Investigation on the alternating and gradient anionic copolymerization of 4-methylenethiochromane (META) and isoprene modified with additives

A sulfur-containing styrene derivative, 4-methylenethiochromane (META), was subjected to anionic copolymerization with isoprene (Ip) modified with different additives. The reactivity of META can be effectively regulated with additives; thus, gradient and alternating copolymers were prepared in a facile manner. When THF and TMEDA were utilized in the copolymerization, the reactivity was better than that observed without additives, and thus, gradient copolymers with different gradient extents can be synthesized. In addition, metal alkoxides (such as sodium 2,3-dimethylpentan-3-olate (NaODP) and potassium tert -butoxide ( t -BuOK)) were better able to regulate the reactivity, and the copolymers exhibited alternating and nearly alternating sequences. Therefore, the regulation of the alternating or gradient copolymerization of META and Ip was facilely realized through the use of additives.