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

这项拨款为研究一种制造新型三维聚合物基纳米复合材料的方法提供了资金，该复合材料具有定制设计的功能梯度特性。该研究的目的是合成具有不同刚度、强度和韧性值的特定区域的结构复合材料，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性液晶单体形成的。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原位。预计定向含有纳米管的液晶分子将导致纳米管的自排列，从而使复合材料具有增强的各向异性力学性能。纳米复合材料可以通过喷墨沉积工艺形成，预计在加工过程中可以通过改变应用场的方向来适应取向和成分的局部变化。对材料和工艺的建模将使三维纳米复合材料的定制设计具有卓越的性能，用于先进的应用。使用这种工艺，可以形成纳米管-聚合物复合材料，这种复合材料比现有的最好的碳纤维-环氧复合材料更坚硬、更坚韧，同时重量更轻。通过喷墨沉积的完全计算机化的固体自由形状制造加工可以直接生产纳米复合材料，并消除使用传统的铸造、锻造、加工或成型工艺以及使用昂贵的工具。这一过程快速而准确，并有可能形成大尺寸的复合材料结构。随意生产定制形状的能力使其能够在任何位置进行快速，灵活，定制的生产，例如在海上船舶上生产独一无二的关键复合材料部件。

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.