Salan Catalyst Vinyl-Terminated Polyethylene Long Chain Branching
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Solution Overview
Problem
There is a need for new and improved catalyst systems for olefin polymerization to achieve specific polymer properties such as high melting point, high molecular weight, long chain branching, vinyl termination, increased conversion, and altered comonomer distribution without compromising polymer quality.
Innovation Solution
The use of catalyst compounds comprising Group 3, 4, 5, or 6 transition metals with tetradentate di-anionic Salan ligands, in combination with activators, to polymerize olefins and produce polyolefins with at least 50% allylic vinyl end groups and number average molecular weight (Mn) of at least 200 g/mol, as determined by 1H NMR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional olefin polymerization catalysts are used, then polymer production is achieved, but the polymer properties cannot be optimized for high melting point, high molecular weight, long chain branching, and vinyl termination simultaneously
Solution Approach 1:
The patent applies parameter changes by modifying the catalyst structure - specifically using Group 4 transition metals (Zr, Hf, Ti) coordinated with tetradentate ligands (N^N^O^O type) and varying the activator (MAO, B(C6F5)3, AlCl3) to achieve precise control over polymer properties including molecular weight, melting point, and chain branching while maintaining high vinyl termination
Solution Approach 2:
The patent employs composite catalyst systems combining multiple components - the transition metal complex, the tetradentate ligand framework, and the activator - to create a synergistic system that enables simultaneous optimization of multiple polymer properties that cannot be achieved with single-component catalysts
2Strength
If high molecular weight polyolefins are produced, then polymer strength increases, but achieving high vinyl termination and long chain branching becomes difficult
Solution Approach 1:
The patent applies local quality by creating specific local structures in the polymer - high vinyl termination at chain ends (allylic vinyl end groups) and long chain branching at specific positions along the backbone - while maintaining high overall molecular weight, achieving different structural qualities at different locations in the polymer
3Productivity
If catalyst systems are optimized for high conversion, then productivity increases, but comonomer distribution and polymer quality deteriorate
Solution Approach 1:
The patent applies dynamics by enabling the catalyst to dynamically adjust its behavior - the Group 4 metal complex with tetradentate ligand maintains high activity for monomer insertion (high conversion) while also facilitating controlled comonomer incorporation and chain transfer reactions, achieving high productivity without sacrificing comonomer distribution control
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables the production of polyolefins with enhanced properties, including high molecular weight and long chain branching, while maintaining high vinyl termination and comonomer incorporation efficiency.
Implementation Method 1
contacting one or more olefins with a catalyst system at a temperature, a pressure, and for a period of time sufficient to produce a polyolefin
Data Source
AI summary
Vinyl terminated polyolefins with long chain branching produced with Salan catalysts having carbazole moieties