A Scalable Single-Step Process to Create Multifunctional Coatings

1335787 PI: Bhatia Films based on colloidal dispersions are widely encountered as paints and coatings, with emerging applications in energy, data storage, and electronic devices. Oftentimes, there is a need for multifunctional coatings, where the upper surface of the film provides a specific functionality such as corrosion resistance, enhanced gloss, or anti-bacterial properties. To impart this structure, a multi-step deposition process can be used. Alternatively, a single-step process can be used by casting a dispersion of particles with various functionalities. If particles with varied sizes and interactions are used, a self-assembled structured coating with a prescribed concentration profile could be obtained. Previous theoretical work has highlighted the contribution of both hydrodynamics and colloidal interactions to the formation and concentration distribution in multicomponent films. However, experimental verification of this model has been hampered by limitations of characterization methods to determine structure and composition throughout the film and a lack of model systems in which the interaction potential of each component can be systematically varied. In this project, we will develop a fundamental understanding of how particle size and interactions can be used to tune the structure of multicomponent films, using a combined theoretical and experimental approach. The project is an international collaboration between PI Surita Bhatia, who brings expertise in characterization of colloidal materials and scattering techniques, and Prof. Alexander Routh (Cambridge University), an expert in colloidal hydrodynamics who brings expertise in theoretical modeling of film formation. The proposed work leverages world-class facilities for x-ray characterization at Brookhaven National Laboratory (BNL), where Bhatia is an affiliate, and benefits from the expertise of the BP Institute for Multiphase Flow at Cambridge University, of which Routh is a member. Our study distinguishes itself from previous work in that we will use techniques such as small-angle scattering to quantify the interparticle potential of our experimental systems, enabling a more direct comparison to theoretical predictions, and in the use of advanced scattering techniques such as grazing incidence SAXS (GI-SAXS) to probe structure and composition throughout the film. The latter technique offers significant advantages over techniques such as AFM, which probes only surface structure, and x-ray reflectivity. The research will impact a number of industrial applications, most directly the coatings industry. It will contribute to the development of single-step film formation processes that would decrease production time and costs of multifunctional films. We will work with industrial contacts to hold focused symposia at conferences to disseminate the results to both academic and industrial audiences. Concepts from the research will be incorporated into core undergraduate and graduate courses. Broader impacts related to human resources include training of a graduate student in both experimental and theoretical techniques for soft materials, interaction of this graduate student with industrial scientists, and the development of a trans-Atlantic collaboration between two leading soft matter groups. Bhatia has a demonstrated commitment to recruitment and retention of female, minority, and disabled researchers and will focus on recruiting under-represented students for this project.