Study on polymeric micelles of poly(γ-benzyl l-glutamate)-graft-poly(ethylene glycol) copolymer and its mixtures with poly(γ-benzyl l-glutamate) homopolymer in ethanol

Poly(γ-benzyl l-glutamate)-graft-poly(ethylene glycol) (PBLG-graft-PEG) copolymer was synthesized by the ester exchange reaction of the PBLG homopolymer with PEG. NMR spectroscopy was used to confirm the composition of the PBLG-graft-PEG copolymer. FTIR spectroscopy was used to characterize the chain conformation of polypeptide segments in the PBLG-graft-PEG copolymer in solid state. The self-assembly behavior of PBLG-graft-PEG and its mixtures with PBLG in ethanol were investigated by transmission electron microscopy (TEM) and viscometry. Experimental results showed that the PBLG-graft-PEG copolymer can self-assemble to form polymeric micelles with a core-shell structure of a thin shuttle-like shape. The introduction of the PBLG homopolymer into the mixed system not only decreases the critical micelle concentration (CMC) but also changes the morphology of the micelles from their shuttle-like shape to cylindrical shape. The effects of test temperature on the critical micelle concentration of PBLG-graft-PEG were also studied.