The last challenge for living anionic polymerization of 1,3-cyclohexadiene with the s-butyllithium/cyclopentyl methyl ether system

A well-controlled anionic polymerization of 1,3-cyclohexadiene (1,3-CHD) with the alkyllithium (RLi)/ether system has been achieved for the first time. The type of ether was the predominant factor affecting the polymerization results. Optimization of the nucleophilicity and solubility of the initiator (system) and propagating species was also important for the polymerization reaction. An initiator system of sec-butyllithium (s-BuLi)/cyclopentyl methyl ether (CPME) in toluene was found to be very effective for forming well-controlled polymer chains of poly(1,3-CHD), and living anionic polymerization was achieved. In this system, the polymer chains mainly consisted of 1,4-cyclohexadiene (1,4-CHD) units. It was confirmed that the s-BuLi/CPME system was a new example of living anionic polymerization of 1,3-CHD.