Recent developments in stimuli-responsive poly(ionic liquid)s

Abstract

The current challenge is to focus on the fundamental understanding of ion-containing polymers. Poly(ionic liquid)s (PILs) belong to an important subclass of ionic polyelectrolyte with broad range of structural and functional properties. This review outlines the different kinds of stimuli-responsive PILs those are recently developed, specifically highlighting our own work and their materialistic applications. A brief introduction is also been provided to describe the advancement of PILs over their monomeric ionic liquids’ (ILs) moiety and their smart responsive behaviour towards different chemical, physical and biochemical stimuli such as pH, redox, CO2, temperature, light, enzyme etc. The thermoresponsive PILs with lower critical solution temperature (LCST)- or upper critical solution temperature (UCST)-type phase transition behaviours are discussed in a generalized way. The pH-responsive PILs also prove themselves as a potent candidate for potential applications in the biomedical area including therapy, drug delivery, diagnostics, etc. and the synthetic developments of those are also described here briefly. The rise of atmospheric CO2 level is now a matter of worldwide concern. Thus, in particular, CO2 responsive materials have attracted much attention and in this regards, PILs are much familiar and are found to be sorptive in nature both physically and chemically. Therefore, it is indeed important to describe the role and potential applications of PILs those are responsive to CO2. Polymerized ionic liquids (PILs), those are responsive to other different stimuli such as photo, redox etc., are also described in this review.