Non-dewetting Microporous Membranes via Crosslinked Ionomer Coating
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Solution Overview
Problem
There is a need for microporous membranes with improved non-dewetting characteristics that are easily wet with aqueous solutions using reduced organic solvents and maintain good flow characteristics.
Innovation Solution
Distributing a fluorocarbon liquid composition containing ionomers and crosslinkers onto a microporous membrane support, using a roller coater, to create a crosslinked coating that is non-dewetting and has high water permeability, with the ionomer concentration and equivalent weight influencing the flow loss and wettability properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a hydrophobic porous membrane is used for filtration, then chemical resistance and membrane strength are improved, but the membrane becomes difficult to wet with aqueous liquids and experiences dewetting during filtration
Solution Approach 1:
The patent applies parameter changes by modifying the surface energy of the hydrophobic membrane through treatment with fluorosurfactant solutions. This changes the wetting parameters of the membrane surface, enabling aqueous liquids to wet and penetrate the membrane pores without compromising the underlying hydrophobic structure and its chemical resistance properties.
Solution Approach 2:
The fluorosurfactant acts as an intermediary substance that mediates between the hydrophobic membrane surface and the aqueous liquid. The surfactant reduces surface tension and facilitates wetting by forming an intermediate layer that bridges the incompatibility between the hydrophobic membrane and hydrophilic liquid.
2Ease of operation
If wetting agents or surfactants are used to improve wettability, then ease of wetting is improved, but chemical purity of the filtered liquid may be compromised
Solution Approach 1:
The patent employs a disposable pre-wetting step using fluorosurfactant where the surfactant is applied to wet the membrane before filtration begins. The surfactant serves its purpose during the wetting phase and is subsequently displaced by the process liquid, minimizing its presence in the final filtered product.
Solution Approach 2:
The wetting with fluorosurfactant is performed as a preliminary action before the actual filtration process. This pre-treatment ensures the membrane is properly wetted and ready for filtration, while the subsequent process liquid flow displaces the surfactant, preventing contamination of the final product.
3Ease of operation
If pressure intrusion is used to wet tight pore membranes, then wettability is improved, but time consumption and cost increase and membrane rupture may occur
Solution Approach 1:
The patent changes the parameter of liquid surface tension by using fluorosurfactant with low surface tension properties. This allows the liquid to penetrate the tight pores at ambient pressure rather than requiring high pressure intrusion, thereby reducing time consumption and eliminating the risk of membrane rupture.
4Reliability
If hydrophobic porous membranes are used for filtration, then chemical resistance is improved, but gas pockets form on the membrane surfaces reducing filtration efficiency
Solution Approach 1:
The patent changes the surface energy parameters of the membrane by treating it with fluorosurfactant, which modifies the interfacial properties between the membrane, liquid, and gas phases. This prevents gas pocket formation by ensuring the membrane surface remains liquid-wetted during filtration while preserving the bulk membrane's chemical resistance.
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 resulting microporous membrane composites exhibit reduced flow loss and high water permeability, making them suitable for filtration applications in various manufacturing environments, with the ability to be wetted by solutions containing methanol and water without dewetting, even after autoclave treatment.
Implementation Method 1
Distributing a fluorocarbon liquid composition containing ionomers and crosslinkers onto a microporous membrane support, using a roller coater, to create a crosslinked coating that is non-dewetting
Implementation Method 2
Distributing a fluorocarbon liquid composition containing ionomers and crosslinkers onto a microporous membrane support, using a roller coater
Implementation Method 3
The resulting microporous membrane composites exhibit reduced flow loss and high water permeability, making them suitable for filtration applications
Implementation Method 4
The microporous membrane composites... with the ability to be wetted by solutions containing methanol and water without dewetting, even after autoclave treatment
Implementation Method 5
even after autoclave treatment
Data Source
AI summary
Microporous membrane composites that are non-dewetting are disclosed. These microporous membrane composites are wet with solutions of methanol and water and are non-dewetting following autoclave treatment in water. The microporous membrane composites comprise a microporous membrane support that is coated with a crosslinked ionomer comprising hydrophilic groups. Compared to the microporous membrane support, the microporous membrane composite has a flow loss on average in isopropyl alcohol of less than 82%.