Hierarchical Porous Polymer Coatings Based on UV-Curing for Highly Efficient Passive All-Day Radiative Cooling

Passive radiative cooling provides a promising way to reduce energy consumption for cooling. However, it always requires stringent materials designs or manipulations, which are neither cost-effective nor widely adaptable. Here, we report a fast, inexpensive, and scalable UV-curing method to fabricate porous polymer coatings via photopolymerization-induced phase separation. This coating with hierarchical pore structure, has a superior long-wave infrared emittance of 0.98 and strong solar reflectance of 0.96, resulting in subambient temperature drops of ∼9.8 °C during the night and ∼5.7 °C under solar intensity of ∼960 W m–2 in the metropolitan area in summer. Moreover, the UV-cured coating is highly cross-linked and superhydrophobic without any treatment, showing excellent durability after long-term UV irradiation, thermal aging, or immersion in corrosive chemicals. The paint-like simplicity and remarkable weather resistance are vital for promoting practical applications of cooling coatings.