Self-Wetting Membrane Copolymer Design
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Solution Overview
Problem
Aromatic hydrophobic polymers, such as polysulfone and polyethersulfone, used in membrane production are inherently non-wettable by water, and existing methods to improve surface wettability, like blending with hydrophilic additives or coating, often result in instability or pore modification, leading to limited membrane effectiveness over extended use.
Innovation Solution
A self-wetting porous membrane is created by incorporating a copolymer of formula A-B or A-B-A, where A is a hydrophilic segment with specific monomers and B is an aromatic hydrophobic polymeric segment linked through an amidoalkylthio group, providing high water wettability and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydrophilic additives are blended into the porous membrane, then surface wettability is improved, but the additives leach out over prolonged use
Solution Approach 1:
The patent combines the hydrophilic polymer and hydrophobic membrane matrix into a single copolymer structure where hydrophilic segments are covalently bonded to hydrophobic segments. This merging eliminates the interface between separate components, preventing leaching while maintaining wettability.
Solution Approach 2:
The wetting function is built into the membrane structure during manufacturing by incorporating hydrophilic segments within the copolymer chains. This preliminary integration ensures that the wettability is inherent to the membrane structure itself rather than relying on separate additives that could leach out later.
2Reliability
If a hydrophilic polymer is coated and crosslinked on the membrane surface, then surface wettability is improved, but the membrane pores shrink or are modified
Solution Approach 1:
The copolymer structure creates local hydrophilic zones within the hydrophobic membrane matrix. The hydrophilic segments are distributed throughout the membrane at the molecular level, providing wettability enhancement without forming a continuous coating layer that would block pores.
Solution Approach 2:
The invention maintains the porous structure of the membrane by incorporating the copolymer in a way that does not fill or block the pores. The copolymer integrates with the membrane matrix while preserving the void spaces necessary for filtration and flow.
3Reliability
If hydrophilic additives are used to improve wettability, then water contact is enhanced, but the additives do not distribute uniformly
Solution Approach 1:
The copolymer structure ensures homogeneous distribution of hydrophilic functionality throughout the membrane. Since the hydrophilic segments are covalently bonded within the copolymer chains that are uniformly distributed in the membrane matrix, the wettability enhancement is uniform across the entire membrane surface.
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 membrane exhibits high critical wetting surface tension, maintaining stability and compatibility with the aromatic hydrophobic polymer, ensuring minimal leaching and uniform distribution of the wetting additive, resulting in enhanced water wettability and prolonged usability.
Implementation Method 1
A is a hydrophilic segment comprising a polymerized monomer or mixture of monomers... The self-wetting porous membrane of the invention has high water wettability as evidenced by its high critical wetting surface tension
Implementation Method 2
Aromatic hydrophobic polymers such as polysulfone and polyethersulfone... thermal and oxidative stability, excellent strength and flexibility, resistance to extreme pHs
Data Source
Figure 1
AI summary
Disclosed is a self-wetting porous membrane comprising an aromatic hydrophobic polymer such as polysulfone and a wetting agent comprising a copolymer of formula A-B or A-B-A, wherein A is a hydrophilic segment comprising a polymerized monomer of the formula (I): CH2=C(R1)(R2), wherein R1 and R2 are as described herein, and B is an aromatic hydrophobic polymeric segment, wherein segments B and A are linked through an amidoalkylthio group. Also disclosed is a method of preparing a self-wetting membrane comprising casting a solution containing an aromatic hydrophobic polymer and the wetting agent, followed by subjecting the cast solution to phase inversion. The self-wetting porous membrane finds use in hemodialysis, microfiltration, and ultrafiltration.