Stimulus-responsive covalent organic framework membranes for advanced separation and sensing

The dynamic adaptive properties of biological membranes in nature offer profound bionic insights for modern membrane science. Covalent organic frameworks (COFs), with their structural diversity, highly conjugated crystalline structures and exceptional mechanical robustness, are rapidly emerging as ideal candidates for smart membrane materials. Compared to conventional “static” COF membranes, the “dynamic” behavior of stimulus-responsive COF membranes endows them with versatile functionality and superior application adaptability. By bridging reticular chemistry and biomimetic intelligence, this review comprehensively summarizes the recent developments in stimulus-responsive COF membranes. We begin by highlighting the inherent advantages of COFs over other responsive membrane materials. To elucidate the stimulus-responsive principles of COF membranes, we systematically categorize them based on their responses to thermal, pH, light, electrical, and molecular stimuli, with a particular focus on their functional diversity. We then critically evaluate various preparation strategies, offering methodological guidance for introducing responsive sites and achieving defect-free membrane fabrication. Furthermore, we extensively demonstrate their breakthrough applications in challenging advanced separations and high-sensitivity sensing and optoelectronic devices. We conclude by discussing current bottlenecks and future directions. This review aims to provide forward-looking theoretical perspectives and engineering guidance for the rational design of next-generation adaptive framework membranes.