Synthesis of chain end acyl-functionalized polymers by living anionic polymerization: versatile precursors for H-shaped polymers

Abstract

A series of α,ω-chain end acyl-functionalized polystyrenes with well-defined structures was synthesized by the 1 : 1 addition reaction between 1,1-bis(4-(1-adamantanecarbonyl)phenyl)ethylene (1) and difunctional living anionic polystyrenes prepared with lithium naphthalenide or potassium naphthalenide in THF at −78 °C after capping with 1,1-diphenylethylene (DPE). A tailored ω-functionalized polystyrene was similarly obtained by the reaction of 1 and DPE-capped living polystyrene initiated with sec-BuLi. The DPE-capped polyisoprenyl anion and poly(tert-butyl methacrylate) anion were also effective at preparing tailored end-functionalized polymers by the termination method using 1. The electrophilicity of the CC bond in 1 was significantly enhanced by the electron-withdrawing effect of the 1-adamantylcarbonyl groups on the phenyl rings. The reaction of the living anionic polystyrene or poly(2-vinylpyridine) and the four CO terminal groups in the resulting end-functionalized polystyrene afforded H-shaped (co)polymers possessing well-defined structures. The introduced acyl terminal groups showed high reactivity toward nucleophiles, even in the presence of bulky and stiff adamantyl neighboring groups.