Wetting enhanced by water adsorption in hygroscopic plantlike materials

The wetting properties of a liquid along cell-walls of plant-like systems or in porous hydrogels change from poor to good wetting when the walls are saturated with bound water, which then allows liquid displacement. As a consequence, the dynamics of capillary imbibition of free water in hygroscopic systems may be strongly damped (by several orders of magnitude) although water can freely climb over significant heights. This process might contribute to the regulation of water absorption in unsaturated wood and could be explored to design porous materials with tunable liquid adsorption.