Self-Generating Zwitterionic Polyurethane Foam for Solar-Driven Water Evaporation in Complex Environments

Solar-driven water evaporation has attracted increasing attention as an environmentally friendly method of water purification/desalination. However, the presence of biofouling and oil-fouling agents in natural water induces channel plugging and significantly decreases its efficiency. In this study, a self-generating zwitterionic polyurethane foam (ZPF) is fabricated by grafting a silylated hydrolysis-induced zwitterionic telomer (Si-HIZ), further spraying TiN/PDMS on the top as a solar evaporation device. The TiN/PDMS serves as a photothermal converter, and the ZPF serves as a water pump. The foam exhibits excellent evaporation performance, with a water evaporation rate of 1.51 kg m^-2 h^-1 and a photothermal conversion efficiency of 98.56%. When used underwater, the foam forms a hydration layer that effectively inhibits biofilm formation in the channels, allowing solar-driven water evaporation to occur normally after cocultivating in a bacterial suspension (<i>Escherichia coli</i>, <i>Staphylococcus aureus</i>, and <i>Pseudomonas</i> sp.) for 4 days. Moreover, it exhibits good anti-oil-fouling performance (underwater-oil contact angle = 151°) and resists 20 wt % NaCl solutions in solar-driven water evaporation. These results demonstrate that hydrolysis-induced zwitterionic polymers are promising materials for designing water purification/desalination devices, introducing new avenues for applications in complex environments.