A process for forming room temperature water soluble polymer coatings on porous substrates by forming a solution of a room temperature water soluble polymer, one or more crosslinkers, a solvent for the room temperature water soluble polymer such as water and optionally one or more porogens, or functional agents, stirring the mixture until all the components are dissolved, adding the solution to a porous structure such as a non-woven fabric or a porous membrane and drying the solution on to the substrate as a coating before subjecting the coating to crosslinking. Alternatively, the coating may be partially crosslinked before drying the solution. Porous structures having a room temperature water soluble polymer coating and being capable of convective flow through the pores of the structure and diffusive flow through the coating can be formed.