Intermolecular Interactions Between Methanol/Water Molecules and Nafion™ Membrane: An Infrared Spectroscopy Study

Abstract

The intermolecular interactions between methanol/water and Nafion™ membranes have been investigated using IR spectroscopy. The evolution of IR spectra of the Nafion™ membranes, immersed in various concentrations of methanol solution depends strongly on the methanol concentration. The O–H bending vibration modes at 1,636, 1,660 and 1,672 cm–1 associated with the hydrogen bonding of (H3O+…SO3–) as well as (CH3OH2+…SO3–), and at 1,702, 1,717 and 1,711–1,736 cm–1 associated with the hydrogen bonding of (CF2…H–O–CH3), (CF2…H–OH), (CF2…+H3O) and (CF2…H–OSO2–) were observed. The vibration mode of (CF2…H–O) was found to be appearing obviously at 3,821–3,900 cm–1 when the Nafion™ membrane was immersed in the methanol solution with concentration higher than 6 M. On the other hand, the wavenumber of the O–H stretching peak increases with an increase in the methanol concentration. Results of IR spectra revealed that the methanol molecules show better capability to penetrate into the hydrophobic domain of the Nafion™ membrane than water. The intermolecular interaction between the hydrophobic domains of Nafion™ and methanol molecules becomes more observable at a higher methanol concentration.

Poly(styrene sulfonic acid)/poly(vinyl alcohol) copolymers with semi-interpenetrating networks as highly sulfonated proton-conducting membranes

“…1 × 10 −7 cm 2 S −1 . The proton conductivity increased with an increase in water uptake and IEC, which results from the increase in the -SO 3 samples contained a sufficient amount of PSSA to produce a densely tangled IPN structure, effectively preventing MeOH permeability, thereby generating the best selectivity. The membrane without a semi-IPN structure (i.e.…”

“…We attribute the peak at 1037 cm −1 to a combination of symmetric vibration of the SO 3 H groups [4] and C-H bending of the benzene rings. Unfortunately, asymmetric vibrations representing SO 3 − group asymmetry, expected at ca. 1164 cm −1 were obscured by the intense C-O-C stretching vibration and could not be located precisely.…”

“…Nafion, which features a poly(tetrafluoroethylene) backbone presenting perfluorinated pendent chains terminated by sulfonic acid units, offers exceptional: chemical, thermal, and mechanical stability, together with high proton conductivity. Nevertheless, the high cost of Nafion's cell components, its instability at high temperatures, and its high methanol (MeOH) permeability hinder its widespread applicability [1][2][3]. To reduce the permeability (cross-over) of the fuel (MeOH) in DMFCs, from the anode side of the membrane to the cathode side, the solid polymer electrolyte membrane in a DMFC must act as a barrier [4].…”

Electricity generating capacity and performance deterioration of a microbial fuel cell fed with beer brewery wastewater

“…4B was centered at 1638 cm À1 and was attributed to the bending vibration of the eOH group bonded with the ÀSO 3 À group (30,31). The intensity of this band increased after use of the membrane in MFC, which indicated the interactions of beer brewery wastewater molecules with the hydrophilic domains of the cation exchange membrane (31,32). The broad peaks observed were centered at 1538 cm À1 for the membrane used in MFC and were assigned to the bending vibrations of CeH (28) (Fig.…”

Investigation of solvent–solute interactions and film properties of perfluorinated sulfonic acid (PFSA) ionomers

“…the solvent viscosity, molar volume, donor properties and the solvent uptake by the membrane. The intermolecular interactions between methanol/water solution mixture and Nafion ® membranes have been investigated using FTIR spectroscopy [6]. Results of FTIR spectra revealed that the methanol molecules show better capability than water molecules to penetrate into the hydrophobic domain of Nafion ® membrane.…”