Development of <scp>TPU</scp> Composite Micro‐Nano Fibers Based on Coaxial Electrospinning and Research on Their Thermal Regulation and Humidity Response

ABSTRACT Coaxial electrospun microfibers, distinguished by their unique structural attributes and remarkable adaptability, have attracted considerable interest in the domain of smart materials. The aim of this study is to prepare composite microfibers (Nfc‐s) with polyethylene glycol (PEG) as the core layer and thermoplastic polyurethane (TPU) as the shell layer by coaxial electrostatic spinning, to systematically investigate the role of the core solvent on the modulation of the functional properties of the microfibers, and to evaluate the potential for their application as smart materials. Coaxial electrospun microfibers (Nfc‐s) with a PEG core and TPU shell show tailored properties based on the core solvent. Three types were synthesized: TpP@w (H 2 O), TpP@t (THF), and TpP@d (DMF). Water‐based Nfc‐s (TpP@w) had high elongation at break; THF‐based fibers (TpP@t) displayed a significantly higher elastic modulus; DMF‐based ones (TpP@d) exhibited exceptional thermal hysteresis. All Nfc‐s exhibited improved hydrophilicity relative to pure TPU, with TpP@t and TpP@d demonstrating superior performance, evidenced by contact angles of 55.45° and 56.08°, respectively. Moreover, the T‐TpP@t (TPU/TPU‐PEG@THF) composite nanofibers attained a maximum bending angle of 12° and a recovery rate of 63.6% at 60% humidity. These results highlight the novel characteristics of Nfc‐s as a functional material with considerable potential for applications in clothing, home textiles, and healthcare.