Synthesis and Characterization of Poly(styrene-co-4-[(tert-butyldimethylsilyl)oxy]styrene) as a Precursor of Hydroxyl-Functionalized Syndiotactic Polystyrene

Abstract

The ligand effects of homogeneous Ti-based catalysts for the copolymerization of styrene ([M1]) with 4-[(tert-butyldimethylsilyl)oxy]styrene (TBDMSS; [M2]) were investigated by the UV/visible spectroscopic analysis. Concerning the higher yields from the copolymerization of styrene with TBDMSS, the half-sandwich type of titanocene having π-ligands compared to titanium (IV) butoxide (Ti(OBu)4) having σ-ligands was a more effective catalysts. The silyloxy group exhibiting a negative σ value in the Hammett σ−ρ relationship reduced the activities of titanocenes. The stronger electron-donating substituent on the π-ligand leading to the increase in the catalytic activity in syndiospecific polymerization of styrene contributed to the decrease of the reactivity of the “cationlike” metal center due to both electronic and steric effects. The reactivity ratios, r1 and r2, in the η5-indenyl trichlorotitanium ((Ind)TiCl3)-catalyzed copolymerization of styrene with TBDMSS in the presence of methylaluminoxane (MAO) ([Al]...