Polymeric membranes are membranes that take the form of polymeric interphases, which can selectively transfer certain chemical species over others. There are several mechanisms that could be deployed in their functioning. Knudsen diffusion and solution diffusion are prominent mechanisms. Polymeric membranes are of particular importance in gas separation applications. Polymer membrane filtration processes are increasingly employed for water desalination and purification, being inherently less energy intensive than distillation and more reliable than flocculation methods. Some industrial applications include oxygen-nitrogen separation, removal of organics and natural gas enrichment.