A facile method for synthesis of ABA triblock copolymers with macro-iniferter technique

A facile method for synthesis of well-defined ABA triblock copolymers, such as poly(vinyl acetate-6-styrene-b-vinyl acetate), was investigated. The po lymerization proceeds 'living' radical mechanism realized by macro-iniferte r technique. The macro-iniferters were designed and synthesized by 'living' radical polymerization of vinyl monomers utilizing diethyl 2,3-dicyano-2,3 -di(p-N,N-diethyldithio-carbamymethyl)phenylsuccinate (DDDCS) as a multi-fu nctional iniferter, that is, under heating without ultra-violet (UV) light, DDDCS serve as a thermal iniferter by thc reversible cleavage of the hexa- substituted C-C bond, while under UV light irradiation at ambient temperatu re, it serve as a photoiniferter by the reversible cleavage of the two diet hyldithiocarbamyl (DC) functional groups. The polymers prepared via these t wo processes bearing alpha- and omega -DC end groups are macro-iniferters. The ABA triblock copolymers with different block components were easily syn thesized via 'living' polymerization through these macro-iniferters, The fo rmation of block copolymers were characterized by gel permeation chromatogr aph, H-1 nuclear magnetic resonance and differential scanning calorimeter a nalyses. (C) 2001 Elsevier Science Ltd. All rights reserved.