Block Copolymer Preparation Using Sequential Normal/Living Radical Polymerization Techniques

Anionic and nitroxide-mediated (NM) radical polymerization works well for styrene but not for acrylates. We have overcome this problem and successfully prepared styrene- b - n -butyl acrylate (S-BA), styrene- b -methyl methacrylate (S-MMA), styrene- b -isoprene (S-IP), and styrene- alt -acrylonitrile- b -isoprene (SAN-IP) polymers using a sequential normal/living radical polymerization scheme. Clear (S-IP and SAN-IP) to translucent (S-BA and S-MMA) films were obtained having microphase-separated polymer morphology. GPC studies and chemical digestion of the IP segments of S-IP and SAN-IP block copolymers confirmed their block structure. The sequential normal/living radical polymerization approach provides a new route to synthesize block polymers that have previously proven very difficult to make.