Ultrasound Alignment of Carbon Nanotubes in a Polymer Medium for Additive Manufacturing of Nanocomposite Materials

聚合物纳米复合材料由纳米级填充材料增强的聚合物基材料组成。特别是，与传统材料相比，与传统材料相比，定向碳纳米管增强的聚合物纳米复合材料具有潜在的更高的碳纳米管取向方向的强度/重量比和刚度/重量比。有几种方法可以在聚合物基质材料中对齐碳纳米管，包括拉伸、切片和基于电场和磁场的技术。然而，这些方法在效率和可扩展性方面受到限制。该奖项支持使用超声波以可扩展的方式排列聚合物材料中的碳纳米管的基础研究。研究结果有可能将超声引导的自组装与立体光刻添加剂制造工艺相结合，以制备具有定向碳纳米管的工程聚合物纳米复合材料。这些材料可以展示出与最先进的轻质材料相媲美或超过的机械性能，并可用于广泛的应用，包括航空航天、汽车和基础设施。本研究的目的是建立碳纳米管在光聚合物基质中的取向与超声引导自组装技术的操作参数之间的关系。为了实现这一目标，将采取试验性的方法。碳纳米管将使用表面活性剂和超声波分散在液体光聚合物中，并将使用超声波引导的自组装在光聚合物中创建排列的碳纳米管的线条图案。光致聚合物随后将使用立体光刻添加剂制造工艺固化成矩形样品。超声引导自组装技术的操作参数将有所不同：超声波频率从0.19到2.00 MHz，超声波驱动电压幅度从10到40伏，光聚合物层厚度从100到500微米，碳纳米管长度从10到100微米，碳纳米管质量分数从0.01到1%。碳纳米管在固化的光聚合物基质中的排列将使用一套表征工具来确定，其中包括扫描电子显微镜、电子计算机断层扫描和X射线计算机断层扫描。此外，碳纳米管的排列将使用赫尔曼斯取向因子和半最大全宽技术来量化。

Polymer nanocomposite materials consist of a polymer matrix material reinforced with a nanoscale filler material. In particular, polymer nanocomposite materials reinforced with aligned carbon nanotubes are of interest due to their potentially higher strength-to-weight and stiffness-to-weight ratios in the direction of the carbon nanotube alignment, compared to traditional materials. Several methods exist to align carbon nanotubes in a polymer matrix material, including stretching, slicing, and techniques based on electric and magnetic fields. However, these methods are limited in terms of efficiency and scalability. This award supports fundamental research on using ultrasound waves to align carbon nanotubes in a polymer material in a scalable fashion. Research results can potentially enable integrating ultrasound directed self-assembly with a stereolithography additive manufacturing process to fabricate engineered polymer nanocomposite materials with aligned carbon nanotubes. These materials can exhibit mechanical performance that may rival or exceed that of state-of-the-art lightweight materials, and can be used in a wide range of applications, including aerospace, automobile, and infrastructure. The objective of this research is to establish the relationship between alignment of the carbon nanotubes in the photopolymer matrix and operating parameters of the ultrasound directed self-assembly technique. An experimental approach will be followed to achieve this objective. Carbon nanotubes will be dispersed in liquid photopolymer using surfactant and sonication, and ultrasound directed self-assembly will be used to create line patterns of aligned carbon nanotubes within the photopolymer. The photopolymer will subsequently be cured into a rectangular specimen using a stereolithography additive manufacturing process. The following operating parameters of the ultrasound directed self-assembly technique will be varied: ultrasound wave frequency from 0.19 to 2.00 MHz, ultrasound wave driving voltage amplitude from 10 to 40 Volt peak-to-peak, the photopolymer layer thickness from 100 to 500 micrometer, carbon nanotube length from 10 to 100 micrometer, and carbon nanotube weight fraction from 0.01 to 1 weight percent. The alignment of the carbon nanotubes in the cured photopolymer matrix will be determined using a suite of characterization tools that include scanning electron microscopy, electron computed tomography, and X-ray computed tomography. Furthermore, the alignment of the carbon nanotubes will be quantified using the Hermans' orientation factor and the full-width at half maximum techniques.