Synthesis of Novel Amphiphilic Block Copolymers of Poly-N-vinylpyrrolidone and Poly (D, L-lactide) by Atom Transfer Radical Polymerization

In order to improve the hydrophilicity of poly (D,L-latide) (PDLLA), a novel amphiphilic ABA-type triblock copolymers of poly-N-vinylpyrrolidone (A) and poly (D, L-lactide) (B), were successfully synthesized by atom transfer radical polymerization (ATRP) using N-vinylpyrrolidone (VP) as monomer, bromide-terminated poly (D,L-latide) oligomer (Br-PDLLA-Br) as functional macromolecular initiator which was prepared when hydroxy-terminated poly(D,L-latide) oligomer (HO-PDLLA-OH) reacted with 2-bromopropanoyl bromide, CuBr/2,2’-bipyridine complex as the catalyst system. The resulting copolymers were characterized by various analytical techniques. The results showed that the introduction of poly (N-vinylpyrrolidone) (PVP) segments into polylactide enhanced the surface hydrophilicity of the copolymers remarkably and amphiphilic polymer can self-assemble into core-shell structure (polymer micelle) in water by the balance of the hydrophilic and hydrophobic interaction.