Collaborative Research: Deciphering the nanoscale interactions during mineral nucleation and scale formation on polymer surfaces

Mineral precipitation, or the formation of solid mineral phases from solutions, is a process of great importance in the natural environment and engineered systems. Mineral scaling on surfaces, or the unwanted deposition of mineral precipitates, poses a technological challenge to many industrial processes. In membrane-based water treatment, mineral scaling of polymer membranes decreases membrane flux, diminishes energy efficiency, and shortens membrane module lifespan. In the oil and gas industry, mineral scale deposition on the interior surface of pipes can result in complete blockage of pipelines and disrupt oil and gas production. Despite its importance, the role of polymeric solid substrates on mineral scaling is poorly understood. This research aims to understand how the surface characteristics of polymers impact the formation of mineral scales. The investigators will employ combined experimental characterization and theoretical analysis to examine the nanoscale interactions that drive mineral scale formation on polymeric substrates. The findings of this work will inform design of anti-scaling polymer surfaces in submerged aqueous environments, which will bring significant economic benefits to industries in which mineral scaling plagues system performance and long-term durability. This research project will provide outreach activities through public engagement at both George Washington University and University of Maryland. The investigators will host a yearly student-run symposium on environmental nanoscience, and host high school student interns and deliver guest lectures to local high school students. Mineral scaling on surfaces, or the unwanted deposition of mineral precipitates, is a ubiquitous yet unwanted phenomenon in many industrial processes including reverse osmosis, water desalination, heat exchangers, and oil and gas production. One promising strategy for mitigating scaling is to modify polymer surface characteristics or apply polymer coatings to non-polymer surfaces to render the surface scaling resistant. Currently, there is a significant knowledge gap in understanding the nanoscale interactions and physicochemical processes in the initial stages of scale formation on polymers. This knowledge gap limits rational development of scaling-resistant membranes and surface polymer coatings. In this research, the investigators will integrate liquid phase transmission electron microscopy, real-time measurement of scale formation dynamics using quartz crystal microbalance, and theoretical modeling to establish nucleation mechanisms during scaling of silica and gypsum on polyamide surfaces. The research objectives are to 1) investigate the effect of surface charge and hydrophobicity of polyamide films prepared via molecular layer-by-layer assembly on mineral scaling rate, 2) employ liquid phase transmission electron microscopy to visualize and quantify mineral nucleation dynamics on polyamide surfaces in real time at the nanometer length scale and 3) derive theoretical models for nanoparticle attachment and nucleation kinetics to identify the nanoscale interactions involved in scale formation as a function of polymer surface chemistry. The results of this work will facilitate rational manipulation of nanoscale mineral-membrane interactions to prevent mineral scaling on engineering polymers in the aqueous environment. Educational and outreach aspects of the project will incorporate research findings into undergraduate and graduate course materials, host joint student-run nanomaterial and water symposia, and enhance the participation of underrepresented students in research. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.