Water-Based Superhydrophobic Coatings for Nonwoven and Cellulosic Substrates

The intense commercial demand for efficient fluid management (e.g., water barriers) has resulted in a recent proliferation of methods intended to impart liquid repellency to various substrates. Many such methods involve wet-based processing of hydrophobic polymers and thus rely heavily on organic solvents whose properties pose environmental challenges when scaled up from the laboratory bench. The current study presents a one-step, environmentally safe (>97 wt % water), room-temperature, low-cost, polymer-based technique that imparts superhydrophobicity to commercially relevant porous substrates. The method features aqueous dispersions of a commercially available fluoroacrylic copolymer and hydrophilic bentonite nanoclay and uses spray casting to apply coatings which are subsequently dried in open air to form thin conformal films. Wettability measurements demonstrate that the coating formulation imparts considerable resistance to water penetration in polymeric nonwoven and cellulosic substrates. In addition to the benign environmental impact of the aqueous formulation, all ingredients are commercially available, thus opening many technological opportunities in this area.