Synthesis and characterization of epoxy-chain end(s) functional macromonomer of polystyrene and its use in photoinitiated cationic polymerization

摘要

A novel epoxy chain-end(s) functional polystyrene macromonomer (PSt-CHO) was prepared via free radical polymerization (FRP) of styrene (St) initiated by 4,4'-azobis(3-cyclohexenylmethyl-4-cyanopentanoate) (ACCP) azo initiator and epoxidation on workup with 3-chloro-peroxybenzoic acid under inert atmosphere in methylene chloride at 0 ℃. 4,4'-Azobis(4-cyanopentanoyl chloride) (ACPC) was obtained by the reaction of 4,4'-azobis(4-cy-anopentanoic acid) (ACPA) with phosphorus pentachloride in methylene chloride. The ACCP was synthesized by the condensation reaction of 3-cyclohexene-1-methanol with ACPC. The FRP of styrene with ACCP has yielded polystyrene with cyclohexene end(s) group (PSt-CH). Epoxidation of the PSt-CH was performed using 3-chlo-roperoxybenzoic acid to obtain epoxy chain-end(s) functional polystyrene macromonomer (PSt-CHO). This macromonomer was used as precursor in photoinitiated cationic polymerization for obtaining brush-type and graft copolymers. Photoinitiated cationic homopolymerization of the macromonomer in the presence of diphenyliodonium salt at λ = 300 nm yielded brush-type polymers. Photoinitiated cationic copolymerization of the macromonomer with cyclohexene oxide (CHO) monomer and diphenyliodonium salt at λ = 350 nm produced graft copolymers. The polymers synthesized were characterized by means of FTIR, HNMR and gel permeation chromatography measurements. All the spectroscopic studies revealed that arnmacromonomer of polystyrene with cyclohexene oxide (CHO) functionality at the chain end(s) (PSt-CHO) and their brush-type and graft copolymers were obtained.