Phototropic Self‐Growing Hydrogels Enabled by a Tricyanofuran Derivatized Photoswitch

Phototropism is ubiquitous in plants that endows them directional movement and substantial growth toward light sources. Simultaneous replication of such phototropic movement and volumetric growth in synthetic polymers is important but currently remains challenging. Here, the molecular design of a photoswitchable tricyanofuran (TCF) based hydrogel is reported that can concurrently display such phototropic movement and self‐growth in water under stimulation of light and pH. The macroscale growth of the hydrogel originates directly from the volume swelling induced by charge rise of TCF upon isomerization, which dramatically facilicates water/nutrients diffusion into the network. As the growing rate under each stimulation is independently regulated, TCF hydrogels are successfully developed displaying heterogeneous growth accompanied with phototropic bending deformation by taking the advantage of the differential growing rates induced by light and pH. Importantly, the phototropic deformation direction after secondary polymerization growth can be reversibly switched between positive and negative states modulating light irradiation and pH conditions. This tunability enables biomimetic replication of natural light‐responsive systems. The work provides a novel molecular design strategy for advancing the development of biomimetic systems with capability of phototropic deformation and self‐growth.