Chapter 2 - Nanocomposite membrane materials

Abstract

The selection of polymers and nanomaterials is equally important to fabricate nanocomposite membranes with desired physico-chemical properties and gas separation performances. The physico-chemical properties of the polymers in terms of thermal stability, ageing behaviour, solubility and diffusivity should be thoroughly evaluated. Glassy polymers have been known as an important class of polymeric membranes for gas separation owing to their excellent thermal, chemical and mechanical stability as well as very promising gas permeability and selectivity. Recently, polymers of intrinsic microporosity and thermally rearranged polymer have also gained popularity in nanocomposite membrane fabrication due to their exceptional gas separation properties. Other classes of polymeric materials that have been commonly used as the continuous phase in nanocomposite membranes include rubbery polymers such as poly(ethylene oxide) and polyurethane, facilitated transport polymers and poly(ionic liquid). The use of nanofillers of different properties within a single unit of nanocomposite membrane is an interesting approach towards improved separation performance. Different factors have equally important influences on the molecular sieving process and separation of species. These factors include the pore geometry and connectivity, pore size, pore density, as well as the interactions between the penetrants and the pore surface chemistry. Some of the widely investigated nanofillers for gas separation nanocomposite membranes are zeolite, metal organic framework and carbon-based nanomaterials.