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.