A post-metallocene titanium(IV) complex bearing asymmetric tetradentate [ONNO]-type amino acid-based ligand and its activity toward polymerization of polar monomers at room temperature in aqueous emulsion

Abstract

Due to increasing environmental concern regarding detrimental effects of organic solvents, a new post-metallocene titanium-based catalyst [TiLCl2] {LH2=2-(3,5-Di-tert-butyl-2-hydroxy-benzylamino)-succinamic acid} with sidearm approach has been synthesized for aqueous emulsion polymerization of olefins. The catalyst has been characterized by elemental analysis, 1H NMR, 13C NMR, HRMS, IR, and UV–visible spectroscopy. The catalyst is easy to synthesize and is moderately stable in water. In aqueous emulsion, in the presence of co-catalyst NaBPh4, it has been found to exhibit moderate to high activity in the range of 104 to produce homopolymers and copolymers of methyl acrylate and methyl methacrylate which are widely used for a variety of applications. The influence of the main reaction parameters on the polymerization reactions at room temperature was studied including the catalyst/co-catalyst ratio, type of monomers, reaction time, etc. Structures and properties of the obtained polymers were analyzed by various instrumental techniques like differential scanning calorimetry (DSC), gel permeation chromatography (GPC), 1H NMR, 13C NMR, etc., as well as by various experimental methods. The results indicated that the PMMA and PMA produced by the newly synthesized catalytic system are syndiotactic rich and possess ultrahigh-viscosity average molecular weight in the order of 106 g/mol.