Anion-Exchange Composite Membrane Resolving Brittleness and Cost
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Solution Overview
Problem
Conventional ion-exchange membranes face challenges in achieving high mechanical strength, chemical resistance, and low production costs while maintaining effective ion exchange capacity and conductivity, due to issues with brittleness, phase separation, and increased complexity in manufacturing processes.
Innovation Solution
A vinylbenzyl-styrene anion-exchange composite membrane is developed, incorporating a copolymer with vinylbenzyl trialkylammonium salt, styrene, divinylbenzene, an olefin additive, a plasticizer, and a polyvinyl halide polymer, which is impregnated into a fabric support, allowing for improved mechanical properties, ion exchange capacity, and reduced electrical resistance through a simplified production method.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If bulk polymerization is used to prepare ion-exchange membrane, then manufacturing cost is reduced, but mechanical strength is lowered due to increased brittleness
Solution Approach 1:
The invention uses a composite structure consisting of a polyvinyl halide polymer base film combined with a vinylbenzyl-divinylbenzene copolymer layer containing ion-exchange groups. This composite approach allows the membrane to achieve both mechanical strength from the polymer matrix and ion-exchange functionality, resolving the contradiction between ease of manufacture and mechanical strength.
2Reliability
If latex method is used to prepare ion-exchange membrane, then ion exchange capacity is improved, but mechanical properties and electrochemical characteristics are reduced due to emulsifier remaining
Solution Approach 1:
The invention eliminates the need for emulsifiers by using a bulk polymerization method instead of latex polymerization. The ion-exchange groups are introduced through quaternary amination of the vinylbenzyl-divinylbenzene copolymer prepared by bulk polymerization, thereby extracting the harmful emulsifier component while maintaining ion-exchange capacity.
3Strength
If paste method is used to prepare ion-exchange membrane, then mechanical and electrochemical properties are improved, but process complexity increases and production cost rises
Solution Approach 1:
The invention combines the polymerization and ion-exchange group introduction steps into a unified bulk polymerization process followed by quaternary amination. This merging of processes simplifies the overall manufacturing procedure compared to the paste method, reducing process complexity while maintaining mechanical properties.
4Ease of manufacture
If conventional copolymerization is used without support, then manufacturing simplicity is improved, but mechanical strength is insufficient due to brittleness
Solution Approach 1:
The invention creates a composite membrane structure where the polyvinyl halide polymer provides mechanical strength and structural support, while the vinylbenzyl-divinylbenzene copolymer layer provides ion-exchange functionality. This composite approach maintains manufacturing simplicity while solving the brittleness problem.
5Reliability
If ion-exchange groups are introduced to improve ion exchange capacity, then separation performance is enhanced, but brittleness increases and chemical resistance decreases
Solution Approach 1:
The invention introduces ion-exchange groups locally through quaternary amination of the vinylbenzyl-divinylbenzene copolymer layer, rather than throughout the entire membrane structure. This localized introduction maintains the mechanical integrity and chemical resistance of the bulk polyvinyl halide polymer while providing sufficient ion-exchange capacity at the functional layer.
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 composite membrane exhibits excellent ion exchange capability, ionic conductivity, mechanical strength, and chemical resistance, with reduced brittleness and lower production costs, facilitating efficient and cost-effective water treatment and purification processes.
Implementation Method 1
a vinylbenzyl-styrene anion-exchange composite membrane which comprises a copolymer containing a vinylbenzyl trialkylammonium salt repeating unit, a styrene repeating unit, and a divinylbenzene derived repeating unit
Implementation Method 2
an anion-exchange membrane has a strong basic quaternary ammonium group (—NH3+) mostly as an ion-exchangeable group
Data Source
AI summary
The present invention provides a anion-exchange composite membrane comprising a copolymer containing a vinylbenzyl trialkylammonium salt repeating unit, a styrene repeating unit and a divinylbenzene derived repeating unit; an olefin additive; a plasticizer; and a polyvinyl halide polymer. The anion-exchange composite membrane comprising a copolymer containing a vinylbenzyl trialkylammonium salt repeating unit, a styrene repeating unit and a divinylbenzene derived repeating unit; an olefin additive; a plasticizer; and polyvinylidene fluoride of the present invention not only displays low electrical resistance, excellent ion exchange capability, excellent ionic conductivity, excellent mechanical properties, excellent chemical properties, and processability, but also is easy to regulate its ion exchange capacity and ionic conductivity. Also, the composite membrane of the invention is easier to produce and cheaper to manufacture than the conventional anion-exchange composite membrane.