FTIR spectroscopic study of the complex formation between H+ and DMSO in Nafion

Abstract Nafion membranes plasticized with dimethyl sulfoxide (DMSO) have been examined at room temperature using the vacuum ATR - FTIR spectroscopic technique in the range 50–4000 cm − 1 . The amount of the plasticizer corresponds to the molecular ratio n  = DMSO/H +  = 1.2, 2.3, 4.8, 7.0, 9.7 and 13.3. The medium intensity band with two maxima at 780 and 853 cm − 1 have been assigned to the ν (SO) stretching vibrations of the H + (DMSO) 2 complex. The possible reason of ν (SO) splitting is symmetry decrease of hydrogen bond under the influence of the anion group SO 3 − electric field. Whereas the mutual association of free DMSO molecules in Nafion leads to appearance of weak band at 86 cm − 1 assigned to the dipole-dipole interactions.