Cellular Core/Sheath Filaments with Thermoresponsive Vacuum Cavities for Prolonged Passive Temperature-Adaptive Thermoregulation.

Acting as the interface between the human body and its environment, clothing is indispensable in human thermoregulation and even survival under extreme environmental conditions. Development of clothing textiles with prolonged passive temperature-adaptive thermoregulation without external energy consumption is much needed for protection from thermal stress and energy saving, but very challenging. Here, a temperature-adaptive thermoregulation filament (TATF) consisting of thermoresponsive vacuum cavities formed by the temperature-responsive volume change of the material confined in the cellular cores of the filament is proposed. Using a droplet-based microfluidic system, the cellular core/sheath filament using octadecane (OD) as a temperature-responsive volume-changing material to form droplet cellular cores within the thermoplastic polyurethane (TPU) sheath is fabricated. It is found that the fabric made of TATF has a remarkable temperature adaptive thermal conductivity, which increases by 83% as the mean fabric temperature increases from 20 °C to 35 °C, due to the volume change of vacuum cavities in the cellular cores of the filament in response to temperature. TATF fabrics have no problem associated with undesirable appearance changes or leakage of encapsulated molten materials as some existing thermoregulatory textiles do, and can therefore have wide applications in functional clothing for prolonged passive personal thermal management.