Effective copolymerization of ethylene with α,ω-alkenols and homopolymerization of α,ω-alkenols catalyzed by aminophenolate zirconium complex

Abstract

A zirconium complex of diamine-bis(phenolate) ligand, [(tBu2O2NN’)ZrCl]2(μ-O) where (tBu2O2NN’) = Me2N(CH2)2N(CH2–2-O−-3,5-tBu2-C6H2)2, activated with (iBu)3Al/Ph3CB(C6F5)4, was for the first time used in copolymerization of ethylene with unsaturated alcohols (CH2 = CH(CH2)nCH2OH, where n = 7, 8, 3). The hydroxyl groups of comonomers were protected with R3-xAlClx (where x = 0 or 1, R = iBu, Et). In contrast to the formerly reported catalysts, the activity of this catalyst is much higher in ethylene/alkenols copolymerization than in ethylene homopolymerization and its lifetime is long. Moreover, the copolymers with high polar comonomer contents (up to 16.4 mol%, 52.3 wt%) were produced. The effects of copolymerization conditions such as comonomer/protecting agent molar ratio, comonomer concentration, ethylene pressure and reaction time on the catalyst activity and comonomer incorporation were studied. In addition, polyalkenols were synthesized by the coordination polymerization of α,ω-alkenols with the use of [(tBu2O2NN’)ZrCl]2(μ-O) and rac-Et(Ind)2ZrCl2 for reference. DSC, TG, GPC, SEM, 1H and 13C NMR, and FTIR methods were used to characterize the (co)polymerization products.