Functionalized syndiotactic polystyrene polymers prepared by the combination of metallocene catalyst and borane comonomer

This paper discusses an effective route in the functionalization of s-PS polymer that involves the direct copolymerization of styrene with a borane-containing styrenic monomer, i.e., 4-[B-(n-butylene)-9-BBN]styrene (B-styrene). The reactivity ratios of the two comonomers are quite close, with r(1) = 0.9 for styrene and r(2) = 1.2 for B-styrene in the Cp*Ti(OMe)(3)/MAO catalyst system. A broad composition range of syndiotactic poly(styrene-co-B-styrene) copolymers has been prepared with narrow molecular weight and composition distributions. The random copolymer structure was further evidenced by DSC and C-13 NMR analyses. With increasing B-styrene concentration, the copolymers show a systematic decrease in glass transition temperature, melting point, crystallization temperature, and crystallinity. At above 8.4 mol % B-styrene content, the crystallinity of the copolymer completely disappears. In turn, the borane groups in the copolymer are very versatile and can be quantitatively converted to other functional groups, such as hydroxy and anhydride groups, or transformed to free radical initiators for in situ free radical graft polymerization to prepare s-PS-g-PMMA graft copolymers.