Polypropylene and poly(ethylene-co -1-octene) effective synthesis with diamine-bis(phenolate) complexes: Effect of complex structure on catalyst activity and product microstructure

Abstract

A series of group 4 metal complexes bearing amine-bis(phenolate) ligands with the amino side-arm donor: (μ-O)[Me2N(CH2)2N(CH2-2-O-3,5-tBu2-C6H2)2ZrCl]2 (1a), R2N(CH2)2N(CH2-2-O-3-R1-5-R2-C6H2)2TiCl2 (R = Me, R1, R2 = tBu (2a), R = iPr, R1, R2 = tBu (2b), R = iPr, R1 = tBu, R2 = OMe (2c)), and Me2N(CH2)2N(CH2-2-O-3,5-tBu2-C6H2)(CH2-2-O-C6H4)TiCl2 (2d) are used in ethylene and propylene homopolymerization, and ethylene/1-octene copolymerization. All complexes, upon their activation with Al(iBu)3/Ph3CB(C6F5)4, exhibit reasonable catalytic activity for ethylene homo- and copolymerization giving linear polyethylene with high to ultra-high molecular weight (600·× 103–3600·× 103 g/mol). The activity of 1a/Al(iBu)3/Ph3CB(C6F5)4 shows a positive comonomer effect, leading to over 400% increase of the polymer yield, while the addition of 1-octene causes a slight reduction of the activity of the complexes 2a-2d. The complexes with the NMe2 donor group (2a, 2d, 1a) display a high ability to incorporate a comonomer (up to 9–22 mol%), and the use of a bulkier donor group, N(iPr)2 (2b, 2c), results in a lower 1-octene incorporation. All the produced copolymers reveal a broad chemical composition distribution. In addition, the investigated complexes polymerized propylene with the moderate (1a, 2a) to low (2b-2d) activity, giving polymers with different microstructures, from purely atactic to isotactically enriched (mmmm = 28%). © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017