Controlling Microstructure of Hybrid Thin Films through Flow-Induced Orientation

复合材料的设计和加工是为了协同利用这两种成分材料的综合性能。生物矿化是生物有机体产生矿物的过程，通常会导致一个复合系统，其中矿物形成结构框架，而有机成分承担生物功能。珍珠层是一种贝壳材料，也被称为珍珠母，就是一个典型的例子，它由大量的无机碳酸钙(硬的和脆的)和一小部分的蛋白质(软的和硬的)组成。与单独的部件相比，它们在分层结构中的组合导致了出色的机械性能。这种精心组织的复合材料激发了科学家们大规模合成类似结构的材料用于实际应用的灵感，但他们的努力尚未被证明是成功的。基本的挑战是很难将大量的无机纳米材料整合到聚合物体系中，同时实现高度的组织化。该奖项支持基础研究，以探索一种简便的方法来制备具有珍珠层状微结构的杂化材料，并实现类似的杰出机械性能和其他重要功能。通过利用圆盘状颗粒的流动诱导取向，似乎可以以高速率制造材料。通过这种方法制备的复合膜将在包装中得到应用，具有更好的阻隔性能和耐腐蚀性。在这个项目中完全融入了提高年轻一代，特别是那些代表性不足的群体对科学和技术的兴趣的活动。这项研究将导致彻底了解血小板流动诱导取向和堆积的基本机制，这些机制可以帮助导致这些颗粒在复合薄膜中的最佳排列，以模拟珍珠层结构。系统地研究了流速、体系粘度、纳米片浓度和长宽比等因素以及相关的化学，以解决两个基本问题。首先，这些因素如何影响纳米薄片的排列和堆积？其次，纳米薄片和聚合物粘结剂之间的界面将如何影响最终的薄膜性能？除了珍珠状的结构和性能外，研究人员还旨在通过适当调整有机和无机成分的微观结构，进一步扩大形成三维杂化材料的范围，例如骨骼。

Composite materials are designed and processed to take synergistic advantage of the combined properties of the two component materials. Biomineralization, the process by which living organisms produce minerals, typically results in a composite system where the mineral forms the structural frame while an organic component assumes the biological function. Nacre, a shell material also known as mother of pearl, is a representative example, being composed of a large fraction of inorganic calcium carbonate (hard and brittle) and a small fraction of protein (soft and tough). Their combination in a layered structure leads to the outstanding mechanical properties in contrast to the individual components. Such carefully organized composites have inspired scientists to synthesize materials with a similar structure at a large scale for practical applications, but their efforts have not yet proven successful. The basic challenge is the difficulty of incorporating a large concentration of inorganic nanomaterials into a polymer system, and simultaneously achieving a high level of organization. This award supports fundamental research to explore a facile approach to prepare hybrid materials with a nacre-like microstructure and to achieve similar outstanding mechanical properties and other important functionalities. By taking advantage of flow-induced orientation of disc-like particles, the manufacturing of materials at a high rate appears to be possible. The composite films prepared through this approach should find application in packaging with improved barrier properties and corrosion resistance. Fully integrated within this project are activities to increase the interest in science and technology among the younger generation, particularly those in underrepresented groups.This research will lead to a thorough understanding of the fundamental mechanisms for the flow induced orientation and stacking of platelets that can help lead to optimal alignment of these particles in composite films to mimic the nacre structure. Factors such as flow rate, system viscosity, nanosheet concentration and aspect ratio, and related chemistry will be systematically investigated to address two fundamental questions. First, how do these factors affect the alignment and packing of nanosheets? Secondly, how will the interface between the nanosheets and the polymer binder affect the final thin film properties? In addition to the nacre-like structure and properties, the researchers also aim to further expand the scope to the formation of three-dimensional hybrid materials, such as bones, by properly tailoring the microstructure of the organic and inorganic components.