Yao Xin, Chen Hong, Qin Haili, Wu Qi-Hang, Cong Huai-Ping, Yu Shu-Hong
Anhui Province Engineering Research Center of Flexible and Intelligent Materials, School of Chemistry and Chemical Engineering, Hefei University of Technology, Hefei, P. R. China.
Institute of Innovative Materials, Department of Chemistry, College of Science, Southern University of Science and Technology, Shenzhen, P. R. China.
Nat Commun. 2024 Oct 26;15(1):9254. doi: 10.1038/s41467-024-53549-y.
Biological organisms can perform flexible and controllable multimodal motion under external stimuli owing to the hierarchical assembly of anisotropic structures across multiple length scales. However, artificial soft actuators exhibit the limited response speed, deformation programmability and movement capability especially in harsh environments because of insufficient anisotropic hierarchy and precision in structural design. Here, we report a programmed assembly directed confinement polymerization method for the fabrication of environmentally tolerant and fast responsive hydrogels with lamellar assembly-confined cellular structure interpenetrated with highly aligned nanopillars by the directional freezing-assisted polymerization in the predesigned anisotropic laminar scaffold. The obtained hydrogel exhibits ultrafast responsiveness and anisotropic deformation exposed to temperature/light/solvent stimulation, maintaining highly consistent responsive deformation capability in all-polarity solvents over 100 days of soaking. Moreover, the hydrogels implement photoactive programmable multi-gait locomotion whose amplitude and directionality are precisely regulated by the intrinsic structure, including controlled crawling and rotation in water and non-polar solvents, and 3D self-propulsion floating and swimming in polar solvents. Thus, this hydrogel with hierarchically ordered structure and dexterous locomotion may be suitable for flexible intelligent actuators serving in harsh solvent environments.
由于跨多个长度尺度的各向异性结构的分层组装，生物有机体能够在外部刺激下执行灵活且可控的多模态运动。然而，人工软致动器由于结构设计中各向异性层次和精度不足，其响应速度、变形可编程性和运动能力有限，尤其是在恶劣环境中。在此，我们报道了一种程序化组装定向限域聚合方法，用于制备具有环境耐受性和快速响应性的水凝胶，该水凝胶具有层状组装限制的细胞结构，并通过在预先设计的各向异性层状支架中进行定向冷冻辅助聚合，与高度排列的纳米柱相互贯穿。所获得的水凝胶在温度/光/溶剂刺激下表现出超快响应性和各向异性变形，在浸泡超过100天的所有极性溶剂中保持高度一致的响应变形能力。此外，水凝胶实现了光活性可编程多步态运动，其幅度和方向性由内在结构精确调节，包括在水和非极性溶剂中的可控爬行和旋转，以及在极性溶剂中的三维自推进漂浮和游动。因此，这种具有层次有序结构和灵活运动的水凝胶可能适用于在恶劣溶剂环境中工作的柔性智能致动器。
