Scalable thermochromic superhydrophobic collagen fiber-based wearable materials for all-weather self-adaptive radiative cooling and solar heating

As traditional biomaterials for wearables, collagen fibers (CFs)-based products are widely used in daily life due to their exceptional performance. However, developing CFs-derived products that exhibit seasonal self-adaptive temperature regulation to satisfy the thermal comfort for humans and prolong their service life remains a significant challenge in practical applications. Herein, the smart temperature-adaptive superhydrophobic radiative cooling CFs (STSRC-CFs) were created through a nanoengineering design strategy by a simple and scalable layer-by-layer spraying method. The STSRC-CFs inherit the outstanding properties of natural CFs and maintain high tensile strength (18.2 MPa), air permeability (38.2 mL/cm2∙h), and superhydrophobicity (CA of 161.1°, SA of 2.0°). Moreover, STSRC-CFs possessed a thermal emittance of 0.94, while the solar reflectance could be dynamically modulated in response to the ambient temperature change with a solar reflectance of 0.91 at high temperatures and 0.81 at low temperatures. The synergic effect enables STSRC-CFs to autonomously manage radiative cooling and solar heating, thereby achieving intelligent energy-saving temperature regulation for winter warming and summer cooling. Notably, the superhydrophobic self-cleaning effect of STSRC-CFs prevents from contamination, ensuring sustained spectral modulation and intelligent temperature regulation. Serving as a proof-of-concept for intelligent self-adaptive passive temperature regulation, the STSRC-CFs introduced in this study lay the groundwork for the development of advanced temperature-adaptive radiative cooling and solar heating functional materials.