Synthesis of Hydroxyl-functionalized 3,4-Poly(2-aryl-1,3-butadiene)s

The polymerization of 2-(4-methylphenyl)-1,3-butadiene (2-MPBD) is performed using [C13H8CH2CH2(NCHCCHN)C6H2Me3-2,4,6]Lu(CH2SiMe3)(2) (1), Ph2P(=NDip)(NDip)Lu(CH2Si-Me-3)(2)(THF) (Dip=C6H3-2, 6-Pr-i(2); 2), Ph2P(=NDip) (NC6H3-2-Et)Lu(CH2SiMe3)(2)(THF) (3) and Ph2P(=NDip) (NC6H3-2-Et)Sc(CH2SiMe3)(2)(THF) (4). The microstructures and thermal properties of resultant polymers are characterized by nuclear magnetic resonance spectroscopy (H-1-NMR, C-13-NMR), gel permeation chromatography (GPC) and differential scanning calorimetry (DSC). Complex 1, activated by [Ph3C][B(C6F5)4] and (AlBu3)-Bu-i, shows low catalytic activity and 3,4-selectivity (65.2%) for 2-MPBD polymerization. Under the same conditions, complex 2 is nearly inert. In contrast, complexes 3 and 4 demonstrate high 3,4-selectivity (98.1% and >99%, respectively) and enable 100% conversion of 200 equivalents of 2-MPBD into polymers at 20. with 2 min. The resultant molecular weights increase with monomer-to-catalyst ratios varying from 200:1 to 600:1 with narrow molecular weight distributions of 1.12- 1.25. Furthermore, complex 4 also shows high catalytic activity and high 3,4-selectivity for the polymerizations of 2-phenyl-1,3-butadiene, 2-(3-methylphenyl)-1,3-butadiene, 2-(4-pentylphenyl)-1,3-butadiene, 2-(4-fluorophenyl)-1,3-butadiene and 2-(4-chlorophenyl)-1,3-butadiene. The resultant 3,4-poly(2-aryl-1,3-butadiene)s are readily transformed into hydroxyl functionalized polymers by the treatment of BH3 and H2O2.