymer between PγPhCL and PLLA were confirmed by FTIR with the absorption at 2900, 1750 and 700-760 cm-1 for CH and CH2, carbonyl and phenyl group, respectively. In addition, Tm of PγPhCL shows at 56 ℃ and 2 melting peaks of PLLA can be observed between 144 to 157 ℃.