Self-healing Stretchable Composite Conductors

As electronic devices are increasingly employed in various industrial fields, the use of conventional conductors in novel electronics is typically unsuitable for achieving both ultimate mechanical and electrical performance. Some studies have suggested stretchable conductors created through metal patterning (e.g. serpentine, origami) or blended elastic materials, but damaged stretchable conductors exhibit dramatic performance deterioration and shorten the lifespan of electronics. The development of self-healing stretchable composite conductors (SSCCs) provides feasibility and opportunities for developing next-generation electronic devices such as flexible mobile devices, stretchable conductive fibers, long-term implantable electronics, high-performance wearable electronics, actuator systems, and sensory systems. The design of a self-healing stretchable matrix is based on the introduction of various intrinsic self-healing pathways (e.g. dynamic covalent bonding (DCB), Host-Guest interactions, ion-dipole interactions, liquid metal (LM) reformation, coordination bonding, and hydrogen bonding) to stretchable composite polymer networks (e.g. polysiloxane-based thermoplastics). In addition, previous studies related to conductive composite fabrication have suggested optimal approaches for imparting conductivity to self-healing stretchable composites. The well-known fabrication protocols for conductive composites can be divided into two categories: (i) elastomer-based conductors prepared by embedding metal or conjugated polymers; and (ii) gel-type conductors fabricated by a sol-gel transition, including conductive liquids such as water and ionic liquids (ILs). Each elastomer- and gel-based composite has different purposes depending on several factors, such as their mechanical strength, interaction with conductive materials, backbone polarity, moldability, and type of conductivity (e.g. ionic or electrical). In this chapter, self-healing stretchable composite conductors (SSCCs) are classified into different types based on their self-healing mechanisms, and composite conductor-based self-healing stretchable devices are introduced.