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.
