Oxo-nitrogenated Iron Complex for High Cis-1,4 Polybutadiene
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Solution Overview
Problem
Current catalytic systems for the polymerization of conjugated dienes, such as polybutadiene and polyisoprene, struggle to achieve a mixed structure with a high content of 1,4-cis and 1,2 units or 1,4-cis and 3,4 units, which is desirable for specific industrial applications like tire production.
Innovation Solution
An oxo-nitrogenated iron complex with a specific general formula is used in a catalytic system, combined with co-catalysts like aluminum alkyls or aluminoxanes, to achieve a high content of 1,4-cis and 1,2 units in polybutadiene and 1,4-cis and 3,4 units in polyisoprene, optimizing the polymer structure for industrial uses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional catalytic systems (Ti, Co, Ni, Nd based) are used for polymerization, then high catalytic activity and stereospecificity are achieved, but the ability to produce polymers with mixed 1,4-cis and 1,2 unit content (≥90%) is limited
Solution Approach 1:
The invention changes the chemical parameters of the catalyst system by introducing iron-based complexes with specific ligands (β-diketonates, pyridines, or amines) and controlling the oxidation state (Fe(II) or Fe(III)). This parameter change enables the catalyst to produce polymers with ≥90% combined 1,4-cis and 1,2 unit content, resolving the contradiction between manufacturing precision and adaptability.
Solution Approach 2:
The invention uses composite catalytic systems combining iron complexes with organic ligands (β-diketonates, pyridines, or amines) and aluminum co-catalysts. This composite approach creates a synergistic effect that achieves both high stereospecificity for mixed microstructures and formulation flexibility, overcoming the limitations of conventional single-metal catalysts.
2Ease of manufacture
If iron-based catalysts with simple ligands are used, then the catalytic system is easier to prepare, but the stereospecificity and control over polymer microstructure are insufficient
Solution Approach 1:
The invention introduces organic ligands (β-diketonates, pyridines, or amines) as intermediaries that mediate between the iron center and the polymerization process. These ligands modify the electronic and steric properties of the iron complex, enabling precise control over polymer microstructure while maintaining relatively simple catalyst preparation procedures.
3Reliability
If conventional catalysts are used, then the polymerization process is well-established, but the ability to optimize rubber properties for specific applications (e.g., tire tread) is limited
Solution Approach 1:
The iron-based catalytic system exhibits multi-functionality by being able to produce polymers with different microstructures (high 1,4-cis content or high 1,2 unit content) depending on the specific ligand and reaction conditions used. This universality allows the same catalyst platform to be optimized for different rubber properties and applications while maintaining process stability.
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 catalytic system effectively produces polymers with a prevalent 1,4-cis and 1,2 or 1,4-cis and 3,4 unit content of ≥90%, meeting the industrial demand for specific rubber properties, such as improved tire tread performance.
Implementation Method 1
The present invention relates to an oxo-nitrogenated iron complex and to its use in a catalytic system for the (co)polymerization of conjugated dienes
Data Source
AI summary
An oxo-nitrogenated iron complex having general formula (I) or (II) wherein: R1 and R2 identical or different, represent a hydrogen atom; or are selected from linear or branched, optionally halogenated C1-C20, preferably C1-C15, alkyl groups, optionally substituted cycloalkyl groups, optionally substituted aryl groups; R3, identical or different, represent a hydrogen atom; or are selected from linear or branched, optionally halogenated C1-C20, preferably C1-C15, alkyl groups, optionally substituted cycloalkyl groups, optionally substituted aryl groups; X1 and X2, identical or different, represent a halogen atom such as, for example, chlorine, bromine, iodine; or are selected from linear or branched C1-C20, preferably C1-C15, alkyl groups, —OCOR4 groups or —OR4 groups wherein R4 is selected from linear or branched C1-C20, preferably C1-C15, alkyl groups. Said oxo-nitrogenated iron complex having general formula (I) or (II) can be advantageously used in a catalytic system for the (co)polymerization of conjugated dienes.