Fabrication of self-replenishing hydrophobic surfaces and self-cleaning coating based on self-crosslinkable PDMS-g-WPU emulsion

Abstract

Nowadays, many self-healing strategies used in recovery of surface functionality have drawn much attention to improving durability of materials. In this study, a self-replenishing hydrophobic surface was constructed at low temperature with crosslinkable PDMS-g-WPU emulsions. The PDMS-g-WPU emulsion was prepared by step-growth addition polymerization. And the influence of grafted PDMS content on surface recovery was discussed. AFM, XRD and DMA results all demonstrated the biphasic microphase separation of PDMS-g-WPU films. When the mass proportion of PDMS to WPU was 25 wt%, the copolymer film reserved the largest number of PDMS microspheres, and optimal surface replenishing ability was obtained. Meanwhile, the copolymer films showed stable hydrophobicity against abrasion by sandpaper, UV irradiation and soaking in acid solution, as well as exhibited significant anti-icing performance. Additionally, a self-cleaning coating precursor was easily fabricated by spraying the mixture of PDMS-g-WPU emulsion (WPS25)/BaSO4/PTFE particles. This hydrophobic precursor could turn into a self-cleaning coating through abrasion based on the self-replenishment of WPS25. After 100 abrasion cycles under 4.4 kPa, the coating maintained WCA of 142.5° and sliding angle (SA) of 31.8°. Therefore, this graft copolymer could be applied in complicated work conditions and satisfied the need for practical applications.