Synthesis and characterization of isotactic poly(p-hydroxystyrene)- block-1,4-trans-polybutadiene by sequential monomer addition using titanium complex with an [OSSO]-type Bis(phenolate) ligand

Herein, we demonstrated the synthesis and characterization of a well-defined diblock copolymer consisting of isotactic poly(p-hydroxystyrene) (iP(p-HOS)) and 1,4-trans-polybutadiene (1,4-trans-PBD), iP(p-HOS)-b-1, 4-trans-PBD, by the combination of sequential monomer addition and deprotection. Isospecific living polymerization of p-tert- butyldimethylsilyloxystyrene and living trans-1,4-polymerization of 1,3-butadiene were catalyzed by 1, 4-dithiabutandiyl-2, 2ʹ-bis(6-cumenyl-4-methylphenoxy) titanium dichloride (complex 1) activated by methylaluminoxane (MAO) at room temperature to provide highly stereospecific isotactic poly(p-tert-butyldimethylsilyloxystyrene) (iP(p-TBDMSOS)) and 1,4-trans-polybutadiene (1,4-trans-PBD) with narrow molecular weight distribution. Furthermore, the iP(p-TBDMSOS)-b-1, 4-trans-PBD was prepared via sequential monomer addition in the presence of complex 1 and MAO. The deprotection of the iP(p-TBDMSOS) block was promoted by concentrated hydrochloric acid to produce iP(p-HOS)-b-1, 4-trans-PBD. In addition, the resultant diblock copolymer and intermediate polymers were characterized by gel permeation chromatography, nuclear magnetic resonance and differential scanning calorimeter.