Cation hydration in hydrogelic polyacrylamide-phosphoric acid network : A study by Raman spectroscopy
Abstract The effects upon the structure and morphology of adding lithium, calcium and magnesium chlorides to a phosphoric acid/polyacrylamide 2:1 molar ratio proton conducting hydrogel are examined by observing the changes in the vibrational features of the polyacrylamide chain, in the phosphate group and in the interstitial water molecules as a function of the concentration and the cationic nature of the additive, at 295 K. On adding H 3 PO 4 to the polyacrylamide hydrogel matrix, the amide groups become more accessible and the polyacrylamide-phosphoric acid network behaves like structure-makers promoting a larger association in the ‘bulk’ liquid water molecules.