Synthesis and Characterization of a Novel Carbazole- containing Branched Random Copolymer Derived from α-Norbornene Methylene Polystyrene Macromonomer via Ring-opening Metathesis Polymerization

Abstract

A novel method for preparing α-norbornene methylene polystyrene macromonomer (NBMPSt) is reported. NBMPSt macromonomer ((average)Mn=1.60×10^5 and PDI=1.26) had glass transition temperature (T(subscript g)) of 107℃ for polystyrene segment. Since the homopolymerization of NBMPSt macromonomer with number average molecular weight ((average)Mn) 1.60×10^5 could not be carried out by ring-opening metathesis polymerization (ROMP) with Ru catalyst [(Cy3P)2Cl2Ru=CHPh, Cy=cyclohexyl], ring-opening metathesis copolymerization of NBMPSt macromonomer containing norbornene end group and norbornene monomer containing carbazole group (NBCbz) was investigated. A branched random copolymer containing carbazole groups and polystyrene segments, poly (NBMPSt-co-NBCbz), was successfully obtained ((average)Mn=3.99×10^5 and PDI=1.30). The molecular weight distributions of NBMPSt macromonomer and branched random poly(NBMPSt-co-NBCbz) are narrow. Branched random poly(NBMPSt-co-NBCbz) exhibited good solubility in a variety of solvents such as methylene chloride, chloroform, tetrahydrofuran, 1,2-dichlorobenzene, and even in xylene and benzene at room temperature or upon heating to 60℃.