Key Laboratory of Colloid and Interface Chemistry, Shandong University, Ministry of Education, Jinan, Shandong, 250100, Peoples' Republic of China.
Phys Chem Chem Phys. 2011 Jan 28;13(4):1332-7. doi: 10.1039/c0cp00342e. Epub 2010 Nov 23.
The micellization of the ionic liquid N-alkyl-N-methylpyrrolidinium bromide (C(n)MPB, n = 12, 14 and 16) in aqueous solutions was investigated by surface tension measurements, electrical conductivity and static luminescence quenching. The effectiveness of the surface tension reduction (Π(cmc)), maximum surface excess concentration (Γ(max)) and the minimum area (A(min)) occupied per surfactant molecule at the air/water interface can be obtained from the surface tension measurements at 25 °C. The critical micelle concentration (cmc) at different temperatures and a series of thermodynamic parameters (ΔG, ΔH and ΔS) of micellization were evaluated from electrical conductivity measurements in the temperature range of 25-45 °C. The thermodynamic parameters show that the micelle formation is entropy-driven at low temperature and enthalpy-driven at high temperature. Furthermore, the micelle aggregation number (N(agg)) of C(n)MPB was calculated according to the Turro-Yekta method through static luminescence quenching and found that N(agg) (49, 55, and 59) increased with the hydrophobic chain length of C(n)MPB.
采用表面张力法、电导法和静态荧光猝灭法研究了离子液体 N-烷基-N-甲基吡咯烷溴化物（C(n)MPB，n = 12、14 和 16）在水溶液中的胶束化。在 25°C 下通过表面张力测量可获得降低表面张力的有效性（Π(cmc)）、最大表面过剩浓度（Γ(max)）和每个表面活性剂分子在气/水界面上的最小面积（A(min)）。通过电导法在 25-45°C 的温度范围内测定了不同温度下的临界胶束浓度（cmc）和一系列胶束化热力学参数（ΔG、ΔH 和 ΔS）。热力学参数表明，胶束的形成在低温下是熵驱动的，在高温下是焓驱动的。此外，根据 Turro-Yekta 方法通过静态荧光猝灭法计算了 C(n)MPB 的胶束聚集数（N(agg)），发现 N(agg)（49、55 和 59）随 C(n)MPB 的疏水链长而增加。
