Arrested Phase Separation Enables Optimal Light Management toward High-Performance Passive Radiative Cooling Film

Daytime passive radiative cooling has emerged as an energy-saving cooling technique. However, market penetration of current daytime passive radiative cooling-related membranes is still miniscule due to deficiencies in scalability, recyclability, and robustness. This work successfully addresses these issues by concurrently imparting the following features in a designed polymeric cooler: (1) cost-effective and recyclable raw materials that highlight the sustainability; (2) scalable yet exquisite structure-engineering strategy to afford superb light scattering performance; (3) malleable under facile conditions to fit complex surface conformably. Specifically, our cooling membrane is solely composed of a mass chemical, polyvinyl butyral, which forms a supramolecular network with the polymer–air interface as light scattering sites and −C–O–C– bonds as infrared emitters. The structure of the polyvinyl butyral membrane is exquisitely organized via kinetical arrest of network-forming phase separation. The spatial size, contrast, and distribution of phase domains can be finely manipulated via tuning the composition routes and depth of phase separation. The optimized membrane demonstrates all-day and all-climate cooling with a 7.3 °C subambient cooling and 62 W/m2 cooling power. In addition to this superb cooling performance, this membrane uniquely affords a collective of multiple features, such as cost effectiveness, recyclability, and hydrophobicity.