对羟基苯甲酸丁酯在蓖麻油-水界面上自组装及其重构动力学研究

Self-Assembling Dynamics of p-Butyl Hydroxybenzoate at Castor Oil-Water Interface by Cyclic Voltemmetry

以循环伏安法研究了对羟基苯甲酸丁酯在蓖麻油-水界面上自组装膜生长动力学,在自组装初期苯环以卧式定向按指数生长规律形成Langmuir自组装膜,成膜速率常数为0.0216min-1,单分子扩散系数为1.14×10-6cm2/s。自组装后期,苯环的卧式定向转化为立式定向,遵从S形玻兹曼函数,转化速率常数为k=0.0143min-1。自组装膜在支持电解质中以指数函数形式进一步重构成为完整、稳定的有序膜,重构速率常数为k=0.0319(±0.0011)min-1。自组装膜修饰电极在较高扫速下符合理想电容器模型,而在较低扫速下受离子扩散影响。自组装膜修饰较大程度地提高了电极的双电层电容。

In the present paper, the self-assembling dynamics castor oil/water interface was studied by cyclic voltammetry. of At p-ethylhydroxybenzoate at the beginning, p-butyl hydroxybenzoate forms an horizontally oriented self assembly membrane （SAM） according to Langmuir＇s formula with rate constant of 0. 0216min^-1 and molecular diffusion coefficient of 1. 14×10^-6cm^2/s. After 110min,the horizontal oriented SAM transfers into vertical oriented SAM follows the sigmoidal Boltzman function with rate constant of k= 0. 0143min^-1. At lower monomer concentration （% 1.0 mmol/L）, the SAM is mainly horizontal oriented,but at higher concentration （ 1.0 mmol/L）, the vertical oriented SAM is directly electrolyte solution, and forms a stable and perfect formed. The SAM rearranges in 0. 5mol/L KCl SAM with rearrangement rate constant of k=0. 0319 （±0. 0011 ）min^-1. The SAM modified electrode follows the ideal capacitor model at higher scan rate （〉 100mV/s）, but influenced by ion diffusion at lower scan rate （% 100mV/s）. The modification of the SAM greatly increases the double layer capacitor.