Pyridyl Iron(III) Catalyst for Diene Microstructure Control
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Solution Overview
Problem
Current catalytic systems for the stereospecific polymerization of conjugated dienes, such as polybutadiene and polyisoprene, lack the ability to modulate the microstructure effectively to meet diverse end-use requirements, particularly in producing tires, where specific microstructural compositions are needed.
Innovation Solution
A catalytic system comprising a pyridyl iron (III) complex in combination with organo-aluminum derivatives, allowing for the modulation of 1,4-cis, 1,4-trans, and 1,2 unit content in polybutadiene and 1,4-cis, 1,4-trans, and 3,4 unit content in polyisoprene, thereby tailoring the polymer microstructure for various applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional catalytic systems (Ti, Co, Ni, Nd based) are used for stereospecific polymerization of conjugated dienes, then high catalytic activity and stereospecificity are achieved, but the ability to modulate microstructure to meet diverse end-use requirements is limited
Solution Approach 1:
The patent applies parameter changes by systematically varying the ligand structure (L1-L8) on the iron (III) center, changing the electronic and steric parameters of the catalyst. This enables modulation of the polymer microstructure (1,4-cis, 1,4-trans, and 1,2 unit content) without changing the fundamental catalytic system type, thus achieving adaptability while maintaining a consistent catalytic framework.
Solution Approach 2:
The patent employs composite catalytic systems combining iron (III) complexes with specific pyridine ligands (L1-L8) and aluminum co-catalysts. This composite approach creates a synergistic system where the iron center provides catalytic activity while the tailored ligand environment controls stereoselectivity, enabling microstructure modulation that neither component could achieve alone.
2Adaptability or versatility
If iron (Fe) based catalysts are used for (co)polymerization of conjugated dienes, then catalytic activity is provided, but the microstructure control and versatility for different applications are insufficient
Solution Approach 1:
The patent applies local quality by designing specific ligand environments (L1-L8) around the iron (III) center that create localized electronic and steric conditions. These local modifications at the catalyst active site directly influence the stereoselectivity and microstructure of the polymer product, enabling precise control over 1,4-cis, 1,4-trans, and 1,2 unit content.
Solution Approach 2:
The patent implements dynamics by creating a series of iron (III) complexes with ligands having different steric and electronic properties (L1-L8). This dynamic set of catalysts allows selection and optimization for different desired microstructures and applications, providing versatility while maintaining precise manufacturing control through systematic ligand design.
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
Enables the production of conjugated diene (co)polymers with tailored microstructures, enhancing their suitability for specific end-uses like tire manufacturing by providing a mixed structure with variable 1,4-cis, 1,4-trans, and 1,2 unit content in polybutadiene and 1,4-cis, 1,4-trans, and 3,4 unit content in polyisoprene.
Implementation Method 1
a catalytic system comprising: (a) at least one pyridyl iron (III) complex ; (b) at least one co-catalyst selected from organo-aluminum derivatives
Data Source
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AI summary
A process for preparing conjugated diene (co)polymers comprising polymerizing at least one conjugated diene in the presence of a catalytic system comprising: (a) at least one pyridyl iron (III) complex having general formula (I) or (II): wherein: - R1, R2, R3 and R4, 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; - R5 represents a hydrogen atom, or is selected from linear or branched, optionally halogenated C1-C20, preferably C1-C15, alkyl groups, optionally substituted cycloalkyl groups, optionally substituted aryl groups; - X, 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, -OCOR6 groups or -OR6 groups wherein R6 is selected from linear or branched C1-C20, preferably C1-C15, alkyl groups. - n is 3; (b) at least one co-catalyst selected from organo-aluminum derivatives, preferably from: (b1) aluminum compounds having general formula (III): Al(R7)(R8)(R9) (IIl) wherein R7 represents a hydrogen atom, or is selected from linear or branched C1-C20 alkyl groups, cycloalkyl groups, aryl groups, alkylaryl groups, arylalkyl groups, alkoxy groups; R8 and R9, identical or different, are selected from linear or branched C1-C20 alkyl groups, cycloalkyl groups, aryl groups, alkyaryl groups, arylalkyl groups; (b2) aluminoxanes having general formula (IV): (R10)2-Al-O-[-AI(R11)-O-]m-AI-(R12)2 (IV), wherein R10, R11 and R12, identical or different, represent a hydrogen atom, or a halogen atom such as chlorine, bromine, iodine, fluorine; or are selected from linear or branched C1-C20 alkyl groups, cycloalkyl groups, aryl groups, said groups being optionally substituted with one or more silicon or germanium atoms; and m is an integer ranging from 0 to 1000; (b3) partially hydrolyzed organo-aluminum derivatives; (b4) haloaluminum alkyls having general formula (V) or (VI): AI(R13)p(X')3-p (V) AI2(R13)q(X')3-q (VI) wherein p is 1 or 2; q is an integer ranging from 1 to 5; R13, identical or different, are selected from linear or branched C1-C20 alkyl groups; X' represents a chlorine or bromine atom, preferably chlorine; provided that said co-catalyst (b) is not selected from organo-boron derivatives.