Synthesis and Characterization of Acrylonitrile-Styrene Block Copolymer Prepared by RAFT Technique

Carboxylterminated polyacrylonitrile and polystyrene as macroRAFT agents were synthesized by reversible additionfragmentation chain transfer(RAFT) polymerization using S，S′-bis(α，α′-dimethyl-α″-acetic acid)trithiocarbonate as the chain transfer agent. Poly(acrylonitrile)-b-poly(styrene)-b-poly(acrylonitrile)(PAN-b-PS-b-PAN) and poly(styren)-b-poly(acrylonitrile)-b-poly(styrene) (PS-b-PAN-b-PS) triblock copolymers were synthesized using acrylonitrile and styrene as monomers and macroRAFT agent as the chain transfer agents，respectively. The molecular structure and molecular weight of the products were characterized using 1HNMR，FTIR spectra and gel permeation chromatography(GPC). Atomic force microscope(AFM) and Raman spectra were used to study the microphase separation structure and pyrolysis behavior of the block copolymer films. Results showed that the molecular weight distribution(PDI) of the resulting products，except PAN-b-PS-b-PAN，was less than 1.2. After stabilization at 250 ℃ and pyrolysis at 600 ℃，thin films of block copolymer carbonized to uniform graphite structure about 75 nm in size.