CAREER: Unraveling nanoplastic release from nanoscale mechanical degradation: Enabling sustainable design of polymers and defining future engineer

About This Grant

The accumulation of plastics in the environment is an urgent and critical problem. Plastics break down into micro- and nanoplastics, which readily infiltrate environmental media and biological tissues. They are found globally in natural environments and in many parts of the human body. However, they can be difficult to detect in real-world samples. This project will focus on a new mechanism for assessing how nanoplastics are released from bulk plastics. During and after their useful lifetime, plastics often slide over surfaces and collide with surfaces. For example, plastic litter slides over land surfaces driven by wind or stormwater. Plastics in moving sediments or agricultural soil collide repeatedly with hard surfaces. The project will use an experimental technique called atomic force microscopy to visualize on the nanoscale the deformation, abrasion and release of nanoplastics under conditions that simulate environmental circumstances. Factors that can influence nanoparticle release will be studied, including abrasion conditions, plastic properties, and pre-exposure of the plastic to sunlight. The research will be integrated with educational activities to broaden participation in STEM among K6-12 students. The team will partner with high schools in the Twin Cities school districts to develop novel research curricula that investigate weathering of plastic goods that general micro- and nanoparticles. The project will leverage the Industrial Partnership for Research in Interfacial and Materials Engineering platform to organize workshops for industrial experts, academics, and Minnesota policymakers to share knowledge, identify collaborations, and discuss knowledge gaps toward risk assessment and sustainable design of plastics Microplastics and nanoplastics are ubiquitous and have significant impacts on human health and ecosystem functions. Micro- and nanoplastics are primarily derived from the breakdown of plastics in natural and engineered systems. To inform risk and mitigation, it is critical to identify sources, release mechanisms, and rates of nanoplastic release from bulk plastic degradation during natural weathering. This project focuses on a less explored mechanism - surface abrasive wear at the nanoscale. Abrasive wear results from the penetration of a harder particle and/or protruding surface (i.e., asperity) into the softer plastic surface, causing plastic deformation and potentially debris removal in sliding contact. The central hypothesis is that plastics sliding over a surface with nanoroughness creates nanoscale wear and the release of nanometer-size debris. The project leverages the novel single-asperity nanoscratch method and other advanced atomic force microscopy modes to visualize the mechanism of nanoplastic generation and release from abrasive wear and to identify key physicochemical properties of nanoplastics that result in health impacts. Results will reveal how and why different abrasion conditions, plastic properties, and pre-exposure to sunlight shape the nanoplastic release profile, which can enable risk assessment and screening tools for the design of sustainable polymers. Engagement and networking with industry will accelerate the discovery of possible solutions to mitigate nanoplastic pollution. 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.