Superhydrophobic paper with superior stability against deformations and humidity

Abstract Superhydrophobic coatings on paper were achieved by means of incorporating micro-nano hierarchical topography, where the water droplet was repelled and rested in a spherical shape. A silica sol, which was prepared using tetraethylorthosilicate (TEOS) as precursor and trimethylethoxysilane (TMES) as co-precursor, was poured on the paper to form a superhydrophobic surface. The coating was fluorine-free, environmentally friend, and could be easily fabricated on different kinds of papers. Besides, the transmittance of prepared coating reached up to 92% in visible light range, and the words on treated paper showed a good visualization. Moreover, the treated paper showed superior mechanical durability against 100 times of deformation, remarkable stability towards both the acidic and basic solutions. The treated paper could withstand 70 cycles of water condensation test (from 60 °C, 90% relative humidity to 10 °C) without losing superhydrophobicity, suggesting a long-term protection for paper.