Synthesis and catalytic performance of a new post-metallocene titanium complex having asymmetric tetradentate [ONSO]-type amino acid-based chelating ligand for acrylate polymerization at room temperature in aqueous emulsion

• Published in: Colloid and polymer science 2018, Vol.296 (1), p.107-119
• Main Authors: De, Sudip K., Sharma, K., Sharma, C.
• Format: Article
• Language: English
• Subjects: Alkenes; Ambient temperature; Butyric acid; Catalysis; Catalysts; Catalytic activity; Characterization and Evaluation of Materials; Chelation; Chemical synthesis; Chemistry; Chemistry and Materials Science; Complex Fluids and Microfluidics; Copolymerization; Emulsion polymerization; Food Science; Infrared radiation; Ligands; Liquid chromatography; Low molecular weights; Molecular structure; Molecular weight distribution; Nanotechnology and Microengineering; NMR; Nuclear magnetic resonance; Original Contribution; Physical Chemistry; Polymer Sciences; Polymerization; Polymethyl methacrylate; Room temperature; Soft and Granular Matter; Syndiotacticity; Titanium
• ISSN: 0303-402X; 1435-1536
• DOI: 10.1007/s00396-017-4234-2

A new titanium(IV) complex [TiLCl 2 ] {LH 2  = 2-(3,5-di- tert -butyl-2-hydroxy-benzylamino)-4-methysulfanyl-butyric acid} having S-, N-, and O-bearing phenoxy-amine backbones has been synthesized and investigated for its efficient role in aqueous emulsion polymerization of polar olefins, methylacrylate and methylmethacrylate at ambient temperature. The catalyst microstructure has been supported by elemental analysis, 1 H and 13 C NMR, IR, and UV–visible spectroscopy. The catalyst is easy to synthesize and found to be moderately stable in water. Upon activation with BPh 4 − , the activity of the complex as single-site catalytic species has been found to be high (in the order of 10 4  g mol −1  h −1 ) producing syndiotactic rich high molecular weight polymers with low molecular weight distribution (PDI values in the range of 1.2–1.4). Structure and molecular properties of the synthesized polymers were determined by 1 H NMR, 13 C NMR, gel permeation chromatography, and DSC analysis. DSC analysis reveals that the polymer product obtained is semi-crystalline with sharp melting temperature at 286.9 °C ( T m ). Kinetic parameters such as rate constant and activation energy of polymethylmethacrylate have also been studied, and the value of E app has been found to be 58.842 kJ mol −1 only. The lower value can be interpreted as a consequence of a high catalytic activity of the complex. Graphical abstract A new [ONSO]-type mono(phenolato) titanium(IV) complex [TiLCl 2 ] {LH 2  = 2-(3,5-di- tert -butyl-2-hydroxy-benzylamino)-4-methysulfanyl-butyric acid} with soft pendant donor has been synthesized for aqueous emulsion polymerization of polar olefins. Interestingly, it was reported in the literature that the side arm approach is the efficient strategy to design highly active metal catalysts. Therefore, in this paper, we have studied the influence of ligand with hard (N, O) and soft (S) pendant donors on the efficacy of present catalyst in achieving syndioselective homo and copolymerization of polar olefins (methyl acrylate and methyl methacrylate) under normal reaction conditions.