Nanostructured Composite Coatings to Harden and Toughen Polymer Surfaces

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Owing to their low density, high toughness, ease of processing and low cost, polymers are playing increasingly important roles in a broad set of applications, including electronics, vehicles, building materials, and industrial and household appliances. Compared to metals and ceramics, however, polymers have rather poor scratch- and wear-resistance. A common approach to enhance the scratch/wear resistance of polymers is to add hard coatings on their surfaces. However, many conventional hard coatings suffer from poor adhesion to the polymer and can crack easily. Furthermore, the conventional deposition methods for hard coatings are often done under negative pressure, making them expensive and challenging to implement for large-area processing. The goal of this work is to investigate a new class of nanostructured coatings that have high scratch and crack resistance and can be produced using an inexpensive scalable method. This work is motivated by recent success in creating nanocomposite coatings with extremely high concentrations of nanoparticles based on infiltration of polymers into nanoparticle films. These coatings can be formed directly on the surface of polymers to produce coatings that have very strong adhesion and high scratch resistance. Scratch resistant nanocomposite hard coatings can potentially be used as key components of next-generation energy storage and conversion devices as well as optical, biosensors and electronic devices. Also, such materials have applications as barriers in electronics and food packaging. The team will develop modules demonstrating the properties of composite materials for use at outreach events planned for students, teachers and the general public.This project will establish the processing-structure-property relationships of brick-and-mortar structured nanocomposite coatings produced via capillary rise infiltration (CaRI) of poly(methylmethacrylate) into films of gibbsite nanoplatelets. The project is a collaboration between two investigators: Lee, an expert in the fabrication and structural and optical characterization of nanostructured materials, and Turner, an expert in materials and mechanics. The project will address fundamental issues that must be understood and overcome to advance CaRI materials and the general area of nanocomposites. Specifically, the effect of spatial confinement on the capillary rise and transport of large polymers through nanoporous media will be studied by changing the molecular weight of the polymer and its size relative to the characteristic pore size in the nanoplatelet film. Furthermore, by taking advantage of the versatility and tunability of the CaRI process, the relationship between the internal structure of the composite coatings and their mechanical and optical properties will be established. Through processing, characterization, and modeling, we will develop a holistic understanding of processing-structure-property relationship of CaRI composites.