Facile fabrication of a low adhesion, stable and superhydrophobic filter paper modified with ZnO microclusters

A robust superhydrophobic ZnO coating on a filter paper substrate was successfully prepared for the first time by using a successive deposition process and chemical modification. The surface morphology, chemical composition, wetting property, mechanical stability, chemical stability and durability of the filter papers were examined. The as-prepared papers exhibited an improved rough surface topography compared with the uncoated paper due to the uniform ZnO microclusters decorated on the reticular fibers. More importantly, it was found that the wettability of papers was dependent on the surface roughness, which was governed by the number of ZnO microcluster deposition cycles. After the chemical modification with stearic acid, the resulting paper with 4 cycles presented the optimized superhydrophobicity with a water contact angle (WCA) of 158°, a slide angle (SA) of 3°, a low adhesion and good bounce performance. The chemical resistance of the superhydrophobic paper to corrosive liquids was studied. Moreover, the superhydrophobicity of paper was not affected after the water drops impact test or it was kept for 6 months, indicating its high impact resistance and long-term stability. The excellent superhydrophobicity of paper can be attributed to the synergistic effect of the suitable micro/nanoscale hierarchical roughness and the low surface energy modification.