Collaborative Research: Multilayer Co-extrusion Processing of Thermally Conductive Polymer Nanocomposites

聚合物复合材料是具有两个或更多组分的材料系统，在加工过程中可以通过选择和放置单个材料来定制所产生的性能。聚合物通常是导热性差的导体，但当与导热纳米填料结合时，可以产生具有理想导电性的聚合物复合材料，用于微电子封装，led照明基板和太阳能电池板密封等应用。多层共挤是一种新型的制造技术，为制备具有理想结构和性能的聚合物复合材料提供了一条有前途的途径。通过合理的材料设计、先进的制造和结构性能测量，该奖项确定了影响聚合物复合材料热传导的关键因素，并建立了一种聚合物加工方法来制造具有重大社会经济影响的导热纳米复合材料。这项高度跨学科的研究为从高中到研究生的不同背景的学生提供了丰富的教育和培训机会。多层共挤工艺与前驱体材料的合理设计相结合，可以生产出具有理想微观结构的纳米复合材料——形成纳米填料渗透网络，实现高效的热传导。然而，仍有几个科学问题有待解决，例如最佳的纳米填料特性，在低填料负载下形成渗透网络的最有效方式，以及期望的热接触形态。该项目旨在通过系统的研究来填补知识空白，该研究涵盖了基于对多尺度热传递机制的基本理解的设计材料的整个研究循环，调整制造工艺以实现所需的微观结构，并表征所得复合材料的导热性以获得新的设计见解。该合作研究验证了一个中心假设，即控制良好的多层共挤出工艺可以产生导热聚合物复合材料，该复合材料具有由各向异性纳米填料之间的直接接触形成的真正的渗透网络和低接触热阻的最佳网络形态。这个研究项目是一个团队之间的合作，一个团队探索多层纳米复合材料的共挤压，以产生所需的微观结构，另一个团队研究热传输特性，以提供对材料设计和性能的见解。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Polymer composites are materials systems with two or more components where the resulting properties can be tailored by the choice and placement of the individual materials during processing. Polymers are normally poor thermal conductors, but when combined with thermally conductive nanofillers, can result in a polymer composite with desirable conductivity for applications such as microelectronic packaging, substrates for LED-lighting, and solar panel seals. Multilayer co-extrusion, a novel manufacturing technology, provides a promising route to fabricate polymer composites of desirable architecture and properties. Through rational materials design, advanced manufacturing, and structure-property measurements, this award identifies key factors that affect heat conduction in polymer composites and establishes a polymer processing approach to manufacture thermally conductive nanocomposites for applications with significant socio-economic impact. This highly interdisciplinary research provides rich education and training opportunities for students of diverse backgrounds from high-school to graduate level. Multilayer co-extrusion processing, when combined with proper design of the precursor materials, could produce nanocomposites with desired microstructure - forming a nanofiller percolation network to enable efficient heat conduction. However, several scientific questions remain to be answered, such as optimal nanofiller characteristics, the most effective way to form percolation networks at a low filler loading, and the desired thermal contact morphology. This project aims to fill the knowledge gap through systematic studies covering the entire research loop of designing materials based on fundamental understanding of multiscale thermal transport mechanisms, tuning the manufacturing processes to achieve desired microstructures, and characterizing the thermal conductivity of the resulting composites to obtain new design insights. The collaborative study tests the central hypothesis that well-controlled multilayer co-extrusion processing can produce thermally conductive polymer composites with true percolation networks formed by direct contacts between anisotropic nanofillers and an optimal network morphology with low contact thermal resistance. This research project is a collaboration between a team that explores co-extrusion of multilayer nanocomposites to generate the desired microstructures and a team that characterizes thermal transport properties to provide insights into materials design and performance.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.