论文部分内容阅读
利用分子动力学模拟方法研究了系列离子液体型Gemini咪唑表面活性剂在水溶液中的表面活性和胶束化能力.模拟结果表明,压力张量法得到的表面张力模拟值偏小,需乘以修正系数矫正;分子动力学模拟得到的临界胶束浓度变化规律与实验相符,可以定性比较不同结构的离子液体型Gemini咪唑分子间的胶束化能力;温度的升高会加剧分子的热运动,不利于离子液体型Gemini咪唑表面活性剂在水溶液中形成胶束;此外,研究还发现联接基不同的离子液体型Gemini咪唑表面活性剂可能遵循不同的胶束化机理.S≤6时,单个分子自组装成胶球后发生聚合形成大胶团.随着咪唑上长烷烃链碳数的增加,[Cn-4-Cnim]胶束化能力提高;而随着联接链长度增加,[C10-S-C10im]胶束化能力降低;当S>6时,分子联接基弯曲并伸入其它分子烷烃链内部以减小头基分离力,从而形成稳定的胶束或胶团.随着联接基团亚甲基数的增加,头基斥力减小,附加疏水相互作用增强,[C10-S-C10im]胶束化能力提高.
The molecular dynamics simulation method was used to study the surface activity and micelle ability of a series of ionic liquid Gemini imidazole surfactants in aqueous solution. The simulation results show that the simulated tensional values obtained by the pressure tensor method are small and need to be corrected by the correction factor . The change of the critical micelle concentration obtained by molecular dynamics simulation is in good agreement with the experiment, and the micellarization ability between different ionic liquid Gemini imidazoles can be qualitatively compared. The increase of temperature will aggravate the thermal movement of the molecule, which is unfavorable to the ion Liquid Gemini imidazole surfactant forms micelles in aqueous solution.In addition, the study also found that the ionic liquid Gemini imidazole surfactant with different coupling groups may follow different micelle mechanism.When S≤6, the single molecule self-assemble into The [Cn-4-Cnim] micellization ability increased with the increase of the carbon number of the long paraffin chain on the imidazole. With the increase of the length of the coupling chain, [C10-S-C10im] When S> 6, the molecular linker bends and extends into the interior of other molecular alkane chains to reduce the separation force of the head group, thus forming a stable micelle or micelles .As the linker Increasing the number of sub-group, the head group is reduced repulsion, hydrophobic interaction additional reinforcement, [C10-S-C10im] micellization capacity.