Carbazyl RAFT agents synthesized by an improved aqueous phase method and their applications in RAFT polymerization

Abstract

A series of carbazyl dithiocarbamates as RAFT agents, i.e. benzyl 9H-carbazole-9-carbodithioate ( B), 1-phenylethyl 9H-carbazole-9-carbodithioate ( C), cumyl 9H-carbazole-9-carbodithioate ( D) and tert-butyl 9H-carbazole-9-carbodithioate ( E), were successfully synthesized by an improved aqueous phase method based on a nucleophilic substitution reaction between sodium carbazole-9-carbodithioate ( A) and alkyl halides at room temperature. Furthermore, the optimum reaction conditions and synthetic technology were sought. Compared with the traditional oil-phase method, the expected high-purity RAFT agents were obtained in the form of crystal that was precipitated and separated from the aqueous solution, so that vast organic solvents for purification were avoided. The activities of the carbazyl dithiocarbamates obtained as RAFT agents for the polymerizations of both styrene and methyl methacrylate were determined. The results show that all of the RAFT agents above mentioned are of significant activity in the RAFT polymerization of styrene, but only D has obvious activity in the RAFT polymerization of methyl methacrylate. Therefore, both the novel synthetic method and the carbazyl dithiocarbamates obtained possess potential application in the RAFT polymerization.