High Vinyl Block Copolymer Polar Modifier System
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for producing block copolymers of conjugated diene and vinyl aromatic monomers using polar modifiers face challenges in achieving high levels of pendant vinyl double bonds, narrow molecular weight distribution, and low vinylcyclopentane content, particularly at elevated temperatures, which affects the thermal and dynamic properties of thermoplastic elastomer compositions.
Innovation Solution
A polar modifier system comprising ternary blends such as DTHFP/BDMAEE/SMT, ETE/BDMAEE/SMT, TMEDA/BDMAEE/SMT, and DMTHFMA/BDMAEE/SMT is used to produce block copolymers with high 1,2-vinyl and 3,4-vinyl bond additions, maintaining low vinylcyclopentane content and unimodal narrow molecular weight distribution, even at competitive production rates and with reduced temperature sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If polar modifiers are used to increase pendant vinyl double bond content in block copolymers, then the mechanical properties and flow properties are improved, but vinylcyclopentane content increases and molecular weight distribution widens
Solution Approach 1:
The patent introduces a specific polar modifier system comprising a Lewis base (TMEDA or DMTHFMA) in combination with a sodium alkoxide (SMT or STA) as intermediary agents that mediate the polymerization process. This modifier system selectively promotes 1,2-vinyl addition while suppressing vinylcyclopentane formation, resolving the contradiction between achieving high vinyl content and maintaining low VCP content
Solution Approach 2:
The patent changes the chemical parameters of the polymerization system by introducing specific polar modifiers at controlled concentrations (0.1-1.0 equivalents of Lewis base and 0.01-0.1 equivalents of sodium alkoxide per mole of diene). This parameter change transforms the polymerization pathway to favor desired microstructure while avoiding harmful side reactions
2Manufacturing precision
If polar modifiers are used to achieve high vinyl content, then the mechanical properties improve, but molecular weight distribution widens due to chain transfer reactions
Solution Approach 1:
The Lewis base polar modifier acts as an intermediary that stabilizes the propagating carbanion without promoting chain transfer reactions. This mediation allows high vinyl content to be achieved while maintaining narrow molecular weight distribution (PDI < 1.1), resolving the contradiction between composition precision and compositional stability
3Manufacturing precision
If conventional polar modifiers are used to achieve high 1,2-vinyl content, then vinyl content increases, but polymerization rate decreases and cooling requirements increase
Solution Approach 1:
The patent changes the chemical environment by introducing a Lewis base that modifies the reactivity of the organolithium initiator and propagating species. This parameter change enables high 1,2-vinyl content to be achieved at faster polymerization rates with reduced heat generation, resolving the contradiction between precision and productivity
Solution Approach 2:
The patent converts the typically harmful effect of heat generation during polymerization into a benefit by using the Lewis base-modified system that reduces exothermicity. The reduced cooling requirements and faster rates transform what was a limitation into an advantage for industrial production
4Productivity
If polymerization temperature is increased to improve production rate, then productivity increases, but the capability of polar modifiers to promote 1,2 or 3,4-addition drops significantly
Solution Approach 1:
The Lewis base polar modifier serves as a temperature-resilient intermediary that maintains its ability to promote vinyl addition even at elevated temperatures (0-50°C). This intermediary effect resolves the contradiction between productivity and precision by providing temperature-insensitive vinyl addition capability
Solution Approach 2:
The patent changes the temperature parameter range to 0-50°C, which is higher than conventional low-temperature processes, while simultaneously introducing the Lewis base modifier to compensate for the reduced vinyl addition capability at higher temperatures. This combined parameter change resolves the contradiction between production rate and vinyl content
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 results in block copolymers with enhanced mechanical properties, improved flow properties, and high clarity, enabling the production of thermoplastic elastomers with superior balance of rheological and mechanical properties, suitable for various applications including medical devices, automotive parts, and adhesives.
Implementation Method 1
Batch and semi-batch processes of alkyllithium initiated anionic polymerization in aliphatic hydrocarbon solution are versatile technologies to produce block copolymers of conjugated diene monomers, such as butadiene and isoprene, and vinyl aromatic monomers, such as styrene.
Implementation Method 2
Many polar modifiers have been disclosed that can influence conjugated diene mode of addition towards this kind of microstructure, nevertheless, a very common drawback is that their capability to promote 1,2 or 3,4-addition drops significantly when polymerization temperature rises.
Implementation Method 3
Typical operating temperatures and limited heat removal capacity of industrial processes rule out most options of polar modifiers to get 1,2-vinyl contents higher than 80 wt % on a conjugated diene basis.
Data Source
AI summary
A styrenic block copolymer composition comprising a hydrogenated high vinyl block copolymer and/or a high vinyl styrene-ethylene/butylene-styrene (SEBS) copolymer is mixed with a thermoplastic resin to form a thermoplastic elastomer (TPE) composition. TPE compositions comprising hydrogenated high vinyl block copolymers with relatively high molecular weight compounded with polypropylene provide compounds with high flow properties, high clarity, low haze, which exhibit higher tensile strength and elongation at break than prior art compositions. High vinyl SEBS TPE compositions exhibiting high melt flow can be used in many applications, either as a neat polymer or in a compound, to produce medical devices including tubes, over molding applications for personal care, soft touch materials, automotive parts, blown film, dipped goods, materials with oxygen absorbing capability, oil gel compositions, radiation curable hot melt adhesive compositions, hot melt pressure sensitive adhesives, sealant formulations, elastic films, fibers and non-woven compounds.