摘要
界面电位是影响分子界面行为的一个重要因素。Zeta电位测试技术常用于界面电位的测定~([1])。二次谐波光谱技术,作为一种具有分子层次敏感性的界面探测方法,已经被广泛用于研究界面上分子的动力学行为~([2,3])。我们使用二次谐波技术和动态光散射Zeta电位测试技术,研究了水中氢氧根离子、阴离子表面活性剂十二烷基硫酸钠以及盐的浓度变化对十六烷-水界面电位的影响。Zeta电位测量实验结果表明,随着盐浓度的增加,部分界面具有反常的电位极大值。由Zeta电位计算得到的界面双电层中的电荷密度以及由SHG实验结果推算出的Stern层的厚度,理解了离子效应对界面电位变化的具体影响。此研究结果从分子层次上为进一步丰富和完善界面双电层理论提供了实验和理论支持。
Surface potential is one of the most important factors that influence the interface behaviour of molecules. Zeta potential measurement is generally used to test the surface potential. With its unique interface selectivity, Second Harmonic Generation(SHG) has also been widely used to study the dynamic behaviour of molecules at interfaces. In this work, we report the electric charge at the hexadecane-water interface at varied concentrations of hydroxide ions, sodium dodecyl sulphate and NaCl with SHG and zeta potential measurements. The results showed an anomalous maximum in zeta potential curve in some cases. The charge density calculated from the zeta potential measurements and the thickness of the stern layer obtained from SHG were used to interpret the influence of ionic strength on surface potential. This work provides information for more understanding on the electric double layer theory.
引文
[1]Marinova,K.G.;Alargova,R.G.;Ivanov,I.B.;Borwankar,R.P.Langmuir 1996,12(8):2045-2051.
[2]Wei Wu,Hui Fang,Wei Gan.J.Phys.Chem.C,2016,120(12):6515–6523.
[3]Elsa C.Y.Yan,Yan Liu,and Kenneth B.Eisenthal*.J.Phys.Chem.B,1998,102(33):6331-6336.