Interfacial Phenomena of Plastics: From Surface Modifications to Environmental Impacts

Plastic is a ubiquitous part of everyday life since its introduction in the previous century. Global production continues to exponentially increase, establishing plastics as one of the most dominant materials in modern manufacturing. Within the scope of academia, plastic is essential due to its low cost and sterility, particularly for minimizing contamination. Beyond the laboratory, plastic use spans numerous industries, and its use and disposal has since raised many environmental concerns. Once valued for its durability, plastics now pollute the environment in landfills and natural ecosystems. In recent decades, the consequences of this pollution have been investigated, yet the full impact is not fully understood. This Ph.D. dissertation examines three distinct aspects of plastic research from a colloidal perspective. First, we explore the use of plastic beads in colloidal science by synthesizing novel patchy particles and investigating their self-assembly behavior. By fine-tuning particle-solvent interactions, we selectively corrugate the particle surface while preserving its chemical composition. This allows us to isolate the impact of partial surface roughness and investigate its role in depletion-driven self-assembly. Next, we shift towards environmental remediation, introducing thermoresponsive foams to separate microplastics from solution. Conventional microplastic separation methods rely on compatible surface properties, which are not always consistent following disposal. Our approach utilizes the assembly of fatty acid into microtubules which trap microplastics in a foam. We present the results for our model system and for plastics that have undergone surface alterations due to aging, to reassure the process presented herein is dependent only on the physical properties of the microplastics. Finally, we investigate the changes in bacterial colonization to plastic surfaces. v Alcanivorax borkumensis, a known hydrocarbonoclastic bacteria, has been previously studied as a candidate for low-density polyethylene degradation. We examine how preconditioning the bacteria to different-length alkanes influences bacterial attachment and surface modifications on polyethylene. This leads to distinct adhesion behaviors and surface oxidation on the plastic, driven by bacterial colonization. Together, these studies contribute to a deeper understanding of plastic behavior in colloidal systems, its role in environmental pollution as well as potential remediation strategies.