Superhydrophobic paper could be prepared by spraying an
ethanol suspension containing commercially available SiO2
nanoparticles at room temperature and under atmospheric
pressure. The hydrophobicity of the coatings could be
controlled by two factors: the aggregation state of the SiO2
nanoparticles, which depends on the type of alcohol in the
suspension, and the SiO2 particle size. The visibility of
characters on the paper was maintained after coating with
SiO2 nanoparticles. The advantage of our method is the
simplicity of the process; this study clearly indicates that costly
instrumentation, extreme reaction conditions, and specialized
nanomaterials are not necessary to prepare superhydrophobic
and transparent films on paper.