Anionic Polymerization Initiator for Conjugated Diene Rubber
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Solution Overview
Problem
Current anionic polymerization methods require additional equipment for solvent separation and are prone to side reactions due to high reactivity, especially when using alkyl lithium initiators with polar solvents like tetrahydrofuran, leading to undesirable branch structures and increased complexity in polymerization processes.
Innovation Solution
The use of 1-(diethylaminomethyl)-2,4,6-trimethylbenzene or 1-(diisopropylaminomethyl)-2,4,6-trimethylbenzene as anionic polymerization initiators, which reduce the need for polar solvents and enhance dissociation in non-polar solvents, thereby minimizing side reactions and improving molecular weight control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If alkyl lithium is used as anionic polymerization initiator with polar solvent, then polymerization reactivity is increased, but additional equipment is required for solvent separation and recovery
Solution Approach 1:
The patent changes the chemical structure of the initiator from simple alkyl lithium to a complex organic lithium compound with specific functional groups (amino, hydroxyl, or carboxyl) that can coordinate to lithium cation. This parameter change allows the initiator to function effectively in non-polar solvents, eliminating the need for polar solvent addition and subsequent separation equipment.
Solution Approach 2:
The patent extracts the polar solvent requirement from the polymerization system by incorporating polar coordinating groups directly into the initiator molecule. This removes the need for external polar solvents like tetrahydrofuran or dimethylether, thereby eliminating the associated separation and recovery equipment requirements.
2Productivity
If butyllithium is used as anionic polymerization initiator, then polymerization activity is high, but side reactions occur causing branch structures
Solution Approach 1:
The patent introduces specific functional groups (amino, hydroxyl, or carboxyl) at particular positions in the initiator molecule that can coordinate to lithium cation. This local modification creates a more controlled reactivity pattern that maintains polymerization activity while suppressing unwanted side reactions that cause branching.
Solution Approach 2:
The coordinating groups (amino, hydroxyl, or carboxyl) act as intermediaries between the lithium cation and the polymerization mechanism. These groups mediate the interaction in a way that controls reactivity and prevents direct, uncontrolled reactions that lead to branch structures.
3Productivity
If polar solvent is added to prevent initiator aggregation, then reactivity is increased, but solubility in non-polar solvents decreases
Solution Approach 1:
The patent creates a composite initiator structure combining non-polar hydrocarbon chains with polar coordinating groups. This composite molecular structure allows the initiator to be soluble in non-polar solvents while maintaining the polar groups necessary for lithium cation coordination and high reactivity.
Solution Approach 2:
The initiator molecule has different local regions with different polarities: non-polar hydrocarbon chains provide solubility in non-polar solvents, while the amino, hydroxyl, or carboxyl groups provide local polarity for lithium coordination. This spatial separation of functional requirements resolves the contradiction between solubility and reactivity.
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
This approach eliminates the need for polar solvent mixing, increases initiator activity, and enhances solubility in non-polar solvents, resulting in better control over molecular weight and distribution, and improved dispersibility of silica reinforcing agents in rubber, thus simplifying the polymerization process and enhancing polymer properties.
Implementation Method 1
a nitrogen atom-containing alkyl group, which is able to coordinate to the lithium cation, is chemically connected to the structure of the initiator
Implementation Method 2
the initiator can have high activity because of the high ability to dissociate in a non-polar solvent
Data Source
AI summary
Disclosed are an anionic polymerization initiator, which is a reaction product of an organometallic compound and a compound including an alkyl chain having a tertiary amino functional group, and a method of preparing a conjugated diene-based copolymer using the same.