Synthesis and thermoreversible gelation of coil-helical polyethylene-block-poly(γ-benzyl-l-glutamate) diblock copolymer

Abstract

Well-defined coil-helical polyethylene-b-poly(γ-benzyl-l-glutamate) diblock copolymers (PE-b-PBLG) were synthesized by a tandem synthetic strategy combining living polymerization of ethylene and ring-opening polymerization of γ-benzyl-l-glutamate-N-carboxyanhydride (BLG-NCA). Narrowly dispersed hydroxyl-terminated polyethylenes (PE–OH) with high branching density were synthesized by living polymerization of ethylene using an amine–imine nickel catalyst and a transfer agent of ZnEt2 with high efficiency of >90%. Macroinitiator PE–NH2 could be quantitatively obtained by endcapping hydroxyl group of PE with N-tert-butoxycarbonyl-l-valine (BOC-l-valine) and deprotecting BOC group. PE-b-PBLG diblock copolymers were synthesized by subsequent ROP of BLG-NCA. These functional PE materials can form thermoreversible gels by self-assembled nanoribbons in toluene, which will expand the functionality and application of PE based materials.