Herein, thermochromic superhydrophobic coatings (TSCs) with different colors are prepared, and their surface wettabilities and optical properties are studied. The TSC coating maintains its surface superhydrophobicity even after a series of mechanical damage (sandpaper abrasion, gravel impact, and knife scratching), chemical corrosion, ultraviolet aging, and environmental temperature changes. Contaminants on the surface of the coating sre easily washed by water droplets. The TSC has a reversible color function with a critical discoloration temperature (T c ) approximately in the range 28-31 C. In winter, the ambient temperature (T a ) is lower than T c , and the TSC is dark and absorbs more solar energy. Although in summer, T a > T a , the TSC is light and reflects more solar energy. The sunlight exposure test shows that the surface temperature of the thermochromic pigment/polydimethylsiloxane (TP/PDMS) coating in winter is only 0.9 C lower than that of the carbon black/PDMS (CB/PDMS) coating, whereas in summer, the surface temperature of the TP/PDMS coating is only 6.2 C higher than that of TiO 2 /PDMS coating. Energy consumption simulation results show that the TP/PDMS coating decreases the total annual energy consumption in North China by 13.74% compared with the traditional white cooling coating.

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In this work, magnesium oxychloride cement (MOC) was used to realize the resource use of foundry dust (FD). Portland cement (PC)-based superhydrophobic coating was prepared on the surface of FD/MOC composite to improve the water resistance of the composite. First, the FD/MOC composites with different contents of FD were prepared. The phase structure of the composite was analyzed using X-ray diffraction (XRD). The microstructure of the cross-section and surface of the composite was observed using field emission scanning electron microscope (FE-SEM). The mechanical properties of the FD/MOC composites with different FD contents at different ages were tested and analyzed. Secondly, the superhydrophobic coating was prepared on the surface of MOC composite using silane/siloxane aqueous emulsion as the hydrophobic modifier, PC as the matrix and water as the solvent. The microstructure and chemical composition of the PC-based superhydrophobic coating were tested and analyzed. The results show that FD can significantly improve the early strength of the FD/MOC composite. The 28-day compressive strength of the FD/MOC composite decreases with increasing FD content. When the FD content is 30%, the 28-day compressive strength of the FD/MOC composite is as high as 75.68 MPa. Superhydrophobic coating can effectively improve the water resistance of the FD/MOC composite. The softening coefficient of the FD/MOC composite without superhydrophobic coating is less than 0.26, while that of the composite modified by superhydrophobic coating is greater than 0.81.

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