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-IF) 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-IF 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.