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

Abstract

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 structureengineering 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/m 2 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.

Chaotropic Salt Dispersion Enables Room-Temperature Synthesis of High-Purity Polyvinyl Butyral

“…4−7 The growth in the automotive glass market is anticipated to propel the demand for laminated glass over the forecast period. Recent advancements have unveiled pioneering uses of PVB and its analogues in diverse fields, including a substrate for soft lithography, 8 a refractive layer for optical devices, 9 pervaporation membranes, 10 biodegradable packaging, 11,12 radiative cooling membranes, 13,14 and even biomedical engineering, exemplified by optical imaging, 15 skin patches, 16 and keratoprostheses. 16 The demands of these applications necessitate PVB products characterized by robust mechanical properties, strong glass adhesion, favorable solubility, and heightened thermal stability.…”

“…The molecular structure and purity of PVB play pivotal roles in defining its attributes. The anticipated molecular structure of PVB receives collective affirmation through the utilization of 1 H and 13 C nuclear magnetic resonance (NMR) spectroscopy (as illustrated in Figures S3 and S4). Furthermore, 1 H NMR analysis indicates that the AD value for SCN-B reaches an impressive range of 72−75% within 2.5 h (Figure 2b), signifying the consumption of over 90% of the initial n-butanal feedstock.…”

“…Poly­(vinyl butyral) (PVB), composed of vinyl butyral, vinyl alcohol, and vinyl acetate segments (Figure a), finds a broad spectrum of applications encompassing robust bonding, optical clarity, and adhesive properties in laminated glass for automotive and solar cell, − as well as its role as a coalescing agent in tape casting and 3D printing inks. − The growth in the automotive glass market is anticipated to propel the demand for laminated glass over the forecast period. Recent advancements have unveiled pioneering uses of PVB and its analogues in diverse fields, including a substrate for soft lithography, a refractive layer for optical devices, pervaporation membranes, biodegradable packaging, , radiative cooling membranes, , and even biomedical engineering, exemplified by optical imaging, skin patches, and keratoprostheses . The demands of these applications necessitate PVB products characterized by robust mechanical properties, strong glass adhesion, favorable solubility, and heightened thermal stability.…”

Harmonizing Sunlight and Architecture for Argema-Inspired Nanocellulose Aerogel Radiative Coolers via Energy Tailoring Strategy

“…To date, a large amount of radiative cooling materials have been developed, including photonic structure, 3 hybrid metamaterials, 4 organic coating, 5 microporous polymer film, 1,6 plastic textiles, 7,8 and white wood. 9 However, most of the existing passive daytime coolers are produced from nonenvironmentally friendly raw materials, which will have a negative impact on the environment.…”

BaSO4-Epoxy Resin Composite Film for Efficient Daytime Radiative Cooling

“…In addition, the complex crystal structure and proper bonding strength of BaSO 4 allow for the presence of a large number of central optical phonon modes in the infrared active region in the Reststrahen band, which results in a higher emissivity in the sky window compared with other inorganic particles . Conventional BaSO 4 nanopowders are easy to agglomerate, which may heavily affect the radiative cooling effect and the mechanical properties of inorganic composites. ,− Therefore, the dispersibility of nanoparticles is crucial to improve the performance of composites. Nanodispersions are nanoparticles that can be uniformly dispersed in liquid media and remain stable over time.…”