PPS Porous Membranes via Water-Soluble Salt Leaching
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Solution Overview
Problem
Current methods for producing porous polymer articles, such as microporous membranes, often rely on solvents like NMP or DMF, which pose environmental concerns, and fail to achieve uniform ultrafine porosity and high mechanical strength, especially with polytetrafluoroethylene (PTFE) materials that have low tensile strength and non-uniform pore distribution.
Innovation Solution
A process using polyphenylene sulfide (PPS) polymer compositions with a water-soluble additive and reinforcing fillers, where the article is shaped and then contacted with water to dissolve the additive, creating an interconnected pore network with high porosity and mechanical strength, achieving pore sizes of 0.01 to 5 microns and porosity up to 60%.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If phase inversion methods using solvents like NMP or DMF are used to prepare porous membranes, then porosity and pore formation are achieved, but environmental problems and disposal issues are generated
Solution Approach 1:
The patent extracts and removes harmful solvent components from the membrane preparation process by using a water-soluble additive (salt) that can be easily dissolved and removed from the final product, replacing traditional organic solvents like NMP and DMF that cause environmental contamination and disposal problems
Solution Approach 2:
The patent changes the chemical parameter of the pore-forming agent from organic solvent to water-soluble inorganic salt, fundamentally altering the preparation process from solvent-based to water-based, thereby eliminating environmental harm while maintaining porosity formation capability
2Manufacturing precision
If template-leaching technique with PEG or PVA is used to prepare porous membranes, then porous structure is formed, but thermal stability is low due to degradation above 300°C
Solution Approach 1:
The patent uses a disposable water-soluble salt template that serves its pore-forming function and is then completely dissolved and removed, leaving no residual organic material that would limit thermal stability, unlike PEG or PVA that degrade above 300°C
Solution Approach 2:
The patent creates a composite structure during preparation where the polymer matrix is combined with water-soluble salt template, which after dissolution leaves a clean porous structure in the polymer without thermally unstable organic residues
3Reliability
If PTFE is used as the polymer material, then chemical resistance is achieved, but tensile strength is low and pore distribution is non-uniform
Solution Approach 1:
The patent changes the polymer material parameter from PTFE to PPS, fundamentally altering the mechanical properties while maintaining chemical resistance, enabling both high tensile strength and uniform pore distribution alongside chemical resistance
4Strength
If water-soluble additive is used to create pore network, then environmental friendliness and mechanical strength are improved, but the additive must be removed by water treatment
Solution Approach 1:
The patent extracts the water-soluble additive from the final product through simple water dissolution and filtration, a much easier removal process compared to removing organic solvents or thermally degrading PEG/PVA, making the additional step economically viable
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 method produces robust, ultrafine porous articles with exceptional mechanical strength, high temperature resistance, and uniform porosity, eliminating the environmental issues of solvent-based processes and providing improved mechanical and chemical resistance.
Implementation Method 1
contacting the article with water to dissolve the additive and create an interconnected pore network within the shaped article
Data Source
AI summary
The present invention relates to polymer compositions (C) for the preparation of porous article, notably microporous membranes or hollow fibers. More particularly, the present invention relates to a process of preparing a porous article from at least one polyphenylene sulfide (PPS) polymer with an additive and at least one reinforcing filler followed by a step of shaping the article and contacting the article with water to dissolve the additive and create an interconnected pore network within the shaped article.