A Novel BST@TPU Membrane with Superior UV Durability for Highly Efficient Daytime Radiative Cooling

Passive radiative cooling technologies play an integral role in advancing sustainable development. While the potential of polymer-based radiative cooling materials is increasingly recognized, they often degrade under prolonged ultraviolet (UV) radiation exposure, which undermines both their mechanical and radiative cooling performance. To address this challenge, a coaxial electrospinning method to prepare a BST@TPU membrane, with a core layer of strontium barium titanate nanorods (BST NRs) and a shell layer of thermoplastic polyurethane (TPU) is employed. Capitalizing on the UV absorption and free radical adsorption properties of BST NRs, the UV stability of the TPU membrane is significantly increased. Additionally, the inclusion of high refractive index BST NRs compensates for the decrease in reflectivity caused by their UV absorption. After 216 h of continuous 0.7 kW m⁻² UV irradiation, the BST@TPU membrane, which initially exhibits a reflectance of 97.2%, demonstrated a modest decline to 92.1%. Its net radiative cooling power maintains 85.78 W m⁻² from the initial of 125.21 W m⁻², extending the useful lifetime of the TPU membrane threefold. This innovation extends promise for enhancing the efficiency and durability of radiative cooling materials, contributing to sustainable cooling solutions across various applications.