Syntheses of polyolefin-based stereoregular diblock copolymers for self-assembled nanostructures

The preparation of polyolefin-based stereoregular diblock copolymers by postpolymerization of ethenyl-capped syndiotactic polypropylene-based propylene/norbornene copolymer (sPP-based P-N copolymer) led to the successful generation of a structurally uniform stereoregular diblock copolymer for self-assembly studies. The ethenyl-capped prepolymer was prepared by conducting propylene/norbornene copolymerization in the presence of Me2C(Cp)(Flu)ZrCl2/MAO. Ozonolysis of ethenyl-capped sPP-based P-N copolymer provided the formyl group end-capped, end-functionalized prepolymer with a quantitative functional group conversion ratio. Subsequently, connecting the formyl end-group of the stereoregular prepolymer by coupling with living anionic polystyrene resulted in the high yield production of stereoregular diblock copolymer (sPP-based P-N-block-polystyrene), which is difficult to prepare by other methods. The resulting stereoregular diblock copolymer possesses precise chemical architecture to self-organize into consistent nanostructures as evidenced by transmission electron microscopy and small angle X-ray scattering. (C) 2008 Wiley Periodicals, Inc.