A robust strategy for the synthesis of miktoarm star copolymers by combination of ROP and photoinitiated free radical polymerization

A novel approach for the synthesis of miktoarm star copolymers by the combination of ring opening polymerization (ROP) and Type II photopolymerization is described. The method pertains to the use of a multifunctional initiator, bearing primary hydroxyl and tertiary amine functionalities, for the sequential or simultaneous polymerization of vinyl and lactone monomers under mild conditions. In the first step, phosphazene base (P-2-t-Bu) catalyzed ROP of epsilon-caprolactone is accomplished. Subsequently, thus obtained poly(epsilon-caprolactone) with amine end groups was used as co-initiator for the polymerization of methyl methacrylate by utilizing conventional Type II photoinitiators. The structures, molecular weight characteristics and thermal properties of the polymers are analyzed by NMR, gel permeation chromatography (GPC) and differential scanning calorimetry (DSC) measurements, respectively.