A unique copolymer stabilizer composed of poly(N-isopropylacrylamide) (PNIPAM) and poly(1-ethyl-3-vinylimidazolium bromide) (PEVImBr) was demonstrated to be used to stabilize multi-walled carbon nanotubes in aqueous solution to form �smart� dispersions. These two monomers were selected as PNIPAM is a well-known thermosensitive polymer with a low critical solution temperature (LCST) of 32�C, close to human body temperature, whilst PEVImBr is a poly(ionic liquid) that can disperse CNTs by strong polarization interactions and responds to ionic strength in solution. The copolymer stabilizer showed double stimuli-responsive behavior (in dependence of temperature and ionic strength) and allowed for accurate control of the transition (exfoliated?agglomerated) temperature of nanotubes over a wide temperature range. In spite of its effective dispersion strength, the copolymer was easily synthesized in one step via free radical copolymerization of N-isopropylacrylamide and 1-ethyl-3-vinylimidazolium bromide. In our following research, we improved this stabilizer system by employing a homopolymer rather than a copolymer poly(ionic liquid) poly(tetrabutylphosphonium 4-styrenesulfonate), which was found to show tunable lower critical solution temperatures in aqueous solution, depending on concentration and ionic strength. As this polymer also exhibits a very high stabilizing power for carbon nanostructures, one can readily synthesize environment-sensitive graphene dispersion.

Double stimuli-responsive poly(ionic liquid) stabilizers for carbon nanostructures

245th National Meeting (2013)

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