Armor strategy enables high temperature anti-swelling performance of 2D material based membranes by pre-protonation

Swelling significantly limits the performance and practical applications of two-dimensional (2D) membranes in aqueous environments. Here, we present an innovative "armor strategy" to enhance the anti-swelling performance of negatively charged 2D membranes, using vermiculite membranes (VM) as a model system. By spin-coating polyethyleneimine (PEI) onto the membrane surface and cross-linking with trimesoyl chloride (TMC), a robust protective layer was formed. The resulting VM-PEI-TMC membrane (VPTM) exhibits remarkable swelling resistance, with a swelling rate of only 0.83 %, compared to 23.70 % for unmodified VM. Practical applications of VPTM in ion sieving, dye rejection, and high-temperature operations demonstrated stable performance, with rejection rates of methylene blue (MB), rhodamine B (RB), and potassium ferricyanide (PF) exceeding 95 % at 80 °C. Furthermore, the universality of the armor strategy was established by applying it to graphene oxide membranes (GM), achieving a swelling rate reduction from 55.93 % to 5.02 %. These results highlight the versatility and effectiveness of the armor strategy, providing a promising pathway for developing high-performance, anti-swelling 2D membranes for environmental and energy applications.