Develop self adhesive to stick on moist and icy substrates

Normal acrylic-based adhesives that stick to dry surfaces, do not stick to surfaces with a water film. The water decreases the Hamaker constant, which indicates the strength of the Van der Waals forces, by a factor 10. The time needed to squeeze out the water by applying pressure to a label on top of a wet surface, is too long for normal applications. Approaches to remove, use and penetrate the moisture layer are proposed. This work focuses on proposals for water removal and this case is analyzed theoretically and tested experimentally. Pores are needed to transport the water away from the gap between the substrate and the adhesive layer. We show experimentally that adhesives with pores (50 µm diameter, 1 mm spacing) have a larger pull-off force on wet surfaces after applying pressure than adhesives without pores. Theoretical calculations for a 20µm thick adhesive layer of 645 mm2 surface area with 800 holes of 10µm diameter, show that the maximum volume of water retainable in the capillaries is 1.5 .10 -12 m3. This value is 500 times less than the volume of water squeezed out when the layer is reduced to 1µm. Therefore pores need to be made through both the adhesive and film layer where the water can evaporate or an absorbance layer is needed. Alternative strategies proposed to improve adhesion performance on moist icy surfaces include addition of polysaccharides, (poly)electrolytes, nanofibres, functionalized superhydrophobic and superhydrophilic patterns of the adhesive layer