Synthesis of Graft Copolymers by the Combination of ATRP and Enzymatic ROP in scCO2
journal contributionposted on 26.12.2006, 00:00 by Silvia Villarroya, Jiaxiang Zhou, Kristofer J. Thurecht, Steven M. Howdle
A simple strategy is reported for the synthesis of well-defined graft copolymers of poly(methyl methacrylate-co-2-hydroxyethyl methacrylate) P(MMA-co-HEMA) with poly(ε-caprolactone) (PCL) grafted chains. Using scCO2 as the only solvent, a one-step synthetic approach is adopted to prepare copolymer backbones via atom transfer radical polymerization (ATRP), and grafted chains are added via enzymatic ring-opening polymerization (eROP). Exhaustive study of the enzymatic grafting efficiency showed that only the hydroxyl groups in the backbone initiated the polymerization of ε-CL, resulting in an exceptional polymer architecture which is not accessible by conventional chemical polymerization methodology. The lower grafting density obtained (ca. 30−40%) with the enzymatic polymerization of ε-CL indicates that the system is likely limited by steric hindrance.