Stretch‐Induced Conductivity Enhancement in Highly Conductive and Tough Hydrogels

• Published in: Advanced materials (Weinheim) 2024-06, Vol.36 (25), p.e2313845-n/a
• Main Authors: Wang, Xiaowei, Zheng, Sijie, Xiong, Jiaofeng, Liu, Ziyang, Li, Qingning, Li, Weizheng, Yan, Feng
• Format: Article
• Language: English
• Subjects: conductive hydrogel; Crack tips; Crosslinking; Deformation effects; Elastomers; Electrical resistivity; Fatigue failure; Fatigue strength; Formability; Hydrogels; liquid metal; Liquid metals; Mechanical properties; Nanowires; Polyvinyl alcohol; recyclable; Silver; Stress concentration; stretchable electronics; stretch‐induced orientation; Tensile strain
• ISSN: 0935-9648; 1521-4095; 1521-4095
• DOI: 10.1002/adma.202313845

The resistance of gels and elastomers increases significantly with tensile strain, which reduces conductive stability and restricts their use in stable and reliable electronics. Here, highly conductive tough hydrogels composed of silver nanowires (AgNWs), liquid metal (LM), and poly(vinyl alcohol) (PVA) are fabricated. The stretch‐induced orientations of AgNWs, deformable LM, and PVA nanocrystalline create conductive pathways, enhancing the mechanical properties of the hydrogels, including increased ultimate fracture stress (13‐33 MPa), strain (3000–5300%), and toughness (390.9–765.1 MJ m−3). Notably, the electrical conductivity of the hydrogels is significantly improved from 4.05 × 10−3 to 24 S m−1 when stretched to 4200% strain, representing a 6000‐fold enhancement. The incorporation of PVA nanocrystalline, deformable LM, and AgNWs effectively mitigates stress concentration at the crack tip, thereby conferring crack propagation insensitivity and fatigue resistance to the hydrogels. Moreover, the hydrogels are designed with a reversible crosslinking network, allowing for water‐induced recycling. Highly conductive and tough hydrogels composed of liquid metal (LM), silver nanowires (AgNWs), and poly(vinyl alcohol) (PVA) are constructed. The stretch‐induced orientations of AgNWs, deformable LM, and PVA nanocrystalline form conductive pathways and enhance the mechanical properties of hydrogels, including ultimate fracture stress, strain, toughness, and dramatically enhance the electrical conductivity (from 4.05 × 10−3 to 24 S m−1 at 4200% strain).