Sugar-Installed Polymer Micelles: Synthesis and Micellization of Poly(ethylene glycol)−Poly(d,l-lactide) Block Copolymers Having Sugar Groups at the PEG Chain End

Abstract

A poly(ethylene glycol)−poly(d,l-lactide) block copolymer (PEG−PLA) having a site specifically protected-sugar group at the PEG chain end was synthesized through a successive ring-opening polymerization of ethylene oxide and d,l-lactide using a metalated protected sugar as an initiator. Removal of protective groups from the sugar residue in the block copolymer was quantitatively carried out using 80% trifluoroacetic acid at room temperature, yielding a block copolymer having a glucose or galactose residue at the chain end in a regioselective manner. Polymer micelles having sugar residues on the surface were then prepared by dialyzing an N,N-dimethylacetamide solution of the sugar-bearing PEG−PLA block copolymer against water. Dynamic light-scattering measurement of the polymer micelle solution revealed that the scaled characteristics line width had essentially no angular dependence, consistent with the spherical geometry of the polymer micelle. The diameter and polydispersity index of the polymer micelle,...