Synthesis And Self-assembly Of Copolypeptides Based On Poly(γ-benzyl-L-glutamate)

Polypeptide-hybrid block copolymers have the characteristics of polypeptides and block copolymers.The introduction of the alkaline pyridine block can offer more hydrogen bonding interaction,leading to unique self-assembly morphologies.In this paper,ring-opening polymerization of N-carboxyanhydride(NCA-ROP),copper-mediated atom transfer radical polymerization(ATRP)and click reaction were used to synthesize diblock copolymers poly(2-vinylpyridine)-b-poly(γ-benzyl-L/D/DL-glutamate)(P2VP-b-PBL/D/DLG)and poly(4-vinylpyridine)-b-poly(γ-benzyl-L-glutamate)(P4VP-b-PBLG),which were the first examples of diblock copolymer poly(2/4-vinylpyridine)-b-polypeptide combining p H-stimulating P2/4VP with biocompatible and biodegradable PBLG.Gel permeation chromatograph(GPC),proton nuclear magnetic resonance(~1H NMR)and fourier transform infrared spectroscopy(FT-IR)were used to characterize the structures.Then,by using scanning electron microscope(SEM),transmission electron microscope(TEM),atomic force microscopy(AFM)and circular dichroism(CD),self-assembly behaviors of PBLG-b-P2/4VP were studied in this paper.Various self-assembly aggregations were obtained from P2VP-b-PBLG,such as disk,helix and ring etc.After explaining the formation mechanism of each morphology,it proved that the self-assembly morphology of PBLG-b-P2VP could be controlled by regulating the content of methanol and p H values of selective solvent.The chain length and chirality were also studied to interpret the helix structure.On the other hand,dripping speed,chain length,p H values and kind of selective solvent were researched during the self-assembly of P4VP-b-PBLG.This paper also did a comparative analysis on the self-assembly behaviors of P2VP-b-PBLG and P4VP-b-PBLG.