Ice-Confined Cryo-Polymerization of Sponge-Like Hydrogels with Self-Adapting Channel for Solar Water Purification

Polymer hydrogels are widely used in solar-driven water evaporation due to their controllable vaporization enthalpy, but the low water transport rates restrict their application. Here, a sponge-like polyacrylamide/carbon nanotube hydrogel is prepared by ice-confined cryo-polymerization, which possesses micro-size and non-swelling skeleton, and exhibits both hydrogel and sponge behaviors such as excellent squeezability and superior water transport capabilities about three orders of magnitude higher than that of conventional hydrogels. Moreover, the hydrogels can spontaneously regulate the size of internal channels to adjust the capillary force and thus they can support a water evaporation rate as high as 36.11 kg m^-2 h^-1 under collecting lens. Furthermore, the hydrogels show high water collection rate of 5.55 g g^-1 under fog flow and the collected water can be quickly released by squeezing. The ice-confined cryo-polymerization provides a new way to develop distinctive materials combining the advantage of both hydrogel and sponge.