The enzymatic degradation and polymerization using an enzyme were carried out with respect to the establishment of a sustainable chemical recycling system for poly(trimethylene carbonate) [P(TMC)] which is a potentially biodegradable synthetic plastic. The enzymatic transformation of P(TMC)s having an M-a of 3000 similar to 48000 using Candida antarctica lipase (lipase CA) in acetonitrile at 70 degreesC afforded the corresponding cyclic monomer, trimethylene carbonate: (TMC: 1,3-dioxan-2-one), in a yield of Up to 80%. Thus Obtained TMC readily polymerized again using both fresh lipase CA and recovered lipase CA.