Abstract
Silica nanoparticles (7 nm) were dispersed in solutions of a silane/siloxane mixture. The dispersions were applied, by brush, on four types of paper: (i) modern, unprinted (blank) paper, (ii) modern paper where a text was printed using a common laser jet printer, (iii) a handmade paper sheet detached from an old book, and (iv) Japanese tissue paper. It is shown that superhydrophobicity and water repellency were achieved on the surface of the deposited films, when high particle concentrations were used (≥1% w/v), corresponding to high static (θS ≈ 162°) and low tilt (θt < 3°) contact angles. To interpret these results, scanning electron microscopy (SEM) was employed to observe the surface morphologies of the siloxane‐nanoparticle films. Static contact angles, measured on surfaces that were prepared from dilute dispersions (particle concentration <1% w/v), increased with particle concentration and attained a maximum value (162°) which corresponds to superhydrophobicity. Increasing further the particle concentration did not have any effect on θS. Colourimetric measurements showed that the superhydrophobic films had negligible effects on the aesthetic appearance of the treated papers. Furthermore, it is shown that the superhydrophobic character of the siloxane‐nanoparticle films was stable over a wide range of pH.
Highlights
Superhydrophobic surfaces have attracted considerable attention in the last two decades because of their various potential applications relevant to water repellency, self-cleaning, friction reduction, and antifouling [1]
We describe an extremely simple method to induce superhydrophobicity on paper: silica (SiO2) nanoparticles (7 nm) are dispersed in a silane/siloxane solution, and the dispersions are used to coat four types of paper by brush
We report that superhydrophobicity and water repellency were achieved for siloxane-particle films deposited by spray
Summary
Superhydrophobic surfaces have attracted considerable attention in the last two decades because of their various potential applications relevant to water repellency, self-cleaning, friction reduction, and antifouling [1]. The inherent hydrophilic nature of cellulose poses obvious limitations in the use of paper, when hydrophobicity is highly demanded. Water/moisture resistance of paper is important for the packaging industry [4]. Superhydrophobic, water repellent coatings can provide enhanced protection against water and moisture. Another potential application of water repellent films on paper is related to the preservation of documents and books, which is aided by the unique antisticking and self-cleaning property. Developing strategies to control the interaction of paper with water is important in the development of inexpensive microfluidic paper-based devices used for different purposes
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