Use of Mineral Pigments in Fabrication of Superhydrophobically Engineered Cellulosic Paper

Superhydrophobic materials have a lot of interesting potential applications. The self-cleaning property is a unique feature. Rendering the water-loving cellulosic paper superhydrophobic can open the door for value-added applications. Superhydrophobic paper is a fairly new area, and only very limited scientific publications are available in the literature. Among these publications, the topics on the use of mineral pigments in fabrication of superhydrophobic structures account for a large proportion. During the fabrication process, mineral pigments, e.g., silica, precipitated calcium carbonate, and clay, generally need to be hydrophobized, either directly or indirectly. Mineral pigments can be applied to cellulosic paper by surface treatment or wet-end filling, and good dispersabilities of these pigments are always highly demanded. A key mechanistic point is that by tunable particle packing or fabrication, mineral pigments may exhibit surface-roughening effects, which are critical for superhydrophobicity development. The roughening of a hydrophobic surface helps to enhance hydrophobicity. Possible concepts such as nano-structuring or controllable surface patterning of mineral pigments may help to improve superhydrophobicity. Environmental friendliness will also guide the scientific/technical development in this area.