Department of Chemical Engineering, Princeton University, Princeton, New Jersey 08540, USA.
J Chem Phys. 2009 Sep 21;131(11):114901. doi: 10.1063/1.3227905.
A lattice model for diblock surfactants that incorporates orientational bonding has been developed for studying self-assembly in dilute solutions. Using grand canonical Monte Carlo simulations with histogram reweighting and mixed field finite size scaling, we examine the effect of amphiphile architecture on phase transitions and distinguish between first order transitions that create a disordered liquid phase and higher order transitions that indicate the formation of finite sized aggregates. As the solution temperature increases, we find that the critical micelle concentration for the orientational bonding model surfactants reaches a minimum value at a temperature that can be controlled by varying the number of bonding orientations between the solvophobic surfactant monomers and the implicit solvent. This trend is qualitatively similar to experimental data for ionic and nonionic surfactants in aqueous solutions. A comparable dependence on temperature is observed in the limit of amphiphile solubility for phase separating systems. None of the model surfactants considered here undergo both a first and a higher order transition over the range of densities and temperatures examined.
已经开发出一种用于研究稀溶液中自组装的嵌段表面活性剂格点模型，该模型包含了取向键合。通过使用具有直方图重新加权和混合场有限尺寸标度的巨正则蒙特卡罗模拟，我们研究了两亲物结构对相转变的影响，并区分了产生无序液相的一级转变和表明有限尺寸聚集体形成的高级转变。随着溶液温度的升高，我们发现，具有取向键合模型表面活性剂的临界胶束浓度在可以通过改变疏水性表面活性剂单体和隐溶剂之间的键合取向数来控制的温度下达到最小值。这种趋势与在水溶液中的离子型和非离子型表面活性剂的实验数据定性相似。在相分离体系中，亲脂性溶解度的极限处观察到类似的温度依赖性。在所研究的密度和温度范围内，这里考虑的模型表面活性剂都没有经历一级和高级转变。
