As intelligent materials responsive to light, photomechanical hydrogels not only possess high-water content, excellent softness and biocompatibility, but also can accomplish various mechanical motions upon spatiotemporal stimulation of external light, which exhibit great potential in biomedical and underwater bionic fields. Molecular photoswitches have been used broadly in preparation of photomechanical hydrogels owing to their high photosensitivity and reversible molecular structure transformations induced by light. Herein, the current progress of photomechanical hydrogels based on typical molecular photoswitches such as spiropyran, azobenzene, and hexaarylbiimidazole (HABI) are introduced. Especially, as a promising building unit for photomechanical hydrogels, HABI has been highlighted due to the unique molecular structures and reversible photoswitching capability. HABI-derived polymer hydrogels demonstrate flexible mechanical behaviors upon localized light irradiation. The characteristics and challenges of photomechanical hydrogels based on molecular photoswitches are also prospected.

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基于分子光开关的光机械聚合物水凝胶

作为对光敏感的智能材料，光机械水凝胶不仅具有高含水量、优异的柔软性和生物相容性，而且可以在外部光的时空刺激下完成各种机械运动，在生物医学和水下仿生领域具有巨大的潜力。分子光开关由于其高光敏性和光诱导的可逆分子结构转变而被广泛用于制备光机械水凝胶。在此，介绍了基于螺吡喃、偶氮苯和六芳基联咪唑（HABI）等典型分子光开关的光机械水凝胶的研究进展。特别是作为一种有前途的光机械水凝胶构建单元，HABI 因其独特的分子结构和可逆的光开关能力而备受关注。HABI 衍生的聚合物水凝胶在局部光照射下表现出灵活的机械行为。还展望了基于分子光开关的光机械水凝胶的特点和挑战。