Hydrophilic Filter Membrane Grafting Ionic Groups
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Solution Overview
Problem
Existing methods for grafting ionic groups onto hydrophilic polymers, such as those used in filter membranes, are ineffective for hydrophilic surfaces like nylon, leading to insufficient attachment of charged functionalities, which hampers the improvement of non-sieving filtration performance without compromising fluid flow properties.
Innovation Solution
A technique involving the use of a hydrophobic photoinitiator applied in solution to a hydrophilic polymer surface, followed by re-wetting with a monomer solution and exposure to electromagnetic radiation, allows for the effective grafting of ionic groups onto the polymer, enhancing non-sieving filtration capabilities without significantly affecting fluid flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing grafting methods are used on hydrophilic polymer surfaces, then the process is simple, but the attachment of ionic groups is insufficient
Solution Approach 1:
A hydrophobic photoinitiator is used as an intermediary substance to enable effective grafting of ionic groups onto hydrophilic polymer surfaces. The photoinitiator mediates the interaction between the hydrophilic polymer and the monomer solution, allowing successful attachment of ionic groups that would otherwise be insufficient with conventional direct grafting methods.
Solution Approach 2:
The method changes the chemical parameters of the grafting process by introducing a hydrophobic photoinitiator and using a monomer solution with specific composition. This parameter change transforms the ineffective direct grafting process into an effective multi-step process involving photoinitiator application, monomer solution re-wetting, and electromagnetic radiation exposure.
2Reliability
If ionic groups are grafted onto the polymer to improve non-sieving filtration, then filtration performance improves, but fluid flow properties may be compromised
Solution Approach 1:
The grafting process applies ionic groups locally to the polymer surface through controlled exposure to monomer solution and electromagnetic radiation. This local modification enhances non-sieving filtration performance at the surface level while preserving the bulk polymer's porosity and fluid flow characteristics.
Solution Approach 2:
The method uses controlled partial grafting where ionic groups are attached to enhance filtration performance without excessive modification that would block pores. The monomer solution concentration and exposure time are optimized to achieve sufficient ionic group attachment while maintaining adequate fluid flow through the membrane.
3Reliability
If hydrophobic photoinitiator is applied to hydrophilic polymer surface, then ionic group attachment improves, but additional process steps are required
Solution Approach 1:
The hydrophobic photoinitiator is applied to the hydrophilic polymer surface as a preliminary step before introducing the monomer solution. This preliminary action prepares the surface by creating favorable conditions for subsequent monomer attachment, enabling effective ionic group grafting through a systematic multi-step process.
Solution Approach 2:
The process maintains continuity of useful action by sequentially applying the photoinitiator, then rewetting with monomer solution, and finally exposing to electromagnetic radiation. Each step builds on the previous one, creating a continuous grafting process that achieves effective ionic group attachment without interrupting the overall objective.
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 enables a significant improvement in non-sieving filtration performance, as measured by dye-binding capacity and particle retention, while maintaining or slightly increasing the flow rate through the filter membrane.
Implementation Method 1
exposing the surfaces to electromagnetic radiation to cause the ionic groups to become grafted to the hydrophilic polymer
Data Source
AI summary
Described are hydrophilic polymers (including in the form of a filter membranes that includes hydrophilic polymer) having pendant ionic groups; to methods of making the hydrophilic polymer with pendant ionic groups and derivative membranes and filters; and to method of using the filter membranes for filtering a fluid such as a liquid chemical to remove unwanted material from the fluid.