Cross-linked Sulfonated Polymers for Wet Mechanical Stability
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Solution Overview
Problem
There is a need for improved sulfonated styrenic block copolymer compositions with enhanced properties, particularly for applications in water purification and antimicrobial uses, where exposure to wet conditions poses challenges for durability and effectiveness.
Innovation Solution
A composition comprising sulfonated styrenic block copolymers with an ion exchange capacity of at least 0.5 meq/g, cross-linked with a cross-linking agent, metal cation, or non-sulfonated polymer, exhibiting improved mechanical properties such as toughness and tensile stress in wet conditions, achieved through specific sulfonation and cross-linking processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sulfonated styrenic block copolymer is used in water purification applications, then ion exchange capacity is improved, but mechanical stability in wet conditions deteriorates
Solution Approach 1:
The patent applies composite materials by combining sulfonated styrenic block copolymer with cross-linking agents (such as polyols, polyisocyanates, or metal cations) to create a cross-linked network structure. This composite approach maintains the high ion exchange capacity of the sulfonated polymer while the cross-linked framework provides mechanical stability in wet conditions, resolving the contradiction between ion exchange performance and mechanical durability.
Solution Approach 2:
The patent utilizes parameter changes by controlling the degree of sulfonation and the cross-linking density to optimize both ion exchange capacity and mechanical stability. By adjusting these parameters, the material achieves the required ion exchange performance while maintaining structural integrity in aqueous environments through the cross-linked network.
2Strength
If cross-linking is increased to improve mechanical strength, then toughness in wet state is improved, but ion exchange capacity may be reduced
Solution Approach 1:
The patent optimizes the balance between cross-linking density and ion exchange capacity by carefully controlling the amount and type of cross-linking agent used. The cross-linking is designed to provide sufficient mechanical strength and toughness in wet states while maintaining adequate spacing and accessibility of sulfonate groups for ion exchange functions, thus resolving the trade-off between mechanical strength and ion exchange capacity.
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 cross-linked sulfonated styrenic block copolymer films demonstrate enhanced stability and performance in aqueous environments, maintaining mechanical integrity and antimicrobial efficacy, suitable for advanced water purification and antimicrobial applications.
Implementation Method 1
the SSBC is obtained by sulfonation of a styrenic block copolymer (SBC) precursor
Implementation Method 2
a sufficient amount of at least one compound which reacts with the SSBC forming a cross-linked SSBC
Implementation Method 3
having an ion exchange capacity (IEC) of at least 0.5 meq/g
Data Source
AI summary
A composition is disclosed comprising a sulfonated styrenic block copolymer (SSBC) having an ion exchange capacity (IEC) of at least 0.5 meq/g; and at least one compound which reacts with the SSBC forming a cross-linked SSBC. The compound is selected from: (i) a cross-linking agent, (ii) a metal cation, and (iii) a non-sulfonated polymer. A film prepared from the composition containing the cross-linked SSBC has a toughness in wet state measured after 1 week of 1.2 to 8 MJ/m3; and a tensile stress in wet state measured after 1 week of 3.2 to 8 MPa, according to ASTM D412. The film can be used as a water purification membrane or an antimicrobial protection layer.