Stretchable and electrically conductive polyurethane- silver/graphene composite fibers prepared by wet-spinning process

In recent years, much research has been conducted on wearable electronic devices based on human-friendly factors, and fibers having stretchability and electrical conductivity are required as a component technology of fiber-based wearable electronics. Here we demonstrate stretchable and electrically conductive polyurethane (PU)-silver/graphene composite fibers prepared by wet-spinning process, in which silver nanoparticles (AgNPs) and graphene nanoplatelets (GNPs) are added as conductive fillers. Although the aspect ratio of AgNPs is relatively small compared to nanowires and nanotubes, high conductivity and stretchability have been observed in PU-AgNPs composites, which depends on the volume fraction of AgNPs in the composites. In addition, the conductivity was improved by curing treatment and addition of a small amount of GNPs, and a high conductivity of 82,874 S m ⁻¹ was achieved with a ∼150% strain. Conventional yarn-like conductive threads consisting of six strands of PU-AgNPs/GNPs composite fibers showed a relatively low resistance change up to 30% strain and operated as stretchable conductor up to 100% stretch in a circuit. Thus, it is expected that the PU-AgNPs/GNPs composite fibers can be applicable to human costume, industrial robots, and wearable electronics such as adaptive sensor for body movement measurement or medical monitoring, and biological integration systems for rehabilitation or injury prevention.