Synthesis and Radical Polymerization of a Novel Macromonomer Obtained by Living Cationic Ring-Opening Polymerization of an Optically Active Cyclic Thiourethane by a New Initiator Carrying Styryl Group

摘要

A new cationic initiator,4-vinylbenzoic acid 2-methylsulfanyl-4,5-dihydrooxazolinium-4-ylmethyl ester trifluoromethanesulfonate (1),carrying both vinyl and triflate groups,was synthesized in quantitative yield by reaction of l,3-oxazolidine-2-thione derivative with methyl trifluoromethanesulfonate.Living cationic ring-opening polymerization of an optically active cyclic thiourethane (SL) derived from L-serine was carried out by with 1 as an initiator in dichloromethane to give the corresponding macromonomers (MSL;M_n>10~4,M_w/M_n<1.18),and the molecular weight of MS_L could be controlled by [SL]/[1].MSL consists of the optically active thiourethane main chain and styryl group in the initiating end quantitatively.The radical homopolymerization of MSL and the copolymerization with styrene were carried out to obtain the corresponding polymers in higher yields.The obtained polymer from MSL showed higher specific rotation ([alpha]~(25)_D),melting point (T_m),and Cotton effect than MSL,supporting the stabilized secondary structure of grafted poly(SL) side chain.