Ion-exchange membranes have been established for a variety of industrial applications, including energy and environmental technologies related to water treatment, fuel cells, and flow batteries. However, the limited tunability and adverse ion permeability-selectivity tradeoff exhibited by traditional ion-exchange membranes limit their development.
To address this limitation, researchers at UC Berkeley developed a new class of composite ion-exchange membrane materials incorporated with highly tunable porous aromatic frameworks (PAFs). The Berkeley researchers show that an assortment of PAF variants can be easily embedded into charged membranes, where the choice of PAF filler can be used to optimize the physical, ion transport, and adsorptive properties of the membrane according to their targeted application. Material characterizations indicate that numerous charged membranes embedded with PAFs exhibit excellent dispersibility, interfacial compatibility, structural flexibility, and pH stability. Proton conductivity and water uptake measurements also indicate that the exceptionally high porosity of PAFs enhances ion diffusion in membranes, while abundant, favorable PAF-polymer interactions decrease non-selective swelling pathways typically observed in highly charged ion-exchange membranes. Furthermore, adsorption experiments demonstrate that ion-selective PAFs can be embedded into charged membranes to tune the ion selectivity of the membrane and also enable their use as membrane adsorbents. Test show promise for technology to improve the general performance and tunability of ion-exchange membrane technologies.
This invention can be applied generally to various technologies that use ion-exchange membranes, or to adsorption processes where PAF adsorptive membranes detailed in this invention can be applied as membrane adsorbents. Examples of potential applications and variations of this invention include, but are not limited to, the following:
1. Cation- or anion-exchange membranes or bipolar membranes used for water purification or water desalination.
2. Fuel cell membranes (e.g., proton- or hydroxide-exchange membranes) with improved performance and stability compared to conventional neat membranes.
3. Reverse electrodialysis membranes for blue energy harvesting.
4. Charged membranes used for other general electrochemical applications that utilize a membrane, such as flow batteries.
5. Charged membranes used for selective ion separations.
6. Adsorptive membranes selective for targeted molecules, such as contaminants or high- value ions in water.
7. As a material variation, charged membranes can be incorporated with other PAF fillers not explicitly mentioned in this invention.
8. Similarly as a material variation, charged polymer matrices different from the sulfonated polysulfone matrix discussed in this report may be used with PAF incorporation. Other example charged ionomers that can be used with PAFs include perfluorinated sulfonic- acid (PFSA) ionomers and sulfonated polystyrene. Polymer matrices composed of multiple different charged polymers (e.g., bipolar membranes or copolymers) may also be incorporated with PAFs to yield improved membrane properties.
Ion-Exchange Membrane, Porous Polymer Network, Water Purification, Desalination, Fuel Cell Membrane