Asymmetric Membrane Coating via Plasma Wettability Control
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Solution Overview
Problem
Existing methods for manufacturing asymmetric articles, such as membranes, are limited by the need for expensive or brittle polymers, and coating techniques often require substrates with nanoscale pores and high-viscosity coating materials, restricting the use of more inexpensive macroporous substrates and coating materials.
Innovation Solution
A method involving plasma or corona treatment of porous substrates to increase their wettability, allowing for the application and penetration of a polymeric coating into the substrate's porous structure, enabling the production of asymmetric composite articles with enhanced selectivity and flux at lower costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If coating solution is applied to porous substrate, then polymeric coating forms on substrate surface, but capillary forces cause entire substrate to imbibe coating material
Solution Approach 1:
The substrate surface is pre-treated with plasma or corona discharge before coating application. This preliminary action modifies the surface energy and wettability of the substrate, creating controlled hydrophilic regions that guide the coating solution to penetrate only to the desired depth while preventing uncontrolled imbibition throughout the entire substrate structure.
Solution Approach 2:
The patent changes the surface energy parameters of the substrate through plasma or corona treatment. This parameter modification allows precise control over the wettability gradient, enabling the coating solution to penetrate to a specific depth determined by the treatment conditions rather than being constrained by nanoscale pore size alone.
2Manufacturing precision
If nanoscale pore size substrates are used to prevent capillary imbibition, then coating depth is controlled, but substrate material options are limited
Solution Approach 1:
Instead of changing the physical pore size of the substrate, the patent changes the surface energy parameters through plasma or corona treatment. This allows macroporous substrates with larger pore sizes to be used while still achieving precise coating depth control through controlled wettability modification in the surface regions.
Solution Approach 2:
The plasma or corona treatment creates a gradient of surface properties from the treated surface region to the bulk substrate. The surface regions have modified wettability that controls coating penetration, while the bulk substrate maintains its original macroporous structure and material properties, enabling versatile material selection.
3Manufacturing precision
If high-viscosity coating materials are used to prevent substrate imbibition, then coating depth is controlled, but coating material options are restricted
Solution Approach 1:
The patent changes the wettability parameters of the substrate surface through plasma or corona treatment rather than relying on coating material viscosity. This parameter change allows the use of low-viscosity coating materials with better flow and penetration characteristics while still achieving controlled coating depth through the modified surface energy gradient.
Solution Approach 2:
The surface treatment creates localized regions with different wettability properties that control coating penetration independently of the bulk coating material viscosity. This allows selection of coating materials based on their chemical and functional properties rather than being constrained by viscosity requirements for depth control.
4Reliability
If asymmetric membrane is manufactured with selective layer atop porous layer, then high selectivity with high throughput is achieved, but expensive or brittle polymers are required
Solution Approach 1:
The plasma or corona treatment is applied as a preliminary step to modify the substrate surface properties before coating application. This enables the formation of a selective polymeric layer on inexpensive macroporous substrates, achieving high selectivity with high throughput without requiring expensive or brittle polymers for the entire membrane structure.
Solution Approach 2:
The patent creates a composite asymmetric membrane structure where a treated macroporous substrate is combined with a polymeric coating layer. The substrate provides mechanical strength and high throughput, while the coating layer provides selectivity, achieving reliable membrane performance at lower manufacturing costs.
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 enables the production of asymmetric composite articles with improved selectivity and high flux, suitable for applications like water filtration, desalination, and gas separations, while being more cost-effective and versatile in substrate and coating material usage.
Implementation Method 1
treating the porous substrate with a plasma treatment or a corona treatment from the first major surface to a depth of the porous structure
Implementation Method 2
treating the porous substrate with a plasma treatment or a corona treatment from the first major surface to a depth of the porous structure
Implementation Method 3
allowing for the application and penetration of a polymeric coating into the substrate's porous structure
Data Source
AI summary
Asymmetric articles are described including a porous substrate with two opposing major surfaces and a porous structure extending between the surfaces, and a polymeric coating on one of the major surfaces and extending into the porous structure to a depth of the porous structure. Methods for making an asymmetric composite article are also provided, including providing a porous substrate, treating the porous substrate with a plasma treatment or a corona treatment from one major surface to a depth of the porous structure between the two major surfaces. The method further includes applying a coating solution to the treated porous substrate and drying the coating solution to form a composite asymmetric composite article having a polymeric coating on one major surface and extending into the porous structure to the depth of the treated porous structure.