Local water management in cotton linter papers with silica-based coatings

Abstract

Paper with its mechanical strength as well as due to its microfluidic properties has emerged asan interesting sustainable material for future hightech applications. Examples include paper-based sensors and actuators, paper-based construction materials and paper-based membranes. These examples have in common that a precise control of the water distribution inside the paper sheet during fluid water imbibition, water vapor adsorption, or drying affects the fluidic properties of the paper, which are crucial for its performance. Here silica-based coatings are applied to control the water distribution in the paper sheet during imbibition, adsorption and drying. By using dense silica coatings, the fibers are shielded from water penetration which limits the water distribution into the fiber–fiber voids. Whereas with a mesoporous silica coating, mesopores can be inserted into the paper, providing an additional space for water imbibition and adsorption. Water location upon imbibition, adsorption and drying were investigated using small angle x-ray scattering and gravimetric water vapor adsorption. Thereby, water distribution upon imbibition and adsorption depends on the type of silica coating. In addition, the drying mechanism and water distribution during drying is as well determined by the silica-based coating. The obtained results allow to deduce design criteria for local water management in paper sheets.