Functionalized Elastomer Synthesis via Lanthanide Catalyst
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Solution Overview
Problem
Heteroatom-functionalized aluminum reagents have been underutilized in polymer chemistry due to synthesis drawbacks and low chemoselectivity, limiting their application in chain transfer reactions for functional group substitution in polymerization processes.
Innovation Solution
A method involving the use of a lanthanide-based coordination polymerization catalyst activated with a functionalized aluminum reagent to polymerize conjugated diene monomers, producing a functionalized elastomer with end-functionalization and stereoregularity, utilizing a neodymium carboxylate and organoboron salt catalyst system in a hydrocarbon solvent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If heteroatom-functionalized aluminum reagents are used as chain transfer reagents, then end-functionalization can be achieved, but synthesis difficulty and low chemoselectivity limit their practical application
Solution Approach 1:
The patent uses heteroatom-functionalized aluminum reagents as intermediary chain transfer agents that facilitate end-functionalization while the lanthanide catalyst maintains polymerization activity. The aluminum reagent acts as a mediator between the growing polymer chain and the desired end group, solving the contradiction by enabling precise functionalization through a specialized intermediary rather than direct synthesis challenges.
2Productivity
If heteroatom-functionalized aluminum reagents are used, then chain transfer reactions can occur, but low chemoselectivity reduces reaction efficiency
Solution Approach 1:
The patent applies local quality by using heteroatom-functionalized aluminum reagents with specific functional groups (amino, hydroxyl, carboxyl, etc.) that provide localized chemoselectivity at the chain transfer site. The functionalized aluminum reagent exhibits specific chemical affinity for certain polymer chain ends, enabling selective functionalization while maintaining overall reaction productivity.
3Ease of manufacture
If conventional aluminum alkyls are used as chain transfer reagents, then the process is simple, but molecular weight control and functionalization efficiency are insufficient
Solution Approach 1:
The patent changes the chemical parameters of the chain transfer reagent from conventional aluminum alkyls to heteroatom-functionalized aluminum reagents. This parameter change introduces functional groups that enable both molecular weight control through regulated chain transfer and end-functionalization, while maintaining process simplicity by using readily available functionalized aluminum compounds.
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 enables the production of functionalized elastomers with high cis or trans stereoregularity and end-functionalization, overcoming the limitations of traditional aluminum reagents and improving molecular weight control and uniformity in polymer synthesis.
Implementation Method 1
polymerizing a conjugated diene monomer in the presence of a lanthanide-based coordination polymerization catalyst
Implementation Method 2
Coordinative chain transfer polymerization (CCTP) using main group metals, i.e., a reversible chain transfer of polymeryl chains between chain growth active metal centers and chain growth inactive metal centers
Data Source
AI summary
The present invention is directed to a method of making a functionalized elastomer, comprising the step of polymerizing a conjugated diene monomer in the presence of a lanthanide-based coordination polymerization catalyst activated with a functionalized aluminum reagent of formula 1where R is a linear or branched alkane group containing 1 to 8 carbon atoms, and R1 is phenylene, or a linear or branched alkane diyl group containing 2 to 10 carbon atoms, or a combination of one or more phenylene groups and one or more linear or branched alkane diyl groups containing 1 to 10 carbon atoms; Q is of formula 2where R5, R6 and R7 are independently a linear or branched alkyl group containing 1 to 3 carbon atoms or a group of formula 3where R3 and R4 are independently phenyl or a linear or branched alkyl group containing 1 to 10 carbon atoms, or R3 and R4 taken together with the nitrogen atom represent a nitrogen containing heterocyclic group containing from 4 to 12 carbon atoms; or R5, R6 and R7 taken together with the silicon atom represent a structure of formula 4where R8 is C1 to C4 linear or branched alkanediyl and Z is N or a group of formula 5wherein R13 is C1 to C8 alkyl.