A novel amphoteric ion-exchange membrane (AIEM) was prepared through the pore-filling technique, for vanadium redox flow battery (VRBs) applications. Their physico-chemical properties including vanadium ion permeability and electrochemical properties were investigated as a function of cross-linking degrees. Vanadium ion permeability was effectively suppressed by the quaternary ammonium group-induced Donnan exclusion effect and was only 7.7% of that of Nafion117. Finally, open circuit voltage measurements showed that VRBs assembled with the AIEM maintained voltages >1.3 V for over 43 h, which was superior to the cation exchange membranes (CEMs), studied. In addition, the VRBs with AIEM-4 exhibited higher columbic efficiency (ca. 98%) and energy efficiency (ca. 89%) than those with CEMs. Therefore, it may be concluded that pore-filled AIEMs are more suitable for use in VRBs than pore-filled CEMs. This work provides a convenient method for preparing new types of IEMs for various applications.

In this study, cationic surfactants having two, three or four hydroxyl groups were synthesized by the condensation reaction of n octadecyl glycidyl ether and amine (methyl amine and dimethyl amine) fol lowed by the quaternization with dimethyl sulfate. The structure of a resulting product was determined by 1 H NMR and FT IR spectroscopies. Interfacial tensions measured as a function of time for n decane drops brought into contact with 1 wt. % surfactant solutions at 25°C indicated that the interfacial tension decreased over a period of about 10-15 min to an equilibrium value. The results of contact angle measurements indicate that C18 BADM surfactant having four hydroxyl groups is the best wetting agent among others studied. More over, the excellent adsorption capacity of C18 BADM system suggests that it can be used as a softening agent during a laundry process. The results of foam stability measurement were consistent with those of CMC and contact angle. The percentage of foam volume decrease was found to increase with the hydrophilicity of a sur factant.