High Performance Cation Exchange Membranes Synthesized via In-Situ Emulsion Polymerization Without Organic Solvents and Corrosive Acids

The synthesis of cation exchange membranes (CEMs) usually involves using organic solvents and/or sulfonation process. In this study, rapid and scalable synthesis of high performance CEMs is achieved without organic solvents and sulfonation. The synthesis is carried out via in-situ polymerization of lithium styrene sulfonate in porous support. Different preparation procedures are developed and optimized. Functional sulfonate groups were successfully loaded onto and into the membrane support, as verified by FTIR. Besides, water plays an important role during membrane synthesis. By reducing the amount of water used, the ratio of functional polymers to membrane support in the synthesized CEMs is increased. Therefore, the synthesized CEMs show increased ion exchange capacity (IEC). This is significant because it means that high IEC can be achieved without introducing cation exchange resins to the membranes. Finally, the synthesized membranes demonstrate excellent desalination performance, which is comparable to that of commercial membranes. This new methodology may shed new light on preparing CEMs in an efficient and eco-friendly way.