Synthesis and characterization of poly(styrene-co-4-[(tert-butyldimethylsilyl)oxy]styrene) as a precursor of hydroxyl-functionalized syndiotactic polystyrene

The ligand effects of homogeneous Ti-based catalysts for the copolymerizati on of styrene ([M-1]) with 4-[(tert-butyldimethylsilyl)oxy] styrene (TBDMSS ; [M-2]) were investigated by the UV/visible spectroscopic analysis. Concer ning the higher yields from the copolymerization of styrene with TBDMSS, th e half-sandwich type of titanocene having pi-ligands compared to titanium ( TV) butoxide (Ti(OBu)(4)) having a-ligands was a more effective catalysts. The silyloxy group exhibiting a negative a value in the Hammett sigma-rho r elationship reduced the activities of titanocenes. The stronger electron-do nating substituent on the iz-ligand leading to the increase in the catalyti c activity in syndiospecific polymerization of styrene contributed to the d ecrease of the reactivity of the "cationlike" metal center due to both elec tronic and steric effects. The reactivity ratios, r(1) and r(2), in the eta (5)-indenyl trichlorotitanium ((Ind)TiCl3)-catalyzed copolymerization of st yrene with TBDMSS in the presence of methylaluminoxane (MAO) ([Al]/[Ti] = 2 000) were 0.997 and 7.27 from the evaluation of Finmann and Ross, respectiv ely. The r(1)r(2) product value (7.25) indicates that a block type of copol ymer may be produced in a relatively high feed range of TBDMSS to styrene.