Liu Kangkang, Zhang Yue, Cao Heqing, Liu Haonan, Geng Yuhui, Yuan Wenhua, Zhou Jian, Wu Zi Liang, Shan Guorong, Bao Yongzhong, Zhao Qian, Xie Tao, Pan Pengju
State Key Laboratory of Chemical Engineering, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou, 310027, P. R. China.
Key Laboratory of Macromolecular Synthesis and Functionalization of Ministry of Education, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou, 310027, P. R. China.
Adv Mater. 2020 Jul;32(28):e2001693. doi: 10.1002/adma.202001693. Epub 2020 May 28.
Stimuli-responsive shape-transforming hydrogels have shown great potential toward various engineering applications including soft robotics and microfluidics. Despite significant progress in designing hydrogels with ever more sophisticated shape-morphing behaviors, an ultimate goal yet to be fulfilled is programmable reversible shape transformation. It is reported here that transient structural anisotropy can be programmed into copolymer hydrogels of N-isopropylacrylamide and stearyl acrylate. Structural anisotropy arises from the deformed hydrophobic domains of the stearyl groups after thermomechanical programming, which serves as a template for the reversible globule-to-coil transition of the poly(N-isopropylacrylamide) chains. The structural anisotropy is transient and can be erased upon cooling. This allows repeated programming for reversible shape transformation, an unknown feature for the current hydrogels. The programmable reversible transformation is expected to greatly extend the technical scope for hydrogel-based devices.
刺激响应性形状转变水凝胶在包括软机器人技术和微流体技术在内的各种工程应用中显示出巨大潜力。尽管在设计具有越来越复杂形状变形行为的水凝胶方面取得了重大进展，但一个尚未实现的最终目标是可编程的可逆形状转变。本文报道，瞬态结构各向异性可以被编程到N-异丙基丙烯酰胺和硬脂酰丙烯酸酯的共聚物水凝胶中。结构各向异性源于热机械编程后硬脂酰基团变形的疏水区域，它作为聚（N-异丙基丙烯酰胺）链可逆的球-线团转变的模板。这种结构各向异性是瞬态的，冷却后可以消除。这使得可逆形状转变能够进行重复编程，这是目前水凝胶所不具备的特性。可编程的可逆转变有望极大地扩展基于水凝胶的器件的技术范围。
