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

在许多应用中，薄膜被涂覆到材料表面上以改变其机械、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，为了制造用于太阳能电池的高效抗反射涂层，表面被纹理化为具有与太阳辐射的波长相当的波长的周期性图案。这可以通过用嵌入其表面上的单层颗粒的薄膜涂覆表面来实现。可以选择颗粒尺寸和颗粒之间的间距以获得期望的图案。这些颗粒涂覆的薄膜也可用于制造用于纳米光刻、纹理化疏水表面和具有规则孔的膜过滤器的掩模。膜过滤器可用于精确控制药物传递贴片的传质速率，并根据其大小分离蛋白质和其他大分子。在流体界面处的毛细作用驱动的聚集是用于形成单分子层的成熟方法，但是那些单分子层是无序的。在所提出的技术中，在垂直于界面的方向上施加电场以控制自组装过程，从而获得电中性纳米颗粒的几乎无缺陷的单层。当存在两种或更多种类型的颗粒时，在组装的单层中存在分级顺序，其可以通过选择合适的流体来优化。该技术还允许我们根据应用程序适当地改变晶格间距。然后将单层冷冻到薄的柔性膜的表面上，该柔性膜可以转移到材料的表面以改变其表面性质。该技术易于实施，并且可以应用于具有高水平可控性的宽范围的颗粒尺寸和类型，这在许多应用中将是有利的。

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.