Ligament-Inspired Tough and Anisotropic Fibrous Gel Belt with Programed Shape Deformations via Dynamic Stretching

Nature provides perpetual inspiration for exploring anisotropic materials to implement complex functions and motions like biological organisms. In particular, fibrous hydrogel-based anisotropic aggregates have attracted tremendous interest as fantastic materials for development into artificial ligaments or muscles. Such aggregates combine the structural anisotropy and macroscopic flexibility of fiber materials, with the intelligence, softness, and wetness of hydrogel materials. However, controlled fabrication of such hydrogels with aligned microstructures, even in a macroscopic level, remains a challenge. Here, a facile and general strategy was proposed to develop ligament-inspired multistructural (mono/bilayer) gel belts via dynamic stretching of multistrand pregels, accompanied by the simultaneous assembly of hydrogel fibers. The resultant gel belts evolved into anisotropic and aligned micro- and macrostructures, exhibiting high elastic moduli (0.01-23.5 MPa) and unique anisotropic swelling behaviors. Through further physical and chemical structure design, bioinspired multiple fibrous gel-based actuators were developed to achieve anisotropic, relatively fast (within 60 s), and delicate macroscopic shape deformations. This work provides a great platform for the design and construction of next-generation soft materials for biomimetic tissues.