Stable and Wearable Multifunctional Nanofiber-Based Foaming Nonwoven for High-Performance Thermal Insulation in Complex Environments

Abstract

Conventional thermal insulating fibrous materials are often limited by their bulkiness, insufficient insulation, and lack of functional versatility, which restrict their ability to deliver adequate wearing comfort and reliable warmth retention in complex environments, thereby impeding broader practical application. Herein, a multifunctional foamed composite nanofiber nonwoven (FCNN) material, derived from thermal expansion microspheres (TEMs), is developed through a synchronous electrospinning/electrospraying technique. This material integrates high wearing comfort, washability, excellent thermal insulation performance, and robust mechanical stability into a single structure. The FCNN material is composed of a superhydrophobic thermoplastic polyurethane (TPU)–polyacrylonitrile (PAN) nanofiber matrix with an interlaced fiber architecture, in which TEMs and MXene nanosheets are uniformly embedded. The obtained FCNN material exhibits an ultralow thermal conductivity of 0.014 W·m–1·K–1 and low density of approximately 0.013 g·cm–3. Its superhydrophobic feature effectively repels water penetration, preserving structural integrity and performance stability under humid conditions. Moreover, the FCNN shows favorable air permeability (21–23 mm/s) and moisture permeability with water vapor transmission (WVT) of ∼20 kg/m2·d, demonstrating the superior wear comfort. The incorporation of MXene imparts additional functionalities, including strong antibacterial efficiency (>99% against both Escherichia coli and Staphylococcus aureus) and effective electromagnetic absorption performance with a minimum reflection loss (RLmin) of −34.25 dB and effective absorption bandwidth (EAB) of 4.12 GHz in X-band. Notably, this FCNN material exhibits outstanding durability, maintaining its structural coherence and functional performances even after repeated washing, exposure to strong acids and alkalis, and multiple cycles of mechanical deformation/compression.