Self-Assembled Liquid Crystal Thermoset 3-D Nano-Composites With Functionally Graded Properties

这笔资金用于研究一种新的三维聚合物基纳米复合材料的制备方法，该复合材料具有定制设计的功能梯度特性。这项研究的目的是合成具有特定区域的结构复合材料，这些区域具有不同的刚度、强度和韧性值，以优化复合材料的整体机械和热性能。感兴趣的材料是由含有碳纳米管的化学反应的液晶单体形成的。液晶单体的独特之处在于，它们可以通过磁场或电场选择性地定向，然后通过单体的原位光反应锁定在适当的位置。预计，定向包含纳米管的液晶分子将导致纳米管的自对准，从而产生具有增强的各向异性力学性能的复合材料。该纳米复合材料可以通过喷墨沉积过程形成，并且预计可以通过在加工过程中改变外加电场的方向来适应对准和成分的局部变化。对材料和工艺进行建模将能够为高级应用定制设计具有优异性能的三维纳米复合材料。使用这种工艺，有可能形成比最好的现有碳纤维-环氧复合材料更坚硬、更韧性、同时重量更轻的纳米管-聚合物复合材料。通过喷墨沉积的完全计算机化的固体自由形状制造工艺可以直接生产纳米复合材料，并消除使用传统的铸造、锻造、机械加工或模制工艺和使用昂贵的工具。该工艺快速、准确，有可能形成大尺寸的复合材料结构。随心所欲地生产定制形状的能力使其能够在任何地点进行快速、灵活的定制生产，例如在海上生产独一无二的关键复合材料部件的船舶上。

This grant provides funding for research into a method for fabricating a new class of three-dimensional polymer matrix nanocomposites with custom designed functionally graded properties. The objective of the research is to synthesize structural composites designed with specific regions that have different stiffness, strength, and toughness values that optimize the overall mechanical and thermal performance of the composite. The materials of interest are formed from chemically reactive liquid crystal monomers containing carbon nanotubes. Liquid crystal monomers are unique in that they can be selectively oriented by magnetic or electric fields and can then be locked in place by photoreaction of the monomers in-situ. It is anticipated that orienting the liquid crystal molecules which contain nanotubes will cause self-alignment of the nanotubes, resulting in composites that have enhanced anisotropic mechanical properties. The nanocomposites can be formed by an inkjet deposition process and it is anticipated that local variations in alignment as well as composition can be accommodated by changing the direction of the applied field during processing. Modeling the material and process will enable the custom design of three dimensional nanocomposites with superior performance for advanced applications.Using this process, it is possible to form nanotube-polymer composites that are stiffer, tougher, and at the same time lighter weight than the best available carbon fiber-epoxy composites. Fully computerized solid freeform fabrication processing via inkjet deposition could enable the direct production of nano-composites and eliminate the use of conventional casting, forging, machining, or molding processes and the use of expensive tooling. This process is fast and accurate and is potentially capable of forming large sized composite structures. The ability to produce custom shapes at will lends itself to rapid, flexible, customized production at any location such as on ships at sea for production of one-of-a-kind critical composite components.