Synthesis and Characterization of Thermally Stable Polymers through Anionic Polymerization of tert-Alkyl Crotonates

Abstract

Some alkyl crotonates bearing tert-alkyl groups, i.e., tert-butyl, tert-amyl, 1-adamantyl and 3,5-dimethyl-1-adamantyl crotonates were prepared and polymerized with sec-butyllithium as an anionic catalyst in toluene or THF. The resulting polymers were confirmed to consist of poly(substituted methylene) structure by IR and NMR spectroscopies. The polymers bearing adamantyl groups had more resistance to hydrolysis, whereas the tert-butyl and amyl esters were readily hydrolyzed. The introduction of the adamantyl groups also increased glass transition temperature and decomposition temperature of the polymer. It was revealed that the polymers bearing the tert-butyl and amyl esters decomposed via a two-step mechanism, resulting in the formation of poly(crotonic acid) accompanied with elimination of corresponding olefins from the ester groups, but the polymers containing adamantyl groups showed excellent thermal stability.