Functional Degradable Polymers via Radical Ring-Opening Polymerization and Click Chemistry

The use of free-radical polymerization for the formation of an alkyne-functionalized polymer with ester units of polycaprolactone type in the backbone is shown. This is done by the copolymerization of a cyclic ketene acetal [2-methylene-1,3-dioxepane (MDO)] with propargyl acrylate using a free radical initiator, azobis(isobutyronitrile). Structural characterization of the copolymers using 1D and 2D NMR techniques shows the random distribution and very high percentage of inclusion of alkyne groups onto the polymer backbone. The exemplary grafting of a biocompatible polymer [poly(ethylene glycol)] via azide-alkyne click chemistry is also shown. Hydrolytic degradation behavior and biocompatibility of the polymers (cytotoxicity) studies are also reported.