Functionalized Aluminum Reagents for Stereoregular Diene Polymerization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Heteroatom-functionalized aluminum reagents have been underutilized in polymer chemistry due to synthesis challenges and low chemoselectivity of mixed aluminum alkyls, limiting their application in chain transfer polymerization and functionalization of polymers.
Innovation Solution
Development of functionalized aluminum reagents with specific alkyl and phenylene groups, produced through reaction of olefinic silane with dialkyl aluminum hydride in the presence of a neodymium catalyst, which are used to activate lanthanide-based catalysts for conjugated diene polymerization, resulting in functionalized elastomers and rubber compositions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If heteroatom-functionalized aluminum reagents are used in chain transfer polymerization, then polymer chain end-functionalization can be achieved, but synthesis challenges and low chemoselectivity of mixed aluminum alkyls limit their practical application
Solution Approach 1:
The invention divides the complex functionalized aluminum reagent into simpler components: a dialkyl aluminum hydride precursor and an olefinic silane functionalizing agent. The synthesis proceeds in stages where the functional group is introduced separately rather than requiring direct synthesis of the complete functionalized aluminum alkyl, thereby simplifying manufacturing while maintaining functionalization capability
Solution Approach 2:
The patent uses dialkyl aluminum hydride as an intermediary species that facilitates the introduction of functional groups from olefinic silanes. This intermediary approach avoids the direct synthesis challenges of mixed aluminum alkyls by using a well-behaved aluminum hydride species that selectively reacts with the silane to transfer the functional group to the polymer chain end
2Adaptability or versatility
If mixed aluminum alkyls are used to achieve functionalization, then chain end-functionalization can be obtained, but chemoselectivity is low leading to unwanted side reactions
Solution Approach 1:
The invention introduces functional groups locally at the aluminum center through controlled reaction with olefinic silanes, rather than using mixed aluminum alkyls where functional groups are distributed throughout the molecule. This localized functionalization at the chain end maintains high chemoselectivity because the functional group is introduced at a specific site with controlled stoichiometry and reaction conditions
Solution Approach 2:
The patent performs preliminary functionalization of the aluminum reagent before polymerization by reacting dialkyl aluminum hydride with olefinic silanes to form the functionalized aluminum species in advance. This preliminary action ensures that the functional group is properly positioned and activated before chain transfer occurs, preventing side reactions and improving chemoselectivity
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 functionalized aluminum reagents effectively impart functionality to polymer chains, enabling stereoregular polymers with high cis or trans configurations, and are used in producing rubber compositions for tires, improving molecular weight control and uniformity.
Implementation Method 1
produced through reaction of olefinic silane with dialkyl aluminum hydride in the presence of a neodymium catalyst
Implementation Method 2
used to activate lanthanide-based catalysts for conjugated diene polymerization
Data Source
Figure 1~2
AI summary
A functionalized aluminum reagent of formula 1 is disclosed. In preferred embodiment, the functionalized aluminum reagent is one of A, B or C with Et = ethyl and Me = methyl: Also, 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 such a functionalized aluminum reagent is disclosed, and a method of making a functionalized aluminum reagent comprising the step of reaction of an olefinic silane with a dialkyl aluminum hydride in the presence of a neodymium catalyst is disclosed.