US Patent 11851871 Multifunctional system for passive heat and water management

In an embodiment, a multifunctional material system is provided and can include a variable-permeability layer, a desiccant containing layer, and a vapor-permeable supporting layer. The variable-permeability layer can have a vapor permeability that increases with increasing relative humidity. The desiccant containing layer can be adjacent the variable-permeability layer. The vapor-permeable supporting layer can be positioned adjacent at least one of the variable-permeability layer and the desiccant containing layer. Water moves in a first direction from the variable-permeability layer to the desiccant layer when relative humidity is greater adjacent the variable-permeability layer than the desiccant layer. Water moves a second, opposing direction, from the desiccant containing layer to the variable-permeability layer when the relative humidity is greater adjacent the desiccant containing layer than the variable-permeability layer. The rate of water motion in the first direction is greater than the second direction when the humidity gradient is reversed.