Enzymatic Ring-Opening Polymerization of Trimethylene Carbonate with Macrodiol: Synthesis of Block Poly(ester-co-carbonate) for Biomaterial Preparation

Novozym 435-catalyzed ring-opening polymerization (ROP) of trimethylene carbonate (TMC) with telechelic hydroxylated poly[(R)-3-hydroxybytyrate][PHB-diol; M(n) = 3000 g/mol (GPC)] as initiator gave di-block poly(HB-co-TMC) with different weight percents of the blocks and M(n) of 4400-8700 g/mol (GPC) in 54-89% yield, being the first enzymatic preparation of block poly(ester-co-carbonate). The generality of the novel enzymatic method was demonstrated by the enzymatic ROP of TMC with poly(epsilon-caprolactone)-diol [PCL-diol; Mn of 4200 g/mol (GPC)] to give A-B-A tri-block-poly(TMC-co-CL-co-TMC) with different weight percents of the 67% yield. The prepared block poly(ester-co-carbonate) with two terminal hydroxyl groups was proven to be a useful starting material for the further preparation of thermoplastic block copolymers. Polymerization of di-block poly(24 wt % HB-co-76 wt % TMC) with methylene diphenyl-4-4'-diisocyanate (MDI) afforded the corresponding polyurethane with M(n) of 53 800 g/mol (GPC) in 94% yield. The polymer showed excellent thermoplastic properties (T(m) of 144 and 152 degrees C, T(g) of -9 degrees C, epsilon(b) of 252%, sigma(max) of 6.37 MPa, and E of 23 MPa), being potentially useful for soft tissue engineering.