Half Metallocene Catalyst for Syndiotactic Styrene Polymerization
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Solution Overview
Problem
Existing catalysts for synthesizing syndiotactic polystyrene require complex purification processes, exhibit low catalytic activity, and are costly due to the need for large amounts of alkylaluminum derivatives and expensive substituents, making them unsuitable for commercialization.
Innovation Solution
A new half metallocene catalyst system using transition metals from Groups 3 to 10, cycloalkanedienyl groups, and amine-based ligands with high steric hindrance, such as triethanolamine or N-alkyldiethanolamine, which allows for high stereoregularity and molecular weight control with a small amount of cocatalyst, enabling efficient styrene polymerization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional metallocene catalysts with cycloalkanedienyl groups are used for syndiotactic polystyrene synthesis, then polymerization can proceed, but catalytic activity is low requiring high mole ratios of styrene to catalyst (3,500:1 to 500,000:1)
Solution Approach 1:
The patent changes the chemical parameters of the catalyst by replacing conventional cycloalkanedienyl ligands with half-metallocene ligands containing oxygen donor atoms (such as β-diketonate or alkoxide ligands). This parameter change in ligand composition dramatically increases catalytic activity, allowing polymerization to proceed efficiently at much lower catalyst loadings.
2Productivity
If large amounts of alkylaluminum derivatives are used with conventional catalysts to achieve polymerization, then syndiotactic polystyrene can be synthesized, but complicated purification processes are required and production costs increase
Solution Approach 1:
The patent extracts and eliminates the need for large amounts of alkylaluminum cocatalysts by using the half-metallocene catalyst system that is inherently active with minimal or no aluminum cocatalyst. This removal of excessive cocatalyst requirement directly simplifies the purification process and reduces production costs.
Solution Approach 2:
The patent employs a catalyst system that requires minimal aluminum cocatalyst, effectively replacing the conventional approach that relies on large amounts of expensive aluminum derivatives. This substitution with a more efficient catalyst system reduces both material costs and process complexity.
3Manufacturing precision
If expensive substituent groups are introduced to cycloalkanedienyl groups to improve catalyst performance, then stereoregularity increases, but production cost increases making commercialization difficult
Solution Approach 1:
The patent changes the fundamental parameter of ligand structure from substituted cycloalkanedienyl groups to half-metallocene ligands with oxygen donors. This parameter change achieves high stereoregularity through the inherent electronic and steric properties of the half-metallocene structure without requiring expensive additional substituents.
Solution Approach 2:
The patent replaces expensive substituent groups on cycloalkanedienyl ligands with more economical half-metallocene ligands that achieve comparable or superior stereoregularity. This substitution with cheaper ligand systems maintains polymer quality while reducing production costs for commercialization.
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 catalyst system achieves high activity, stereoregularity, and broad molecular weight distribution, reducing production costs and simplifying the polymerization process while maintaining high polymer quality, making it suitable for commercial applications.
Implementation Method 1
a transition metal half metallocene catalyst with a noble structure for preparing syndiotactic styrene polymers having high activity
Data Source
AI summary
The present invention relates to a transition metal half metallocene catalyst with a noble structure for preparing syndiotatic styrene polymer having high activity, superior stereoregularity, high melting point and broad molecular weight distribution and a process for preparing styrene polymer using the same. The present invention provides a half metallocene catalyst having a single nucleus structure, in which a transition metal in Groups 3 to 10 on the periodic table is connected to a cycloalkanedienyl group or its derivative forming 5-coordinate bond on a side thereof and to any one of triethanolamine, N-alkyldiethanolamine and N-dialkylethanolamine group, all of which have a plurality of binding sites and high steric hinderance, on the other side thereof. The noble metallocene catalyst according to the present invention is useful for preparing highly syndiotatic vinyl aromatic polymer with broad molecular weight distribution and high activity.