Application of superhydrophobic sol gel on canvas

•Superhydrophobic sol gel (SHSG) was applied to canvas.•WCA of two bilayers PTFE/SHSG-coated canvas were 153.3°±3.1°.•SHSG provided the roughness and hydrophobic bonds needed for superhydrophobicity.•PTFE provided CF2 groups nearest to the surface to resist the water impact.•A PTFE/SHSG-coated canvas was stronger than a PTFE-coated canvas in weathering test. In this study, a superhydrophobic sol gel (SHSG) was used to promote self-cleaning ability of canvas. Four kinds of coating methods were studied and water impact test was used to assess the quality of the coating. The scraper method rendered a relatively flat surface; and water contact angles (WCAs) of two bilayers polytetrafluoroethylene (PTFE)/SHSG-coated canvas were 153.3°±3.1° and 141.7°±3.3° before and after water impact of 2h, respectively. SEM, energy dispersive x-ray spectrometry (EDX), and FTIR were applied to characterize the PTFE/SHSG coating. Although SHSG was dropped on top of the PTFE film during sample preparation, the analysis of EDX and FTIR indicated that the chains of PTFE extended upward and SHSG moved downward during the heat treatment with preheat. The combination of SHSG with PTFE promoted not only hydrophobicity but also the strength and weatherability of the canvas. The tensile strength of a PTFE/SHSG-coated canvas was always superior to a PTFE-coated canvas during accelerated weathering test. After accelerated weathering test of 300h, the two bilayers PTFE/SHSG-coated canvas had a tensile strength of 237kg, static WCA of 143.7°±2.1°, a contact angle hysteresis of 8°, and a sliding angle of 4°, which represented an outstanding self-cleaning ability.