Surface and thermodynamic properties of diquaternary bola‐form amphiphiles containing an aromatic spacer

Abstract

Abstract A series of diquaternary ammonium bromides having phenyl groups with different (CH 2 /N + ) ratios were synthesized. The critical micelle concentration of each amphiphile was determined using equilibrium surface tension and equivalent conductance data. Air/water interfacial parameters were measured at 20, 35, and 50°C. The surface tension isotherms of the different diquaternary amphiphiles showed two region of discontinuity corresponding to two critical micelle concentrations. The first was related to the spherical nature of the micelles, whereas the second was related to the multiple loops of the lamellar aggregates. The prepared compounds were evaluated as a new class of diquaternary ammonium compounds for future application in protection of steel fabrics against aggressive media (2 N HCl). The results showed that the prepared amphiphiles offered good corrosion inhibition efficiency. Also, increasing the hydrophobic chain length and/or concentration increased their efficiency.