Crack-Resistant and Self-Healable Passive Radiative Cooling Silicone Compounds.

Crack damage and expansion are prevalent issues in outdoor materials, which absorb or transmit sunlight to damaged areas, substantially impairing the functionality of passive radiative cooling systems. Herein, a silicone/dielectric radiative cooling compound is introduced that is both self-healing and crack-resistant, developed through the synthesis of a dynamic and crack-resistant polymer/dielectric hydrogen bond network. This network incorporates boron nitride dielectrics, which serve as sunlight scatterers and hydrogen bond acceptors, with customized silicone polymer featuring high atmospheric window emissive chain segments and UV-vis-NIR transparent hydrogen bond moieties. When cracks form, the polymer's chain mobility allows the hydrogen bond moieties in boron nitride and silicone to re-associate, realizing self-healing of cracks from micrometers to millimeters wide and restoring cooling performance to ≈100%. The combination of rigid boron nitride and sacrificial hydrogen bonds in polymer also enhances the materials' fracture energy to 865%, effectively preventing further crack propagation under stress through autonomous crack blunting and deflection. These remarkable characteristics make this radiative cooling compound highly suited for increasingly complex, dynamic, and prolonged outdoor application environments.