MXene-Anchored PAN Fibrous Membranes with Excellent Thermal Insulation Capacity for Personal Thermal Management

Personal thermal management (PTM), which greatly contributes to the regulation of thermal transfer based on a "human skin–fibrous membrane material–external environment" microclimate system, has been an attractive strategy to achieve personal thermal comfort. As the "second skin" of the human body, a fibrous material has been regarded as the "bridge" for thermal transfer between the human body and the ambient environment. Accordingly, PTM based on fibrous materials is the most directive and effective way to realize personal comfort even without extra energy consumption. Herein, we propose a highly effective thermal insulation strategy to achieve PTM by fabricating polyacrylonitrile (PAN) fibrous membranes via electrospinning and incorporating MXene multilayered nanoflakes during the in situ self-polymerization of dopamine. Besides, the fibrous structure of as-prepared membranes, i.e., fibers that are randomly stacked and horizontally and vertically oriented, are taken into consideration to unveil the relationship between fiber structure and personal thermal management capacity. Taking advantage of both the low human body infrared (HBIR) emissivity of intrinsic electrospun PAN fibers and the excellent photothermal conversion capacity of MXene, as well as the randomly stacked fibers that can enhance multiple reflection and absorption of radiation within the membranes by increasing the interaction paths between radiation and the material, a MXene@PDA–PAN fibrous membrane with randomly stacked fibers shows minimal HBIR emissivity (32.7%) and ultralow thermal conductivity (27.44 mW·m–1·K–1), leading to a temperature increase of approximately 17.7 °C compared to the traditional cotton fabric under solar irradiation in an outdoor environment. Such work contributes to keeping a constant temperature and relative warmth in cold outdoor environments and offers insights into the facile design and fabrication of fibrous materials for enhancing personal thermal management. It also establishes a promising strategy not only for maintaining personal comfort and improving work efficiency but also for ensuring the special functionalities of state-of-the-art wearable and multifunctional fabrics.