Homogeneous polyelectrolyte complex (PEC) hydrogels made from chitosan and carboxymethylcellulose were prepared in the LiOH/KOH/urea aqueous system through a freeze–thawing method. Following the treatments of sequential chemical and physical cross-linking, the resulting hydrogels with supertough mechanical strength can operate as fast response actuators under electrical stimulus in salt aqueous solutions. The electromechanical behaviors of the hydrogels are strongly dependent on experimental parameters such as electric voltage, solvent constituents, pH, and ionic strength. It is proposed that the electromechanical deformation of hydrogel originates from a dynamic osmotic equilibrium effect taking place at the interface between the hydrogel and the surrounding medium, which is induced by the migration of ions throughout the gel network. In addition, programmable 3D shape transformations were obtained by using the PEC hydrogel with designed 2D geometric patterns. Moreover, the bending actuation behavior of the PEC hydrogel can propel an adjacent object to move forward. These hydrogels are expected to be used as underwater actuators for soft robotics and other smart biomimetic systems.

中文翻译：

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天然衍生多糖的电响应均相聚电解质复合水凝胶

由壳聚糖和羧甲基纤维素制成的均相聚电解质复合物（PEC）水凝胶是通过冻融法在LiOH / KOH /尿素水体系中制备的。经过顺序的化学和物理交联处理，具有超强机械强度的所得水凝胶可以在盐水溶液中的电刺激下作为快速响应的促发剂起作用。水凝胶的机电行为在很大程度上取决于实验参数，例如电压，溶剂成分，pH和离子强度。提出水凝胶的机电变形源自在水凝胶与周围介质之间的界面处发生的动态渗透平衡效应，这是由于离子在整个凝胶网络中的迁移所引起的。此外，通过使用具有设计的2D几何图案的PEC水凝胶可获得可编程的3D形状转换。而且，PEC水凝胶的弯曲致动行为可以推动相邻的物体向前移动。这些水凝胶有望用作软机器人和其他智能仿生系统的水下执行器。