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)更好地了解激光驱动基质辅助夹带聚合物分子和纳米元素的基本机理，以及(B)将这一理解应用于开发和优化制备聚合物基纳米复合薄膜和涂层的新技术。以聚合物基质-碳纳米管纳米复合材料为模型体系，确定了高效制备增强纳米元素在聚合物基质中均匀分散的纳米复合膜的条件。烧蚀羽流的原位表征和沉积薄膜的非原位表征将旨在深入了解导致卷吸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拟将有助于解释实验数据，并将指导探索沉积纳米复合薄膜的实验参数空间，同时最大限度地减少对原始分子结构的修改，并最好地控制增强纳米元素的分布。基于短激光脉冲加热的挥发性基质的分子夹带效应，纳米复合薄膜沉积的研究结果将对当前的应用范围产生更广泛的影响。现代塑料生产的一个共同趋势是增强具有高强度/刚性的第二相聚合物。在过去十年中出现的一种替代传统聚合物复合材料的是一类聚合物纳米复合材料，它包含特征尺寸小于100 nm的纳米元素的均匀分散，例如碳纳米管(CNTs)。实现碳纳米管-聚合物复合材料最佳性能的主要限制因素之一是难以产生碳纳米管在聚合物基质中的均匀分散和排列。高浓度(5-6wt.%)碳纳米管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.