Laser-Assisted Deposition of Polymer-Matrix Nanocomposites: A Combined Experimental and Computational Study

提出的研究计划的研究目标是：(A)更好地理解激光驱动基质辅助夹带聚合物分子和纳米级元素的基本机制；(B)将这种理解应用于聚合物基纳米复合薄膜和涂层沉积的新技术的开发和优化。以聚合物基体-碳纳米管纳米复合材料为模型体系，研究了在聚合物基体中均匀分散增强纳米元素的高效制备纳米复合材料薄膜的条件。烧蚀羽流的原位表征结合沉积膜的非原位表征将旨在深入了解导致夹带现象的不同过程的相互作用。与实验研究并行进行的多尺度计算模型将有助于解释实验数据，并将指导探索纳米复合膜沉积的实验参数空间，同时对原始分子结构进行最小的修改，并对增强纳米元素的分布进行最佳控制。基于短激光脉冲加热的挥发性基质的分子夹带效应，在纳米复合膜沉积研究中获得的结果将对当前的一系列应用产生更广泛的影响。现代塑料生产的一个共同趋势是用高强度/刚度的第二相增强聚合物。在过去十年中出现的一种替代传统聚合物复合材料是一类聚合物纳米复合材料，它包含均匀分散的特征尺寸小于100纳米的纳米元素，如碳纳米管（CNTs）。影响碳纳米管-聚合物复合材料最佳性能的主要限制因素之一是碳纳米管难以在聚合物基体中均匀分散和排列。在高（5-6 wt.%）碳纳米管浓度下，材料粘度的急剧增加限制了大多数制造技术的能力。基质辅助激光沉积有望克服这些限制，同时扩大可用于实验探索和应用的成分和结构的范围。

The research objectives of the proposed research program are (A) to gain a better understanding of the fundamental mechanisms of laser-driven matrix-assisted entrainment of polymer molecules and nanoscale elements and (B) to apply this understanding for the development and optimization of a novel technique for deposition of polymer-matrix nanocomposite thin films and coatings. Using a polymer matrix - carbon nanotube nanocomposite as a model system, the conditions for efficient fabrication of nanocomposite films with a uniform dispersion of reinforcing nano-elements in a polymer matrix will be identified. In-situ characterization of the ablation plume combined with ex-situ characterization of the deposited films will be aimed at getting insights into the interplay of different processes responsible for the entrainment phenomenon. Multiscale computational modeling, performed in parallel with experimental investigations, will help with interpretation of experimental data and will guide the exploration of the space of the experimental parameters for deposition of nanocomposite films with minimum modification of the original molecular structure and the best control over the distribution of the reinforcing nanoelements. The results obtained in the proposed study for nanocomposite film deposition will have a broader impact on a range of current applications based on the effect of molecular entrainment by a volatile matrix heated by a short laser pulse.A common trend in the production of modern plastics is the reinforcement of polymers with a high strength/stiffness second phase. An alternative to conventional polymer composites which has emerged during the last decade is a class of polymer nanocomposites containing a uniform dispersion of nanoelements with characteristic sizes less than 100 nm, such as carbon nanotubes (CNTs). One of the main limiting factors in achieving the best performance of CNT-polymer composites is the difficulty in producing a uniform dispersion and alignment of CNTs in polymer matrices. A sharp increase of material viscosity at high (5-6 wt.%) concentrations of CNTs limits the capabilities of most fabrication techniques. Matrix-assisted laser deposition has a promise of overcoming these limitations while widening the range of compositions and structures accessible for experimental exploration and application.