Multiwalled Hollow Polyurethane and Graphene Oxide/Polyurethane Fibers in Janus Textiles for Thermal Management and Sensors

Multifunctional fibers and wearable textiles have enabled extensive and profound breakthroughs in personal thermal management. In addition to steady-state heat exchange, the initial unsteady-state period plays an integral part in the thermal comfort of humans . Herein, two structure-tunable fibers with inverse thermal properties under unsteady-state conditions were prepared via microfluidic spinning. The multiwalled hollow polyurethane fiber inspired by rabbit hair exhibits good thermal insulation, low thermal absorptivity, and a warm feeling of contact. While graphene oxide nanosheet/polyurethane hybrid fibers possess high thermal absorptivity and an intrinsic cold feeling of contact. As a proof of concept, these two fibers were knitted into different sides as 2D Janus textiles for reversible warm/cool feeling of contact under ambient temperature. Furthermore, compressible 3D smart textiles with a pressure sensor array is also prepared targeting smart insoles and bedsheets, where graphene-modified conductive fiber served as sensor units together with a warm/cool fiber for contact thermal comfort. Such bioinspired structure-tunable fibers focus on the unsteady-state thermal comfort and different contact surfaces can be chosen for summer and winter.