▎ 摘　　要

NOVELTY - Preparing a superelastic double-layer photothermal gel with high mechanical strength, comprises (i) immersing the delignified wood blocks in a sodium hydroxide solution; stirring to obtain a suspension, cooling the suspension, filtering, and using deionized water to wash until neutral to obtain raw wood fibers; first freezing to obtain cellulose fibers; (ii) mixing polyvinyl alcohol with deionized water to obtain a polyvinyl alcohol aqueous solution; adding the cellulose fiber, adding a crosslinking agent and a catalyst after dispersion, and stirring to obtain a mixed solution; the mixed solution is divided into part A and part B, where light absorbing agent is added to part B; (iii) pouring part A into the mold and placing it in liquid nitrogen for directional freezing, pouring part B into the same mold, and directional freezing it in liquid nitrogen; then adding it together with the mold, freezing, taking out the gel and thawing, soaking in deionized water until neutral. USE - The superelastic double-layer photohydrothermal gel with high mechanical strength is used in solar-driven interfacial evaporation, photothermal seawater desalination, and sewage treatment (claimed). ADVANTAGE - The method provides super-elastic double-layer photo-thermal hydrogel with high mechanical strength and mechanical stability, and excellent steam generation, seawater desalination and sewage treatment performance. The salinity of the purified sea water is greatly reduced, it meets the requirement of the world health tissue to the safe application water, the fish tank detection test paper displays, the purified sewage can be used for the normal survival of the aquatic animal, it shows that the hydrogels water purification effect is excellent. DETAILED DESCRIPTION - Preparing a superelastic double-layer photothermal gel with high mechanical strength, comprises (i) immersing the delignified wood blocks in a sodium hydroxide solution with a concentration of 4-6%; stirring at 75-80°C for 4-6 hours to obtain a suspension, cooling the suspension to room temperature, filtering it, and using deionized water to wash until neutral to obtain raw wood fibers; first freezing at 15°C-30°C for 4-8 hours, and then vacuum freeze-drying at 40-65°C for 36-72 hours to obtain cellulose fibers; (ii) mixing polyvinyl alcohol with deionized water to obtain a polyvinyl alcohol aqueous solution with a mass percentage concentration of 2-4%; adding the cellulose fiber, adding a crosslinking agent and a catalyst after dispersion, and stirring to obtain a mixed solution; where the mass ratio of polyvinyl alcohol to cellulose fiber is 1-3:1; the volume ratio of crosslinking agent, catalyst to polyvinyl alcohol aqueous solution is 1:5:80-100; the mixed solution is uniformly divided into part A and part B, where light absorbing agent is added to part B; (iii) pouring part A into the mold and placing it in liquid nitrogen for directional freezing, then pouring part B into the same mold, and directional freezing it in liquid nitrogen until the gel is completely frozen; then adding it together with the mold, freezing at 15-30°C for 8 hours, taking out the gel and thawing at room temperature, soaking in deionized water until neutral. An INDEPENDENT CLAIM is included for a super-elastic double-layer photo-thermal hydrogel with high mechanical strength.