Superhydrophobic Coatings on Cellulose-Based Materials: Fabrication, Properties, and Applications

Wettability of a solid surface by a liquid plays an important role in several phenomena and applications, for example in adhesion, printing, and self-cleaning. In particular, wetting of rough surfaces has attracted great scientific interest in recent decades. Superhydrophobic surfaces, which possess extraordinary water repelling properties due to their low surface energy and specific nanometer- and micrometer-scale roughness, are of particular interest due to the great variety of potential applications ranging from self-cleaning surfaces to microfluidic devices. In recent years, the potential of superhydrophobic cellulose-based materials in the function of smart devices and functional clothing has been recognized, and in the past few years cellulose-based materials have established themselves among the most frequently used substrates for superhydrophobic coatings. In this Review, over 40 different approaches to fabricate superhydrophobic coatings on cellulose-based materials are discussed in detail. In addition to the anti-wetting properties of the coatings, particular attention is paid to coating durability and other incorporated functionalities such as gas permeability, transparency, UV-shielding, photoactivity, and self-healing properties. Potential applications for the superhydrophobic cellulose-based materials range from water- and stain-repellent, self-cleaning and breathable clothing to cheap and disposable lab-on-a-chip devices made from renewable sources with reduced material consumption.