Precise Synthesis of Bottlebrush Block Copolymers from ω-End-Norbornyl Polystyrene and Poly(4-tert-butoxystyrene) via Living Anionic Polymerization and Ring-Opening Metathesis Polymerization

摘要

A facile and efficient synthetic grafting-through strategy for preparing well-defined bottlebrush block copolymers (BBCPs) was developed through a combination of living anionic polymerization (LAP) and ring-opening metathesis polymerization (ROMP). ω-End-norbornyl polystyrene (NPSt) and poly(4- tert -butoxystyrene) (NP t BOS) were synthesized by LAP using terminator of chlorine moiety containing silane-protecting amine and coupled with a subsequent amidation using norbornyl activated ester. Bottlebrush homopolymers of NPSt were obtained by ROMP with ultrahigh molecular weights (MWs, M _(w) = 2928 kDa) and narrow molecular weight distributions (MWDs, ? = 1.07) at high degree of polymerizations (DP_(w) = 1084). Well-defined BBCPs with ultrahigh MWs ( M _(w) ～ 3055 kDa) and narrow MWDs ( ? ～ 1.13) were synthesized through sequential ROMP of NPSt with NP t BOS. The effect of ultrahigh MWs was investigated by self-assembly of the BBCPs in which the phase-separated BBCPs presented periodic lamellar structures and exhibited structural colors from blue to pink.