اندازه گیری کشش سطحی مایعات یونی بر پایه آمونیوم

in this thesis protic and aprotic ammonium-based ionic liquids were synthesized and their surface tensions were measured in the range of 298-373k. the protics are alkyl ammonium-based ils with the carboxylate (formate, acetate, propionate) anion and aprotics are quaternary ammonium-based ils with bis(trifluoromethylsulfonyl)imide anion. capillary rise method was used for surface tension measurements. a special capillary apparatus which allows surface tension measurement under water free atmosphere was used. thus, the measurement of surface tension was performed at liquid/vapor equilibrium. the surface tension of quaternary ammonium-based ils decreases as the alkyl chain length increases. also surface energy and surface entropy increases with increasing alkyl chain length. in alkyl ammonium-based ils, as the anion gets larger, the surface tension and surface energy decreases while the surface entropy increases. for alkyl ammonium-based ils, the critical temperature that determined using the measured surface tension decreases with alkyl chain length of the anion. in the same way the critical temperature of the quaternary ammonium-based decreases with the alkyl chain length of the cation.