Shaping of Porous Nanostructures by Assembly and Disassembly Methods

该项目旨在开发用于制造具有各种成分和预先设计的尺寸和形状的多孔纳米颗粒（NPs）的化学技术，其中一些尚未通过现有技术获得。该方法将基于模板化具有可控中孔结构的分级多孔结构，并将这些结构拆卸成其构建块。纳米铸造技术将被用来创建复制结构和复合结构与广泛的组成。NP的物理性质将与粒度和形状相关。多孔NP将被官能化以改变其本体和表面性质。新的机会将出现，以创建扩展的2D或3D模式和复杂的结构与新的架构从功能构建块。已经提出了大量的纳米颗粒的应用，其中一些将受益于通过所提出的方法获得的额外孔隙率（介孔激光器、靶向药物递送系统、荧光标记主体、具有短扩散路径的NP催化剂、超级电容器、储氢系统）、具有可控纵横比和曲率的新形状（聚合物增强，磁流变流体中的磁性载体）和形成复合颗粒（磁性标签，高容量电极）的能力。由于该项目的多学科性质，学生将成为广泛的最先进的合成和表征技术的专家，涉及化学，物理，材料科学和工程的概念，使他们做好充分准备，以应对先进材料设计中的复杂挑战。为了吸引那些对科学只有短暂兴趣，但可能对材料化学的美学方面感兴趣的观众，将开发一个展示视觉上吸引人的纳米结构的海报展览，在当地博物馆和网上展出。%%具有确定尺寸和结构的多孔纳米物体特别令人感兴趣，例如，作为酶的胶囊，药物递送的手段，或用于较大纳米结构的构建块。以有针对性和可控的方式生产微小的三维物体，并且尽可能简单和有效，仍然是科学家们面临的挑战。在拟议的研究中，将开发新的工艺来生产纳米级立方体和其他有趣的形状，这些形状通常无法通过传统方法获得。而不是从更小的单元构建粒子，将使用更大的格子状结构的受控分解。许多传统的纳米颗粒生产方法都存在问题，因为生长的颗粒往往会聚集在一起，难以达到均匀的尺寸。颗粒的形状几乎不受影响。另一种待研究的方法是首先在一个超小的模具中建立一个网格结构，然后将其拆卸以获得所需的形状。用于网格的模具是微小的塑料球体，它们像盒子里的大理石一样组装起来。在这种结构中的球体之间，存在小的成形空间，这些空间将充满前体，当球体通过加热烧掉时，这些前体转化为具有微孔的成形纳米颗粒。通过改变模具，可以控制所得海绵状颗粒的尺寸和形状。成形的多孔纳米颗粒为复杂纳米结构提供了一个起点，在储能，检测和制药方面具有潜在的应用。参与该项目的学生将获得设计对提高美国技术竞争力至关重要的复杂材料所需的广泛的科学和工程技能。为了吸引那些对科学只感兴趣，但可能对材料化学的美学方面感兴趣的观众，将开发一个展示视觉上吸引人的纳米结构的海报展览，在当地博物馆和网络上展出。

This project aims to develop chemical techniques for fabricating porous nanoparticles (NPs) with a variety of compositions and predesigned sizes and shapes, some of which are not yet accessible by existing techniques. The approach will be based on templating hierarchical porous structures with controllable mesopore architectures and disassembly of such structures into their building blocks. Nanocasting techniques will be employed to create replicate structures and composite structures with a wide range of compositions. Physical properties of the NPs will be correlated with particle sizes and shapes. The porous NPs will be functionalized to modify their bulk and surface properties. New opportunities will arise to create extended 2D or 3D patterns and complex structures with novel architectures from the functional building blocks. A large number of applications have been suggested for NPs, and some of these would benefit from the additional porosity obtained by the proposed methods (mesoporous lasers, targeted drug-delivery systems, fluorescent tag hosts, NP catalysts with short diffusion paths, supercapacitors, hydrogen storage systems), new shapes with controllable aspect ratios and curvature (polymer reinforcement, magnetic carriers in magnetorheological fluids) and the ability to form composite particles (magnetic tags, high capacity electrodes). Because of the multidisciplinary nature of this project, students will become experts in a broad range of state-of-the-art synthetic and characterization techniques, involving concepts from chemistry, physics, materials science, and engineering, so that they are well prepared to tackle the complex challenges in advanced materials design. To reach an audience that may have only passing interest in science but may be attracted to the aesthetic aspects of materials chemistry, a poster exhibition showcasing the visually appealing nanostructures will be developed for display in local museums and on the web.%%%Porous nano-objects with defined sizes and structures are particularly interesting, for example, as capsules for enzymes, a means of drug delivery, or building blocks for larger nanostructures. Producing tiny, three-dimensional objects in a targeted and controlled manner-and as simply and efficiently as possible-remains a challenge for scientists. In the proposed research, new processes will be developed for the production of nanoscopic cubes and other interesting shapes that are not usually accessible by conventional methods. Instead of building particles from smaller units, controlled disassembly of larger, lattice-like structures will be used. Many conventional methods for the production of nanoparticles suffer because the growing particles tend to clump together, making it difficult to achieve a uniform size. The shape of the particles can hardly be influenced at all. The alternate approach to be studied involves first building up a lattice structure in an ultrasmall mold and then disassembling it to get the desired shape. The molds used for the lattice are tiny plastic spheres, which assemble themselves like marbles in a box. Between the spheres in this structure, there are small, shaped spaces, which will be filled with precursors that convert into shaped nanoparticles with tiny pores when the spheres are burnt off by heating. By altering the mold, the sizes and shapes of the resulting, sponge-like particles can be controlled. The shaped, porous nanoparticles provide a starting point for complex nanostructures with potential applications in power storage, detection and pharmaceutics. Students participating in the project will acquire broad scientific and engineering skill necessary to design the complex materials critical for advancing America's technological competitiveness. To reach an audience that may have only passing interest in science but may be attracted to the aesthetic aspects of materials chemistry, a poster exhibition showcasing the visually appealing nanostructures will be developed for display in local museums and on the web.