Phosphonoethylated Polyglycidols: A Platform for Tunable Enzymatic Grafting Density

Polyether graft polyester copolymers with pendant diethylphosphonatoethyl groups (DEPE), P(GDEPE-co-(G-g-eCL)-co-G), were prepared by enzymatic grafting of e-caprolactone from polyglycidols carrying 0, 15.4, and 38.5% of DEPE groups. The graft copolymers were characterized by 1H, 13C, and 31P NMR spectroscopy and SEC analysis. Despite the steric bulk of the DEPE residues, high initiation efficiencies (IE) of the phosphonoethylated macroinitiators could be achieved by appropriate choice of the reaction parameters such as lipase and monomer concentration. Depending on the degree of functionalization of polyglycidol with phosphonate residues (FDEPE), the IE is tunable in a wide range from 31 to 81%. The graft copolymers with pendant phosphonate groups are promising candidates for hydrolytically degradable biomaterials, since all building blocks are biocompatible and/or biodegradable.