Synthesis and characterization of functional poly(γ-benzyl-l-glutamate) (PBLG) as a hydrophobic precursor

Four kinds of functional poly(γ-benzyl-l-glutamate) (PBLG) copolymers containing chloro, azido, allyl or propargyl groups on the side chains were synthesized through ester exchange reactions of PBLG with functional alcohols without any protection and de-protection process. Hydrolysis of PBLG, which was found during the ester exchange reaction under low ratios of alcohol to the repeat units of PBLG, was thoroughly investigated, and could be successfully depressed by addition of certain amount of benzyl alcohol to the reaction system. Click chemistry reactions of the azidized or propargylated copolymers, thiol–ene reaction of the allyllated copolymer were taken successfully, indicating that the functional groups on the copolymers were still reactive. Microspheres were also formed, which showed the potential application of the functional polymers as micro-carriers. Characterizations including 1H NMR, 13C NMR, FTIR, elemental analysis, DSC, TGA, ESEM, fluorescence microscope and SEC-MALS were taken.