Thiourea Group IV Metal Catalysts for Olefin Copolymerization
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Solution Overview
Problem
There is a need for improved polymerization catalysts to meet the industrial demand for olefin-based polymers, such as polyethylene, as existing catalyst systems do not fully satisfy the requirements for various applications.
Innovation Solution
The development of thiourea complexes, specifically those with Formula (I), which include metal centers like Ti, Zr, or Hf, and bidentate thiourea ligands, are used to catalyze the copolymerization of ethylene and α-olefins, providing alternative synthetic schemes for producing ethylene-co-alkylene copolymers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If existing catalyst systems are used for polyolefin polymerization, then basic polymer production is achieved, but the ability to meet diverse industrial demands for specific polymer properties is insufficient
Solution Approach 1:
The patent applies parameter changes by systematically varying the ligand structure (different R1, R2, R3 substituents on the thiourea ligand), metal center (Ti, Zr, Hf), and oxidation state to create a series of catalysts with tailored properties. This allows optimization of polymerization activity, copolymer composition, and polymer microstructure for different industrial applications.
Solution Approach 2:
The patent employs composite catalyst systems combining group 4 metal thiourea complexes with organometallic co-catalysts (such as methylaluminoxane or borate co-catalysts). This composite approach enhances catalytic activity and enables precise control over polymer properties that cannot be achieved with single-component catalysts.
2Productivity
If polymerization catalysts are designed for high activity, then productivity increases, but control over molecular weight distribution and branching becomes more difficult
Solution Approach 1:
The patent applies local quality by designing ligands with specific functional groups at different positions (R1, R2, R3 substituents) that independently influence different aspects of polymerization. For example, electron-donating groups may enhance activity while steric bulk at specific positions controls molecular weight, allowing simultaneous optimization of multiple parameters.
Solution Approach 2:
The patent utilizes dynamic ligand design where the thiourea ligand can adopt different coordination modes or conformations during the polymerization cycle. This dynamic behavior allows the catalyst to adapt its structure to balance high activity with precise control over polymer microstructure and molecular weight distribution.
3Ease of manufacture
If simple catalyst systems are used, then ease of manufacture is improved, but the ability to produce copolymers with desired properties is limited
Solution Approach 1:
The patent applies segmentation by dividing the catalyst system into modular components: the thiourea ligand framework, the group 4 metal center, and optional co-catalysts. This modular structure allows independent optimization of each component and simplifies synthesis while maintaining the ability to produce copolymers with precise composition and microstructure 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
These thiourea complexes enable the production of ethylene-co-alkylene copolymers with desired properties, including controlled molecular weight distribution and branching, enhancing the properties and applications of the resulting polymers.
Implementation Method 1
thiourea complexes enable the production of ethylene-co-alkylene copolymers
Data Source
AI summary
Catalyst compositions and polymerization systems include at least one thiourea complex according to Formula (I): MQaX4-a (I) in which M is Ti, Zr, or Hf; a is 1 or 2; each group Q of the thiourea complex is a bidentate thiourea ligand bound to the metal center and having Formula (Ia), Formula (Ib), or Formula (Ic): (Formulas should be inserted here). In Formulas (Ia), (Ib), and (Ic), each group R1, R2, and R3 is independently chosen from alkyl groups or aryl groups; each group Z1 or Z2 is independently chosen from alkylene groups. If a=2, groups R1 of the two groups Q are optionally linked, or groups R3 of the two groups Q are optionally linked. Each X is covalently bonded or coordinated to the metal center and is independently chosen from alkyl groups or halides. The polymerization systems may be configured to copolymerize ethylene and α-olefins.