Hybrid passive cooling composites based on silane‐bridged titanium dioxide and low‐density polyethylene

Abstract Passive cooling materials represent an effective and environmentally friendly strategy for achieving energy efficiency. The passive cooling performance can be achieved by shielding partial solar irradiance and transmitting infrared radiation emitted by the human body or surroundings. One solution is to utilize the Mie scattering theory of nanoparticles (NPs) dispersed in polymers to adjust the spectral transmissivity. However, the performance of passive cooling materials is often limited by the agglomeration of NPs in the polymer matrix. In this study, spherical titanium dioxide (TiO 2 ) NPs with a diameter of 350 nm were surface‐modified by different concentrations and durations of the silane coupling agent 3‐ (trimethoxy silyl) propyl methacrylate (KH‐570). Then, the 2 wt% surface‐modified TiO 2 NPs were extruded with low‐density polyethylene (LDPE) to obtain well‐dispersed passive cooling composites. The optimal passive cooling performance was achieved using TiO 2 NPs treated with 20 wt% KH‐570 for 8 h. The fabricated composites exhibited an average solar irradiation shielding rate of 58.0%, an average atmospheric window transmissivity of 97.1%, and a cooling performance of 10.0°C under direct solar exposure. This study presented an economical approach for achieving passive cooling with potential applications in building envelopes, industrial facilities, and personal thermal management systems. Highlights TiO 2 NPs were modified by KH‐570 under varying concentrations and durations. Polymer composites hybridized with modified TiO 2 NPs and LDPE were fabricated. The composites exhibited excellent solar irradiation shielding performance. The composites achieved optimal transmittance across atmospheric windows.