Here, we described a strategy for preparing well-defined block copolymers, poly(styrene)-b-poly(vinyl acetate) (PS-b-PVAc), containing middle azobenzene moiety via the combination of the reversible addition-fragmentation chain transfer (RAFT) polymerization and "click" chemistry. Firstly, a novel RAFT agent containing alpha-alkyne and azobenzene chromophore in R group, 2-(3-ethynylphenylazophenoxy carbonyl)prop-2-yl-9H-carbazole-9-carbodithioate (EACDT), was synthesized and used to mediate the RAFT polymerization of styrene (St). Well-defined a-alkyne end-functionalized poly(styrene) (PS) was obtained. Secondly, the RAFT polymerization of vinyl acetate (VAc) was conducted using functionalized RAFT reagent with omega-azide structure in Z group, O-(2-azidoethyl) S-benzyl dithiocarbonate (AEBDC). Well-defined omega-azide end-functionalized poly(vinyl acetate) (PVAc) was obtained. Afterwards, the resulting alpha-alkyne terminated PS was coupled by "click" chemistry with the azide terminated PVAc. The block copolymer, PS-b-PVAc, was obtained with tailored structures. The products from each step were characterized and confirmed by GPC, H-1 NMR, IR and differential scanning calorimetry (DSC) examination. Kinetics of the trans-cis-trans isomerization from azobenzene chromophore in PS-b-PVAc and PS were investigated in CHCl3 solutions. (C) 2010 Elsevier Ltd. All rights reserved.