Rapid synthesis of polyzwitterionic hydrogel via frontal polymerization towards seawater desalination

The scarcity of freshwater has become a growing threat for human life, which sparks intense interests in hydrogel evaporator towards seawater desalination. Thus, methods allowing the rapid synthesis of high-performance hydrogel evaporator is highly desirable. In this work, we develop polyzwitterionic hydrogel by using zwitterionic monomer (2-Methacryloyloxy)ethyl]dimethyl-(3-sulfopropy, DMAPS) via frontal polymerization (FP) method, which is time- and energy-saving, allowing the preparation of hydrogels within several minutes. Meanwhile, the polyzwitterionic hydrogel shows higher swelling ratios and water evaporation performance than that prepared by common strategy. The polyzwitterionic hydrogel has anti-polyelectrolyte effects, showing electrostatic interaction between the anionic/cationic groups and salt ions, which is beneficial to the swelling capacity and evaporation performance in high salinity brines. Specially, by regulating the DMAPS content, a maximum seawater evaporation rate of 3.62 kg·m⁻²h⁻¹ under simulated sunlight and a maximum seawater evaporation rate of 3.57 kg·m⁻²h⁻¹ under natural sunlight are achieved, which holds great potentials in seawater desalination. This work proposes a polyzwitterionic hydrogel with high evaporation rate in seawater via a facile FP strategy, which enables the preparation of a variety of high-performance hydrogel evaporators in a rapid fashion.