Synthesis of New Dendritic Titanium Catalysts and Catalytic Ethylene Polymerization

Abstract

The 1.0G dendrimer polyamidoamine (PAMAM), 3,5-dichlorosalicylaldehyde, and TiCl4·2THF were used as synthetic materials, and the dendritic salicylaldehyde imide ligand with substituent hindrance and its titanium catalyst were synthesized by the condensation reaction of Schiff base. The structure of the synthesized products was characterized by infrared spectroscopy, nuclear magnetic resonance hydrogen spectroscopy, ultraviolet spectroscopy, electrospray mass spectrometry, and inductively coupled plasma-mass spectrometry. Activated methylaluminoxane (MAO) was used as a catalyst precursor for ethylene polymerization in the process of ethylene catalytic. The effects of ethylene polymerization were studied in terms of the Al/Ti molar ratio, reaction time, reaction temperature, polymerization pressure, and ligand structure of the catalyst. The results show good catalytic performance (70.48 kg PE/mol Ti·h) for ethylene polymerization because of the existence of ortho substituent hindrance on the salicylaldehyde skeleton. Furthermore, high-temperature gel permeation chromatography (GPC)-IR, differential scanning calorimetry (DSC), and torque rheometer were used to characterize the microstructure, thermal properties, and viscoelastic state of the polyethylene samples obtained. The results showed that the product was ultrahigh-molecular-weight polyethylene.

Syntheses and Catalytic Behavior of Dendritic Macrocyclic Schiff‐Base Nickel (II) Complexes in Ethylene Oligomerization

“…Benito and co‐workers proved that the catalytic activity of dendritic nickel (II) catalyst was higher than the mononuclear nickel catalyst in ethylene oligomerization and polymerization [1] . Series of the dendrimer bridged transition metal complexes were synthesized with dendrimers as materials for ethylene oligomerization in previous works, and these complexes had high activity in ethylene oligomerization [2] . Many works devoted to studying the effects of the substituent structure and the ligand backbone on their catalytic properties of dendrimer bridged metal complexes in oligo/polymerization [3] .…”

“…[1] Series of the dendrimer bridged transition metal complexes were synthesized with dendrimers as materials for ethylene oligomerization in previous works, and these complexes had high activity in ethylene oligomerization. [2] Many works devoted to studying the effects of the substituent structure and the ligand backbone on their catalytic properties of dendrimer bridged metal complexes in oligo/polymerization. [3] However, there are few reports about nickel complexes based on dendritic macrocyclic ligands for ethylene oligomerization.…”

Electrocatalytic Activity of PMMA–Anatase TiO2 Nanocomposites

“…(1) Interestingly, Titanium dioxide featuring catalytic activity in a number of chemicals, electrochemical and photochemical redox processes attracted our attention which eventually led to the development of metal oxide component with conducting polymer-based nanocomposites. (2,3) Even low concentrations of TiO2 NPs can induce new physiochemical, optical, and electrical properties, resulting in a favorable new class of nanocomposite materials (4)(5)(6)(7)(8). To the best of our knowledge, many studies have investigated the effects of adding TiO2 NPs on the physical, mechanical, thermal stability and biological behavior of a PMMA matrix.…”