Synthesis and characterization of graft copolymers of syndiotactic polystyrene with polybutadiene and 4-methylstyrene

Authors

  • Nathinee Srinate,

    1. Center of Excellence in Catalysis and Catalytic Reaction Engineering, Department of Chemical Engineering, Faculty of Engineering, Chulalongkorn University, Bangkok, Thailand 10330
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  • Supakanok Thongyai,

    Corresponding author
    1. Center of Excellence in Catalysis and Catalytic Reaction Engineering, Department of Chemical Engineering, Faculty of Engineering, Chulalongkorn University, Bangkok, Thailand 10330
    • Center of Excellence in Catalysis and Catalytic Reaction Engineering, Department of Chemical Engineering, Faculty of Engineering, Chulalongkorn University, Bangkok, Thailand 10330
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  • Piyasan Praserthdam

    1. Center of Excellence in Catalysis and Catalytic Reaction Engineering, Department of Chemical Engineering, Faculty of Engineering, Chulalongkorn University, Bangkok, Thailand 10330
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Abstract

The basic method for synthesizing syndiotactic polystyrene-g-polybutadiene graft copolymers was investigated. First, the syndiotactic polystyrene copolymer, poly(styrene-co-4-methylstyrene), was prepared by the copolymerization of styrene and 4-methylstyrene monomer with a trichloro(pentamethyl cyclopentadienyl) titanium(IV)/modified methylaluminoxane system as a metallocene catalyst at 50°C. Then, the polymerization proceeded in an argon atmosphere at the ambient pressure, and after purification by extraction, the copolymer structure was confirmed with 1H-NMR. Lastly, the copolymer was grafted with polybutadiene (a ready-made commercialized unsaturated elastomer) by anionic grafting reactions with a metallation reagent. In this step, poly(styrene-co-4-methylstyrene) was deprotonated at the methyl group of 4-methylstyrene by butyl lithium and further reacted with polybutadiene to graft polybutadiene onto the deprotonated methyl of the poly(styrene-co-4-methylstyrene) backbone. After purification of the graft copolymer by Soxhlet extraction, the grafting reaction copolymer structure was confirmed with 1H-NMR. These graft copolymers showed high melting temperatures (240–250°C) and were different from normal anionic styrene–butadiene copolymers because of the presence of crystalline syndiotactic polystyrene segments. Usually, highly syndiotactic polystyrene has a glass-transition temperature of 100°C and behaves like a glassy polymer (possessing brittle mechanical properties) at room temperature. Thus, the graft copolymer can be used as a compatibilizer in syndiotactic polystyrene blends to modify the mechanical properties to compensate for the glassy properties of pure syndiotactic polystyrene at room temperature. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

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