▎ 摘　　要

NOVELTY - A macromolecule hydrogel film with piezoelectric performance, comprises outer layer and inner layer, where the outer layer is a microporous hydro-hydrogel, and the inner layer is an insulating polymer layer. USE - The polymer hydrogel film is useful for seawater desalination, sewage treatment or water purification (claimed). ADVANTAGE - The hydrogel film: has excellent piezoelectric performance, water activation ability, strong hydration with water molecule, high flexibility, tensile strength, high power sensitivity, high output voltage, water activation capability and water-evaporating rate; can activate the water which is not influenced by the molecular chain in the hydrogel; and uses rich functional group to form three-dimensional network structure through chemical or physical action. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for: a preparing the polymeric hydrogel film, comprising placing the piezoelectric polymer film into a solution of a matrix material for polymer hydrogel, and then performing gelation treatment to obtain the final product, where the concentration of the matrix material solution for polymer hydrogel is less than 10 µg/ml and less than 200 µg/ml; and a use method of polymer hydrogel film, comprises introducing a photo-thermal conversion material into the polymer hydrogel film, then placing the polymer hydrogel film into seawater, sewage or water to be purified, where the photo-thermal conversion material can convert solar energy into heat energy under illumination, the converted heat energy can heat the water in the polymer hydrogel film, the hydrogen bonding effect in the water in the hydrogel is influenced by a hydrophilic molecular chain network of the hydrogel, and the energy required by evaporation is reduced, at the same time the piezoelectric polymer in the high-molecular hydrogel film can convert wave energy into electric energy, the water molecule motion the action of electric field is accelerated, and the energy needed by the evaporating is reduced.