Tunable Degradation of Copolymers Prepared by Nitroxide-Mediated Radical Ring-Opening Polymerization and Point-by-Point Comparison with Traditional Polyesters

Two libraries of well-defined, degradable vinyl copolymers of opposite solubility, based either on methyl methacrylate (MMA) or on oligo(ethylene glycol) methyl ether methacrylate (OEGMA), and containing various amount of 2-methylene-4-phenyl-1,3-dioxolane (MPDL), were synthesized by nitroxide-mediated radical ring-opening polymerization. A comprehensive degradation study (long-term hydrolytic degradation, degradation of thick and thin films, water uptake, enzymatic degradation) was then performed, and results were compared with those from traditional aliphatic polyesters (PLGA, PLA, and PCL). It appeared that P(MMA-co-MPDL) copolymers slowly degraded in PBS with degradation kinetics slower than that of PCL whereas P(OEGMA-co-MPDL) copolymers led to significant degradation, in between that of PLA and PCL, depending on the amount of MPDL, but without leading to a dramatic drop of pH as for PLGA and PLA. Whereas P(MMA-co-MPDL) copolymers might be well-suited for biomaterials intended for long-term use (e.g., devices and implants), faster degrading P(OEGMA-co-MPDL) copolymers might be envisioned for short- or midterm applications such as nanoscale drug-delivery systems, meeting a need for hydrophilic degradable materials with tunable degradation kinetics.