The physicochemical properties of free-standing cross-linked poly(N-isopropylacrylamide) (pNIPAAM) gels, generated in the presence of the Ionic Liquids (ILs), 1-ethyl-3-methylimidazolium [C2mIm]+ salts of ethylsulfate [EtSO4]-, dicyanamide [DCA]- , bis(trifluoromethylsulfonyl)imide [NTf2]-, and Trihexyltetradecylphosphonium dycanamide ([P6,6,6,14][DCA]) are described. The Lower Critical Solution Temperature (LCST) of the resulting ionogel was found to vary between 24 – 31 oC. The behaviour of swelling is found to be as high as 31.55% (± 0.47, n = 3) from the initial dehydrated state, while 28.04% (± 0.42, n = 3) shrinking from the hydrated swollen state is observed. For ionogels based on the [DCA]- anion an unexpected complete loss of the shrinking behaviour occurs, attributed to water interactions with the nitrile group of the [DCA]- anion. Scanning Electron Microscopy also reveals distinct morphological changes, for example [C2mim][EtSO4] displays a highly porous, nodule type morphology, efficiently pre-disposed for water uptake.
Item Type:
Article (Published)
Refereed:
Yes
Additional Information:
We acknowledge support under the Marie Curie IRSESMASK project (PIRSES-GA-2010-269302), Science Foundation Ireland grant (07/CE/I1147), Marie Curie Actions re-integration grant PIRG07-GA-2010-268365 (for K.J.F) and the Irish Research Council. D.R.M. is grateful to the Australian Research Council for his Federation and Australian Laureate
Fellowships. We also acknowledge the contribution of Dr. Gary Annat for performing viscosity measurements.