Novel superhydrophobic NIR reflective coatings based on Montmorillonite/SiO2 composites for Energy-saving building

In recent years, cool building materials have received increasing attentions due to their superior energy-saving efficiencies. In this work, novel self-cleaning cool coatings based on fluorocarbon resin-montmorillonite (MMT)/SiO2 composites were prepared for energy-saving buildings. The intercalation modification of MMT improved the dispersion stability of MMT in organic solvent. Surface modification of MMT and SiO2 particles by fluoroalkyl silane (FAS) produced hydrophobic particles. Fluorocarbon resin was used as a binder. With the assistance of the micro/nano structure of montmorillonite/SiO2 composites and low surface energy of FAS and fluorocarbon resin, superhydrophobic state of the MMT/SiO2 composite coatings can be achieved. The maximum contact angle of the MMT/SiO2 composite coatings was as high as 163.5°. The superhydrophobic composite coatings exhibited superior self-cleaning property and good mechanical durability. Furthermore, the NIR solar reflectance of the superhydrophobic montmorillonite/SiO2 composite coatings ranged from 0.77 to 0.85. The composite coatings reduced the heat box’s inside temperature of by 5.9℃. Therefore, the integration of high NIR reflectance property and superior self-cleaning property makes montmorillonite/SiO2 composite coatings good candidates as self-cleaning cool roof coatings for energy-saving buildings.