Mechanoresponsive Polymerized Liquid Metal Networks

• Published in: Advanced materials (Weinheim) 2019-10, Vol.31 (40), p.e1903864-n/a
• Main Authors: Thrasher, Carl J., Farrell, Zachary J., Morris, Nicholas J., Willey, Carson L., Tabor, Christopher E.
• Format: Article
• Language: English
• Subjects: Casting; Circuits; Elongation; Gallium base alloys; Liquid metals; Materials science; Networks; particle–polymer networks; Polymerization; Skin; stimuli‐responsive; stretchable conductors; stretchable heaters; Structural hierarchy; Wearable technology
• ISSN: 0935-9648; 1521-4095
• DOI: 10.1002/adma.201903864

Room‐temperature liquid metals, such as nontoxic gallium alloys, show enormous promise to revolutionize stretchable electronics for next‐generation soft robotic, e‐skin, and wearable technologies. Core–shell particles of liquid metal with surface‐bound acrylate ligands are synthesized and polymerized together to create cross‐linked particle networks comprising >99.9% liquid metal by weight. When stretched, particles within these polymerized liquid metal networks (Poly‐LMNs) rupture and release their liquid metal payload, resulting in a rapid 108‐fold increase in the network's conductivity. These networks autonomously form hierarchical structures that mitigate the deleterious effects of strain on electronic performance and give rise to emergent properties. Notable characteristics include nearly constant resistances over large strains, electronic strain memory, and increasing volumetric conductivity with strain to over 20 000 S cm−1 at >700% elongation. Furthermore, these Poly‐LMNs exhibit exceptional performance as stretchable heaters, retaining 96% of their areal power across relevant physiological strains. Remarkable electromechanical properties, responsive behaviors, and facile processing make Poly‐LMNs ideal for stretchable power delivery, sensing, and circuitry. Core–shell liquid metal particles functionalized with acrylate ligands are polymerized to create cross‐linked particle networks. When these polymerized liquid metal networks are stretched, their constituent particles rupture and the network transitions from insulating to conductive. These networks autonomously form hierarchical structures that help maintain stable electrical behavior under high strains and exhibit excellent performance as stretchable conductors and heaters.