Application of stimuli responsive polymers for sustainable ion exchange chromatography

•SRP polymers have a huge potential for sustainable bioseparation.•Several studies on thermoresponsive stationary phases.•Studies mainly on analytical separation.•More research needed for industrial scale separation.

Ion exchange processes are widely used in the food, bioprocessing and related industries for the isolation of proteins and other ionic species. Traditional ion exchange resins require salts, acids or bases for releasing adsorbed molecules creating a strong saline waste stream with negative environmental and economic impact. Stimuli responsive polymers (SRPs) with ion exchange functional groups can be used to selectively capture and release charged molecules from a complex mixture using physical stimuli to trigger conformational transitions in the polymer. The structural change of the polymers in response to a stimulus may lead to reduced ligand–target molecule interaction resulting in the release of the captured molecule without the use of chemical reagents, thereby reducing the environmental burden associated with ion exchange processes. The use of temperature responsive polymers has already been demonstrated for such applications at analytical scale. However, little progress has been made to extend these discoveries to the development of materials and methods amenable to industrial scale processing. So far, other SRPs such as, electric, magnetic and light responsive polymers remain largely unexplored for such application. This article discusses the potential of temperature responsive and other SRPs for developing sustainable ion exchange processes. It also highlights the material science and engineering challenges that need to be overcome to bring such processes to industrial application.