Collaborative Research: CAS: Understanding Polymer Additive Release and Transformations in Aquatic Environments

Colorado School Of Mines, Golden CO

Investigators

Abstract

This award from the Environmental Chemical Sciences Program of the Division of Chemistry funds a collaborative project by Professor James Ranville at the Colorado School of Mines and Professor Howard Fairbrother at the University of Maryland. The team studies what happens to additives in plastics as the plastics slowly decay in the environment. Complex chemical compounds are added the during manufacturing of plastics to improve their properties, such as durability, color and texture. The chemical composition of these additives is very varied and can include small organic molecules as well as metal-containing organic compounds. The accumulation of plastic waste in aquatic environments is a highly visible problem of increasing global concern. When plastics are in contact with water or exposed to sunlight, the chemical additives are slowly released into the water. There they can undergo chemical transformation to form new compounds. Unfortunately, a number of additives and their transformation products have been found to pose a risk to the environment and to human health. Information from this study can help improve our understanding of the science to guide the design of new additives with reduced environmental impacts. The students involved in this research acquire skills in materials chemistry and environmental science. Students at the K-12 and university level participate in educational activities, such as hands-on experiences with end-of-life issues with plastics. The project aims to develop a molecular level understanding of how the chemical composition and physical characteristics of additives in polymers influence the release and subsequent photochemical transformations of additives in aqueous environments. These goals are accomplished by measuring additive release kinetics and sorption properties from a selected set of well characterized additive/polymer composites. This is complemented by measurements of phototransformation kinetics and transformation products using a suite of highly sensitive mass spectrometry techniques. Model organic and organometallic compounds are used to test hypotheses and develop structure activity relationships related to additive release and photochemical transformations. These models address the role of molecular level properties of additives, polymer-additive interactions, and changes in polymer surface properties in determining the behavior of additives in aqueous environments. The results can be extrapolated to a wide range of additive/polymer combinations relevant to plastic pollution in the aquatic environment. 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.