Supercritical Fluid Assisted Processing of SWNT/Polymer Composites

该基金为开发一种可扩展的连续加工方法提供资金，该方法可以生产出具有剥离纳米管束的碳单壁纳米管(SWNT)/聚合物复合材料。这种技术的发展非常重要，因为为了优化SWNT/聚合物复合材料的性能，必须将SWNT从束中分离出来。实现这一关键目标的方法是使用超临界CO2辅助双螺杆挤出来实现单壁碳纳米管的分离和分散。为了实现超临界流体和SWNT之间的润湿，SWNT束的表面将发生化学变化，使超临界流体优先迁移到SWNT束的表面。在离开挤出机/压力室时，超临界流体将膨胀，因为它变成了气体。如果成功，这种加工方法将促进单壁碳纳米管的使用，从而增加降低价格所必需的需求。该工艺将允许商业规模数量的生产和更大规模的复合材料性能测试。此外，这是一个无溶剂的过程，是环保的。该项目还将有助于对非均相体系中CO2溶解度热力学的基本理解，以及我们对宽高比和表面积在控制纳米复合材料性能中的作用的理解。最后，通过分析表面改性（界面）、混溶性和溶解度以及加工条件获得的理解将增加我们控制和创造未来材料的能力。当我们解决商业规模工艺的挑战，以一种廉价和环保的方式实现出色的分散时，更广泛的社会影响之一将是改善潜在产品的性能，并使含有swnt的新产品的制造成为可能。

This grant provides funding for creating a scaleable and continuous processing method that leads to carbon single-walled nanotube (SWNT)/polymer composites with exfoliated nanotube bundles. Development of such a technique is important because in order to optimize the properties of SWNT/polymer composites, the SWNTs must be separated from the bundles. The approach to meeting this critical goal is to use supercritical CO2 assisted twin-screw extrusion to achieve separation and dispersion of SWNTs. In order to achieve wetting between the supercritical fluid and the SWNTs, the surface of the SWNT bundles will be chemically altered such that the supercritical fluid will preferentially migrate to the surface of the SWNT bundles. Upon exiting the extruder/pressure chamber, the supercritical fluid will expand, as it becomes gas.If successful, the processing method will promote the use of SWNTs and thus increase demand that is necessary to reduce the price. The process will allow the production of commercial scale quantities and broader scale testing of composite properties. In addition, this is a solvent free process that is environmentally friendly. This project will also contribute to the fundamental understanding of the thermodynamics of CO2 solubility in heterogeneous systems, as well as our understanding of the role of aspect ratio and surface area in controlling nanocomposite properties. Finally, the understanding gained through the analysis of surface modification (interface), miscibility and solubility, and processing conditions will increase our ability to control and create future materials. As we address the challenge of a commercial scale process that achieves excellent dispersion in a manner that is inexpensive and environmentally friendly, one of the broader societal impacts will be to improve the properties of potential products and enable the manufacture of new products containing SWNTs.