Fabrication of superhydrophobic P(VDF-HFP)/SiO2 composite film for stable radiative cooling

Superhydrophobic SiO2–Glass Bubbles Composite Coating for Stable and Highly Efficient Daytime Radiative Cooling

“…The equilibrium value was reached gradually as the content of GB increases, SiO 2 -GB4.0 had a high reflectivity and mid-infrared emissivity at an addition level of 4.0 g. When too many GB were added, SiO 2 was unable to cover the surface of the GB, resulting in a loss of the micro-/nanohierarchical structure leading to reduced optical properties. In addition, according to Mie scattering, the micro-pores formed by the SiO 2 distributed on the GB were distributed within 0.5–2 μm (Figure d,e) and could scatter sunlight effectively . SiO 2 had an intrinsic Fröhlich resonance in the 9–12 μm band, and GB particles between 4 and 16 μm enhanced absorption in the mid-infrared region .…”

“…In addition, according to Mie scattering, the micro-pores formed by the SiO 2 distributed on the GB were distributed within 0.5−2 μm (Figure 2d,e) and could scatter sunlight effectively. 47 SiO 2 had an intrinsic Froḧlich resonance in the 9−12 μm band, 33 and GB particles between 4 and 16 μm enhanced absorption in the mid-infrared region. 48 Therefore, the Si−O bond had a strong selective emission in the atmospheric window and was able to radiate heat into the atmospheric window to achieve a cooling effect.…”

“…In comparison, the average temperature drop for commercial superhydrophobic silica over the same period was only 1.6 °C, with a maximum temperature difference of 3.8 °C, much less than SDRC aluminum (7.2, 8.2 °C). Due to the lower midinfrared emissivity of aluminum, 47 the average temperature rise of the aluminum sheet ΔT = 0.9 °C was greater than the air temperature under PE shielding under the same conditions, and the maximum temperature difference could reach 2.8 °C (Figure 8b).…”

Geopolymer‐based sub‐ambient daytime radiative cooling coating

“…Organic polymeric coatings have been then studied to promote the wider applications of SDRC technology due to their ease in manufacturing, low cost, good spectral tunability and versatile functionality (e.g., through the use of various functional fillers) 12–14 . It is especially noteworthy that many polymers are characterized with functional groups that can facilitate sufficient infrared radiation in the atmospheric window and high transparency for the solar spectrum 15 .…”

“…4,[6][7][8][9][10][11][12] Organic polymeric coatings have been then studied to promote the wider applications of SDRC technology due to their ease in manufacturing, low cost, good spectral tunability and versatile functionality (e.g., through the use of various functional fillers). [12][13][14] It is especially noteworthy that many polymers are characterized with functional groups that can facilitate sufficient infrared radiation in the atmospheric window and high transparency for the solar spectrum. 15 Various strategies have been adopted to enhance the cooling performance of the polymeric SDRC coatings [16][17][18][19][20][21] : (1) to choose organic polymer matrices with molecular bonds including C O, C F, C Cl, etc., to enable high emittance in the infrared atmospheric window; (2) to further enhance the infrared radiation through phonon resonance of SiO 2 microparticles; (3) to improve the solar reflectance through introducing functional fillers (TiO 2 , Al 2 O 3 , CaCO 3 , BaSO 4 , ZnO, etc.)…”