Gaussian random fields with two level-cuts-Model for asymmetric microemulsions with nonzero spontaneous curvature?
Gaussian random fields with two level-cuts-Model for asymmetric microemulsions with nonzero spontaneous curvature?
复制标题
DOI：
10.1063/1.1388558
复制
发表时间：
2001-08-22
影响因子：
4.4
通讯作者：
Zemb, T
中科院分区：
文献类型：
--
作者：
Arleth, L;Marcelja, S;Zemb, T
微乳液的微观结构由油域和水域之间的表面活性剂界面的热力学决定。由于该表面活性剂界面的自发曲率强烈依赖于温度，因此微乳液的微观结构也变得依赖于温度。在目前的工作中，我们假设界面的热力学由赫尔弗里希哈密顿量确定，并且界面可以通过高斯随机场的两个适当选择的水平切割来描述。然后可以将界面的自由能密度表示为高斯随机场的光谱分布的函数，使得可以通过执行相对于高斯随机场的光谱分布的自由能的函数最小化来确定使自由能最小化的微观结构。两个水平切割是该模型的一个重要特征，因为它们使我们能够模拟具有非零自发曲率以及水和油体积分数不等的微乳液。这再次使得模拟上述微乳液的温度驱动相转化成为可能。该模型还允许我们预测给定的水、油和表面活性剂成分和输入参数 H-0、kappa 的微乳液的微观结构，以及预测直接空间结构和散射结构因子。根据输入参数预测具有双连续结构、液滴结构或膨胀海绵状结构的微乳液，并在正空间和反空间中表示。散射峰位置的稀释图与实验结果非常吻合。 (C) 2001 年美国物理研究所。
The microstructure of a microemulsion is dominated by the thermodynamics of the surfactant interface between the oil and water domains. As the spontaneous curvature of this surfactant interface is strongly temperature dependent the microstructure of microemulsions also becomes temperature dependent. In the present work we have assumed that the thermodynamics of the interface is determined by the Helfrich Hamiltonian and that the interface can be described by two appropriately chosen level-cuts of a Gaussian random field. It is then possible to express the free energy density of the interface as a functional of the spectral distribution of the Gaussian random field so that the microstructure which minimizes the free energy can be determined by performing a functional minimization of the free energy with respect to the spectral distribution of the Gaussian random field. The two level-cuts are an important feature of the model since they allow us to model microemulsions with nonzero spontaneous curvature and with unequal volume fractions of water and oil. This again makes it possible to simulate the temperature driven phase inversion of the microemulsions described above. The model furthermore allows us to predict the microstructure of the microemulsion for a given composition of water, oil and surfactant and input parameters H-0, kappa and as well as to predict direct space structures and scattering structure factors. Microemulsions with bicontinuous structures, droplet structures or swollen sponge-like structures are predicted dependent on the input parameters and represented in direct and inverse space. Dilution plots for scattering peak positions are in good agreement with experimental results. (C) 2001 American Institute of Physics.