A PDMS modified polyurethane/Ag composite coating with super-hydrophobicity and low infrared emissivity

Polydimethylsiloxane (PDMS) modified polyurethane (PU)/Ag composite coating with super-hydrophobicity and low infrared emissivity was prepared via glass rod scraping method using nano-SiO2, PDMS modified PU, and flaky Ag powder as micro-nano structural modifier, adhesive, and functional pigment, respectively. The effects of particle size of flaky Ag powder, Ag powder addition, and the ratio of Ag powder and nano-SiO2 on the coating performance have been discussed. The results show that when the particle size of flaky Ag powder was 10 mu m, and the content of Ag powder in the coating was 50 wt%, the coating had a dense surface structure and lowest infrared emissivity. The modification of coating with appropriate amount of nano-SiO2 led to clear mastoid micro-nano rough structures on the coating surface, so that the coating could achieve super-hydrophobic properties. When the ratio of Ag powder and nano-SiO2 in the coating was 6:4, the WCA of the coating reached 151 degrees, the sliding angle reached 9 degrees, and the coating had outstanding self-cleaning performance. At the same time, the super-hydrophobic PDMS modified PU/Ag composite coating had relatively low emissivity (0.709) and extremely low glossiness (4.0) properties.