Development and preliminary testing of self-cleaning cool materials for building and urban applications

This study presents preliminary results on self-cleaning cool materials prototypes based either on photocatalytic, hydrophilic and hydrophobic technological solutions. Ad-hoc nanocomposite formulations have been developed on a lab scale for coatings suitable for building application, either in factory or on site. Prototypes are made of an embossed aluminum tape layer that grants the high reflectance of a cool material, then covered with proprietary nanocomposite self-cleaning thin films, developed on a lab scale. A set of samples has been prepared and characterized to determine relevant chemical-physical properties, like the water contact angle. WCA that results of 128 degrees for the super-hydrophobic one and <10 degrees for superhydrophilic one, Spectrophotometric measurements of solar reflectance are carried out before exposing prototypes to the outdoor environment for a monitoring campaign. The initial reflectance of the reference aluminum sample exhibited 81% initial solar reflectance that decreased to 80% after 3 month exposure. The newly developed samples scored an initial reflectance between 39 and 84%, after three months it was in the 83-84% range after washing. The scaling-up of the technology has been projected with preliminary tests on spray for polymeric layers and on a pre-industrial sputtering equipment also for inorganic products.