Patterned Electrode Assisted One‐Step Fabrication of Biomimetic Morphing Hydrogels with Sophisticated Anisotropic Structures

• Published in: Advanced science 2021-12, Vol.8 (24), p.e2102353-n/a
• Main Authors: Zhu, Qing Li, Dai, Chen Fei, Wagner, Daniel, Khoruzhenko, Olena, Hong, Wei, Breu, Josef, Zheng, Qiang, Wu, Zi Liang
• Format: Article
• Language: English
• Subjects: Anisotropy; Biomimetic Materials - classification; biomimetic structures; Biomimetics - methods; Cellulose; Deformation; Electric fields; electrical orientations; Electrodes; Glass substrates; Hydrogels; Hydrogels - chemistry; Magnetic fields; Mechanical properties; morphing materials; Nanoparticles; Polymerization; Robots; soft actuators
• ISSN: 2198-3844; 2198-3844
• DOI: 10.1002/advs.202102353

Anisotropic structures are ubiquitous in nature, affording fascinating morphing behaviors. Biomimetic morphing materials can be developed by spatially controlling the orientations of molecules or nanofillers that produce anisotropic responses and internal stresses under external stimuli. However, it remains a serious challenge to fabricate materials with sophisticated anisotropic architectures. Here, a facile strategy to fabricate morphing hydrogels with elaborately ordered structures of nanosheets, which are oriented under distributed electric field and immobilized by polymerization to form a poly(N‐isopropylacrylamide) matrix, is proposed. Diverse sophisticated anisotropic structures are obtained by engineering the electric field through the patterns and relative locations of the electrodes. Upon heating, the monolithic hydrogels with through‐thickness and/or in‐plane gradients in orientation of the nanosheets deform into various three‐dimensional configurations. After incorporating gold nanoparticles, the hydrogels become photoresponsive and capable of programmable motions, for example, dynamic twisting and flipping under spatiotemporal stimuli. Such a strategy of using patterned electrodes to generate distributed electric field should be applicable to systems of liquid crystals or charged particles/molecules to direct orientation or electrophoresis and form functional structures. The biomimetically architectured hydrogels would be ideal materials to develop artificial muscles, soft actuators/robots, and biomedical devices with versatile applications. Biomimetic morphing hydrogels with sophisticated anisotropic structures are developed by using a distributed electric field to orient the nanosheets that are then immobilized in a thermoresponsive matrix. The electric field can be facilely tuned by structured electrodes with tailored patterns and positions. The resultant hydrogels with specific gradient of orientations exhibit programmed deformations and motions upon spatiotemporal stimulation.