Synthesis and characterization of anionic polymerization initiator from functional styrene derivative

Abstract

Understanding the mechanisms underlying living anionic polymerization is essential for advancing efficient and sustainable elastomer production technologies. This study investigates the introduction of a functional styrene derivative at the initiation of a styrene-butadiene polymer chain with high efficiency. Butyllithium is the most widely used initiator in anionic polymerization due to its high reactivity, availability, and ability to provide precise control over polymer molecular weight and structure. Modified initiators, formed from N-(dimethyl(vinylbenzyl)silyl)-N,N-bis(trimethylsilyl)amine and isomers of butyllithium (n-, sec-, and tert-), increase initiation efficiency and reduce oligomer formation. The developed procedure demonstrates the effective use of a functional styrene derivative as an alpha chain-end modifier. The formation of a unimeric structure improves from 15.6% to 88.3%, significantly increasing the yield of alpha functionalization. Direct transfer of the functional styrene derivative to the alpha position expands the potential for functionalization in anionic polymerization. The activity of the preinitiators is evaluated in styrene-butadiene anionic copolymerization. The functional initiators are terminated and characterized by high-performance liquid chromatography coupled with gel permeation chromatography to assess the degree of polymerization. This method enables quantitative analysis of oligomer formation. The synthesized copolymers are further characterized by their molar masses, microstructure, Mooney viscosity, and glass transition temperature.