3种燕尾形双子表面活性剂的合成及其表面活性

Synthesis and surface activities of three swallow-tail gemini surfactants

设计合成了3种基于五苯基苯骨架结构的苝二酰亚胺衍生物n-PDI（n=2,3,4）双子表面活性剂,利用红外光谱仪、核磁共振氢谱仪、热重分析仪,对所合成的3种目标产物结构进行表征与确认,它们的分解温度均在200℃以上。研究了3种双子表面活性剂表面活性参数和热力学参数,结果表明双子表面活性剂分子在水溶液中形成胶束和在气-液界面处的吸附过程是自发的;且双子表面活性剂分子形成胶束的过程易于进行;随温度的升高ΔGmic、ΔHmic、ΔSmic均减小,表明ΔHmic对ΔGmic的贡献有增大趋势,ΔSmic对ΔGmic的贡献有下降趋势,即胶束化过程为熵驱动力在减小而焓驱动力在增大的过程。由SEM测试表明双子表面活性剂能有效吸附在锌电极表面,对其具有缓蚀作用。

A series of perylene diimide（PDI） derivatives based on pentaphenylbenzene backbone（n-PDI, n ？ 2, 3, 4） were synthesized by 2-（2-methoxyethoxy）-ethanol, triethylene glycol monomethyl ether, methyl tetraglycol, 3,4,9,10-perylenetetracarboxylic dianhydride as starting materials. By varying the staring materials, n-PDI（n= 2, 3, 4） with 2, 3, and 4 swallow-tail substituents were obtained. The structures of n-PDI（n= 2, 3, 4） were characterized by IR, ^1H NRM. Thermogravimetric analysis（TGA） and derivative thermogravimetry（DTG） show that the decomposition temperatures of n-PDI（n = 2, 3, 4） are all above 200℃, indicative of well thermal stability of n-PDI（n = 2, 3, 4） in corrosion additive field. The surface active parameters and the thermodynamic parameters of n-PDI were investigated. A series of surface active parameters were obtained from surface tension measurement. It indicated that n-PDI（n ？ 2, 3, 4） with the shorter ethoxy chain showed the higher surface activity. The thermodynamic parameters of micellization process and the gas-liquid interface adsorption process were derived from critical micelle concentration（CMC） at different temperatures. It indicated that micellization process and the gas-liquid interface adsorption process were spontaneous. Gibbs free energy of the micellization was determined mainly by entropy at low temperature. At higher temperature, however it was mainly dominated by enthalpy. SEM image showed that gemini surfactants on the zinc electrodes have corrosion inhibition.