The behaviour of polymer colloids in freshwater flow environment

The monitoring of the presence of microplastics in the environment (water, soil, organisms) has gained considerable traction, with a plethora of initiatives. The presence of plastic particles can enter the food chain for all living species, with potential negative impacts.

In this project, we will look at particles in the diameter range of 20 nm - 5 micrometers; in other words, a focus on the sub-micron range, plastic nanoparticles. In nature, these exist as a natural polymer latex (rubber trees, dandelions). Synthetic polymer nanoparticles, in the form of polymer dispersions, are produced in vast quantities since the 1930s for coatings/adhesives, paper production, medical diagnostic tests, to name but a few.

We aim to fabricate a collection of model polymer dispersions in which the particles have varied size, shape, molecular weight and chemical composition, and colloidal stability characteristics. We will both look at particles that do not degrade quickly, and ones that are compostable/hydrolysable. We will use the latest polymer dispersion production techniques, such as emulsion polymerization, and catastrophic phase inversion emulsification.

We then will study the underlying physical mechanisms that govern the particles' motility behavior (flow hydrodynamics, dispersion, and diffusion) and residence and accumulation behavior (adhesion, crowding, coagulation, film formation, disintegration/decomposition) in model aquatic systems. Tracking methods of the particles in water and model soils will be developed through darkfield, Raman, and fluorescence microscopy, as well as off-line analysis methods, such as hydrodynamic fractionation and elemental analysis techniques.

This project, for the first time, will provide a better understanding of how such small particles will behave across aquatic domains, where they will reside, and how they potentially can be degraded into harmless substituents.