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Ethylene Polymerizations Using Parallel Pressure Reactors and a Kinetic Analysis of Chain Transfer Polymerization
Published on: November 27, 2015
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Tri- and tetra-dentate imine vanadyl complexes: synthesis, structure and ethylene polymerization/ring opening
Jing Ma1, Ke-Qing Zhao, Mark Walton
1College of Chemistry and Materials Science, Sichuan Normal University, Chengdu, 610066, China.
Dalton Transactions (Cambridge, England : 2003)
|October 2, 2014
Summary
New vanadium complexes act as highly active catalysts for ethylene polymerization, producing linear polyethylene and ultra-high molecular weight polyethylene. These catalysts also show potential for ring-opening polymerization of caprolactone under specific conditions.
Area of Science:
- Coordination Chemistry
- Polymer Chemistry
- Organometallic Chemistry
Background:
- Vanadium complexes are versatile catalysts in olefin polymerization.
- Developing efficient catalysts for producing polyethylene with controlled molecular weights is crucial.
- Exploring new ligand designs can modulate catalytic activity and selectivity.
Purpose of the Study:
- To synthesize and characterize novel vanadium complexes with tailored ligand environments.
- To evaluate the catalytic performance of these complexes in ethylene polymerization.
- To investigate their activity in the ring-opening polymerization of ε-caprolactone.
Main Methods:
- Synthesis of vanadium complexes using Schiff base ligands and vanadium precursors.
- Structural characterization of the complexes using X-ray crystallography.
- Catalytic screening in ethylene polymerization using various co-catalysts (DEAC, DMAC, MAO) and additives (ETA).
- Evaluation in ring-opening polymerization of ε-caprolactone.
Main Results:
- Complexes [VOCl2L(1)] and [L(2-4)VO] were synthesized and structurally characterized.
- Ethylene polymerization using DEAC/ETA yielded linear polyethylene with high activities (3000-10,700 g (mol h bar)(-1)).
- Complex 3 with DMAC/ETA demonstrated exceptional activity (63,000 g (mol h bar)(-1)) producing ultra-high molecular weight polyethylene (UHMWPE).
- Propylene incorporation in ethylene-propylene copolymerization ranged from 6.9-8.8 mol% with complex 3.
- Ring-opening polymerization of ε-caprolactone showed moderate conversions (~80%) at 110 °C.
Conclusions:
- The synthesized vanadium complexes are effective pre-catalysts for ethylene polymerization, yielding polymers with varying molecular weights.
- The choice of co-catalyst significantly impacts catalytic activity and polymer properties, with DMAC being particularly effective.
- Complex 3 shows promise for producing UHMWPE and functional copolymers.
- Catalytic activity in ring-opening polymerization of ε-caprolactone is observed at elevated temperatures.
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