Transition Metal Catalyst Ligand Design for Olefin Polymerization
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Solution Overview
Problem
Current catalysts for olefin polymerization lack enhanced polymerization efficiency and structural stability, limiting their effectiveness in producing low-density olefin-based polymers, particularly at high temperatures and with monomers having large steric hindrance.
Innovation Solution
A transition metal compound with a dibenzothiophene-fused cyclopentadienyl ligand and an amino group linked to a phenylene bridge, forming a rigid pentagonal ring structure, which facilitates excellent polymerization reactivity and structural stability, enabling the production of low-density olefin-based polymers with improved copolymerization of ethylene and alpha-olefins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional metallocene catalysts are used, then polymerization activity is maintained, but polymerization efficiency decreases at high temperatures and with monomers having large steric hindrance
Solution Approach 1:
The patent modifies the ligand structure parameters by introducing a dibenzothiophene-fused cyclopentadienyl framework with an amino group linked to a phenylene bridge. This structural parameter change creates a rigid pentagonal ring that maintains catalyst performance across varying temperatures and monomer types, resolving the contradiction between productivity and reliability.
Solution Approach 2:
The patent creates a composite catalyst system combining the transition metal center with the complex dibenzothiophene-fused cyclopentadienyl ligand system. This composite structure integrates multiple functional elements (the fused ring system for rigidity, the amino group for coordination, the phenylene bridge for connectivity) that work together to maintain both high productivity and reliability under diverse polymerization conditions.
2Productivity
If catalysts with enhanced polymerization efficiency are developed, then copolymerization performance improves, but structural stability decreases
Solution Approach 1:
The patent segments the ligand structure into distinct functional modules: the dibenzothiophene-fused cyclopentadienyl unit provides structural stability through its rigid pentagonal ring, while the amino group linked via phenylene bridge enables enhanced copolymerization performance. This segmentation allows each module to independently contribute its specific function without compromising the other.
Solution Approach 2:
The patent introduces a three-dimensional rigid pentagonal ring structure formed by the dibenzothiophene-fused cyclopentadienyl framework. This dimensional change from planar to立体结构 provides structural stability while the extended architecture through the phenylene bridge allows for enhanced copolymerization performance, resolving the contradiction between stability and productivity.
3Reliability
If conventional catalyst structures are used, then synthesis is straightforward, but polymerization reactivity and structural stability are insufficient
Solution Approach 1:
The patent merges multiple stabilizing features into a single integrated ligand structure: the dibenzothiophene-fused cyclopentadienyl unit combines the stability of fused aromatic rings with the reactivity-enhancing properties of the cyclopentadienyl motif. The amino group linked through the phenylene bridge further combines coordination capability with structural rigidity, achieving high polymerization reactivity despite increased molecular complexity.
Data Source
AI summary
The present invention provides a novel transition metal compound and a catalyst composition containing same, the transition metal compound having excellent polymer reactivity along with structural stability, thereby being capable of being usefully employed as a catalyst in preparing an olefin-based polymer, and especially, an olefin-based polymer having low density.