Bimetallic Catalyst Suppresses Long-Chain Branching in VNB Polymerization
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Solution Overview
Problem
The production of polymers containing 5-vinyl-2-norbornene (VNB) using existing processes results in high long-chain branching, leading to gelation and broadening of molecular weight distribution, which negatively impacts the mechanical properties and stability of the polymerization process, making it unsuitable for certain rubber applications.
Innovation Solution
A bimetallic complex with a cyclopentadienyl and amidine ligand is developed, which incorporates non-conjugated dienes like VNB, exhibiting decreased long-chain branching properties compared to monometallic catalysts, thereby stabilizing the polymerization process and improving mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If monometallic catalyst components are used for polymerization of VNB, then polymerization activity is achieved, but long-chain branching increases leading to gelation and broad molecular weight distribution
Solution Approach 1:
The patent combines two metal centers (typically Group 4 and Group 6 metals) into a bimetallic catalyst complex, where the synergistic interaction between the two metal centers enables effective polymerization of VNB while suppressing long-chain branching and gelation, thus resolving the contradiction between achieving polymerization activity and maintaining narrow molecular weight distribution
Solution Approach 2:
The catalyst system employs a composite structure with two different metal centers coordinated to specific ligands (such as cyclopentadienyl and amidine ligands), creating a bimetallic complex that exhibits enhanced selectivity and control over polymerization, preventing excessive branching while maintaining productivity
2Quantity of substance
If conventional catalyst systems are used for VNB polymerization, then polymer production is achieved, but gelation occurs making the polymer unsuitable for shaped articles
Solution Approach 1:
By merging two metal centers into a bimetallic complex, the catalyst achieves a balance between productivity and polymer stability, producing polymer with controlled architecture that prevents gelation while maintaining high production rates, making the polymer suitable for applications requiring shaped articles
3Productivity
If bimetallic catalysts with cooperative effects are used, then polymerization efficiency is enhanced, but long-chain branching increases which is disadvantageous for rubber properties
Solution Approach 1:
The bimetallic catalyst exhibits local quality differentiation where each metal center performs a specific function: one metal center primarily facilitates monomer insertion while the other controls chain transfer and branching reactions, creating a division of labor that enhances efficiency while suppressing harmful long-chain branching
Solution Approach 2:
The patent optimizes parameters including the choice of metals (Group 4 and Group 6), ligand structure (cyclopentadienyl and amidine), and their stoichiometric ratios to achieve the desired balance between polymerization efficiency and suppression of long-chain branching, transforming the catalyst's chemical and structural parameters to eliminate harmful effects
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
The bimetallic complex reduces long-chain branching, enhancing the mechanical properties of the polymer and stabilizing the polymerization process, making the polymer suitable for rubber compositions in automotive and braking system applications.
Implementation Method 1
a bimetallic complex of the formula (1)... a process for the polymerization of at least one olefin... in the presence of a polymerization catalyst component
Implementation Method 2
The propensity of such bimetallic catalysts to display so-called cooperative effects which can influence polymer properties such as long chain branching
Data Source
AI summary
The present invention relates to a new bimetallic complex of the formula (1) wherein: M is a group 4-6 metal R1 means is a substituent comprising a heteroatom of group 15, through which R1 is bonded to the imine carbon atom; R2-R6 are the same or different and each represents a hydrogen atom, an optionally substituted C1-10 alkyl group, an optionally substituted C1-10 alkoxy group, an optionally substituted C6-20 aryl group, an optionally substituted C6-20 aryloxy group, an optionally substituted C7-20 aralkyl group, an optionally substituted C7-20 aralkyloxy group, a silyl group substituted with optionally substituted C1-20 hydrocarbon group(s), a C1-20 hydrocarbon-substituted amino group or the adjacent R2-R6 may be linked to each other to form a ring; R7-R10 are the same or different and each represents a hydrogen atom, a halogen atom, an optionally substituted C1-10 alkyl group, an optionally substituted C1-10 alkoxy group, an optionally substituted C6-20 aryl group, an optionally substituted C6-20 aryloxy group, an optionally substituted C7-20 aralkyl group, an optionally substituted C7-20 aralkyloxy group, a silyl group substituted with optionally substituted C1-20 hydrocarbon group(s), a C1-20 hydrocarbon-substituted amino group or the adjacent R7-R10 may be linked to each other to form a ring; L is an optional neutral Lewis basic ligand, and j is an integer denoting the number of neutral ligands L; and X is an anionic ligand, and r is an integer denoting the number of anionic ligands X and wherein the two cyclopentadienyl-amidinato-metal-containing moieties as in the brackets are the same or different.