I-Corps: Formation of thin films with self-assembled monolayers embedded on their surfaces

在许多应用中，薄膜被涂覆在材料的表面以改变其机械、热、电和光学特性。涂层必须是高度有序的二维晶体，具有特定的晶格间距，这取决于应用。例如，为了制造高效的太阳能电池减反射涂层，表面要有周期性图案的纹理，其波长与太阳辐射的波长相当。这可以通过在表面涂覆一层嵌入了单层颗粒的薄膜来实现。可以选择颗粒大小和颗粒之间的间距以获得所需的图案。这些颗粒涂层薄膜还可用于制造纳米光刻掩模、纹理疏水表面和具有规则孔的薄膜滤光片。这种膜过滤器可以用来精确控制药物输送贴片的传质速率，并根据蛋白质和其他大分子的大小来分离它们。毛细作用驱动的流体界面聚集是一种成熟的形成单分子膜的方法，但这些单分子膜的有序性很差。在所提出的技术中，在垂直于界面的方向上施加电场来控制自组装过程，从而获得几乎无缺陷的电中性纳米粒子的单分子膜。当存在两种或两种以上类型的粒子时，在组装的单分子层中存在分级顺序，可以通过选择合适的流体来优化该分级顺序。这项技术还允许我们根据应用程序适当地改变晶格间距。然后，将单层冻结到柔性薄膜的表面上，该薄膜可以转移到材料的表面以改变其表面属性。该技术易于实现，可应用于多种颗粒大小和类型，具有很高的可控性，这将在许多应用中具有优势。

In many applications, thin films are coated onto the surface of materials to modify their mechanical, thermal, electrical, and optical properties. The coatings must be highly ordered two-dimensional crystals with a specific lattice spacing which is application dependent. For example, to make a highly-efficient anti-reflection coating for solar cells, the surface is textured with a periodic pattern with the wavelength comparable to that of solar radiation. This can be achieved by coating the surface by a thin film with a monolayer of particles embedded on its surface. The particle size and the spacing between particles can be selected for obtaining the desired pattern. These particle coated thin films can also be used for making masks for nano-lithography, textured hydrophobic surfaces, and membrane filters with regular pores. The membrane filters could be used to precisely control the mass transfer rate of a drug-delivery patch, and to separate proteins and other macromolecules based on their sizes. Capillarity-driven clustering at fluid interfaces is a well-established method for forming monolayers, but those monolayers are poorly ordered. In the proposed technique an electric field in the direction normal to the interface is applied to control the self-assembly process so to obtain a virtually defect-free monolayer of electrically neutral nano-particles. When there are two or more types of particles present, there is a hierarchical order in the assembled monolayers which can be optimized by selecting a suitable fluid. The technique also allows us to vary the lattice spacing as appropriate to the application. The monolayer is then frozen onto the surface of a thin flexible film which can be transferred to the surface of a material to modify its surface properties. The technique is easy to implement and can be applied to a broad range of particle sizes and types with a high level of controllability which will be advantageous in many applications.