Self-driven membrane filtration by core–shell polymer composites

Membrane filtration is an effective way of separation that usually requires an external driving force. Novel configurations simplifying the filtration process could offer extra versatility and enable separation in a broader context at different scales. This work presents a self-driven 3D filtration strategy based on core-shell polymer composites (CSPCs). The core is a hydrogel sphere that can spontaneously absorb similar to 50 times its own weight of water, while a polyamide film, as thin as similar to 7 nm, formed through interfacial polymerization serves as the separating shell. These flexible and easy-to-use CSPCs exhibit high-capacity and selective water absorption, which presents unique possibilities for applications such as concentrating biomedical and environmental samples for analyses and recovering valuable resources from waste streams.