The composition of the adsorbed film and the excess Gibbs energy of adsorption ĝH,E were evaluated from thermodynamic analysis of surface tensions for the 1-decyl-3-methylimidazoulium bromide (C 10mimBr)-tetraethylene glycol monooctyl ether (C8E 4) and 1-decyl-3-methyl-imidazolium tetrafluorobrorate (C 10mimBF4)-C8E4 systems, where the counter anion of imidazolium salts is different from each other. The higher miscibility of two components compared to an ideal mixing and thus negative ĝH,E were observed in the former, which comes from the ion-dipole interaction between imidazolium cation and the oxyethylene group of C8E4. On the other hand, the lower miscibility and thus positive ĝH,E were observed for the latter. Such differences were attributed to that BF4 - forms two hydrogen bonds and has stronger affinity with the cationic head group of C10mim + than Br-. This results in that the ion-dipole interaction between C8E4 and C10mim+ cation is diminished in the C10mimBF4-C8E 4 system.
All Science Journal Classification (ASJC) codes
- Physical and Theoretical Chemistry
- Polymers and Plastics
- Colloid and Surface Chemistry
- Materials Chemistry