Multiscale analysis of the dynamic interactions of nanoparticles and oil-soluble surfactants at liquid interfaces

颗粒稳定的乳液体系在不同领域中具有广泛的工业用途，例如在石油回收或水治理中的浮选，在营养产品、化妆品和药物制剂中以及在复合材料和陶瓷的材料加工中。在许多这些应用中，乳液系统可以是相当复杂的，其中各种类型的颗粒和表面活性分子协同或竞争作用以稳定液滴界面。由于这种复杂性，稳定的多组分乳液体系的配制通常仍然是资源密集型的试错过程。特别地，混合界面膜的堆积密度和渗滤目前既不能通过调节已建立的系统参数如浓度、pH或表面活性剂类型来控制，也没有足够的计算模型可以支持这样的任务。该项目的目的是将非均质和多组分石油的分子细节联系起来，含有表面活性剂分子和纳米颗粒的混合物的水界面对这些膜的宏观行为的影响。这就需要一个多尺度的方法，在每一个尺度上都必须仔细选择足够的复杂程度，以达到对系统有意义和有效的理性描述和理解。基于这种理解，我们的目标是生成设计规则，使我们能够通过作用于一些选定的和容易获得的量和参数，例如油/水表面张力和等效平面的宏观接触角，来定制不同类型的颗粒/表面活性剂乳液系统的形成。为了实现这一目标，我们计划访问相同的特征观测值集（特别是：接触角、界面能、吸附能、电子密度分布、界面微观结构和界面流变学）两者均来自实验以及来自原子和介观模拟。如果从这些互补的方法中获得相同的可观测值，我们可以有把握地假设模拟模型是实验现实的忠实代表。这样，我们就可以很好地描述颗粒在表面活性剂负载界面上的吸附和决定乳状液体系类型的颗粒膜中的结构形成，这种实验和模拟方法的结合将使我们对混合界面膜的形成有前所未有的了解。通过这种方法，我们的目标是在基础水平上扩展我们对多组分界面系统的知识，以及根据可预测的配方规则形成复杂的乳液系统。这样的设计规则将极大地促进资源密集型的配制过程，这对于从制造冰淇淋到加工分级结构的多孔陶瓷的广泛的工业过程是必要的。

Particle-stabilized emulsion systems see widespread industrial use in diverse areas, such as floatation in oil recovery or water remediation, in nutritional products, cosmetics and pharmaceutical formulations as well as in materials processing of composites and ceramics. In many of these applications the emulsion systems can be quite complex with various types of particles and surface-active molecules acting in synergy or competition to stabilize the droplet interface. Because of this complexity, the formulation of stable multi-component emulsion systems is usually still a resource-intensive trial and error process. Particularly, the packing density and percolation of mixed interfacial films can currently neither be controlled by adjusting established system parameters like concentrations, pH or surfactant types, nor are there adequate computational models that could support such a task.The aim of this project is to link the molecular details of heterogeneous and multi-component oil/water interfaces containing a mixture of both surfactant molecules and nanoparticles to the macroscopic behavior of these films. This requires a multiscale approach in which an adequate degree of complexity has to be carefully selected at every scale to reach a meaningful and efficient rational description and understanding of the system. From this understanding, we aim to generate design rules that allow us to tailor the formation of different types of particle/surfactant emulsion systems by acting on a few selected and easily accessible quantities and parameters, such as the oil/water surface tension and the macroscopic contact angle of an equivalent flat surface.To achieve this aim, we plan to access the same set of characteristic observables (in particular: contact angles, interfacial energies, adsorption energies, electron density profiles, interfacial microstructure and interfacial rheology) both from experiments and from atomistic and mesoscopic simulations. If the same values of observables are obtained from these complementary approaches, we can safely assume that the simulated models are a faithful representation of the experimental reality. In this way, we will have achieved a satisfying description of particle adsorption at the surfactant-laden interface and of structure formation in the particle film which determines the type of emulsion system.This combination of experimental and simulation methods will allow unprecedented insight into the formation of mixed interfacial films. With this approach we aim both to expand our knowledge on multicomponent interfacial systems on a fundamental level, as well as to enable the formation of complex emulsion systems based on predictable formulation rules. Such design rules will greatly facilitate the resource-intensive formulation processes which are necessary for a wide range of industrial processes from making ice cream to processing hierarchically structured porous ceramics.