Self-Assembled Monolayers (SAM) as a Model for Photooxidation of Plastic Waste Using ATR-FTIR and Kinetic Modelling

Name: Jenelle C. Booker
Major: Chemistry
Minor: Environmental Studies and German
Advisors: Karl J. Feierabend and Paul L. Edmiston
As of 2017, 8.3 billion metric tons of plastic exist world wide, and with their long lifetimes, will become chemically integrated into our environment. In order to understand the long-term impacts of plastic waste on human and wildlife health, this project sets the foundations for both a laboratory and kinetic model of plastic degradation, in particular plastic photo-oxidation. Assuming degradation occurs on the outermost surface of a plastic, photo-oxidation can be modelled using a singular layer of hydrocarbons—the chemical backbone of most plastics. This singular layer was created using a self-assembled monolayer (SAM) of chloro(dimethyl)octadecylsilane (CH3(CH2)17Si(CH3)2Cl) and was reacted with UV-C light and environmentally relevant concentrations of water vapor, oxygen, and ozone. To track photo-oxidation in realtime and to avoid disruption of the plastic monolayer, the SAM was formed on an attenuated total reflectance (ATR) germanium crystal, through which IR analysis could occur. In conjunction with ATR-IR analysis, a kinetic model was created to investigate the gas and photo-chemistry of the experimental set up, in particular the formation of hydroxyl free radicals–the key initiator in plastic photo-oxidation. By simulating plastic photo-oxidation in the lab, and therefore, determining the dominant products and mechanisms, the chemical impact of plastic waste can be explored quickly and at a lower cost than field sampling. This project is therefore instrumental in informing the environmental community the enduring effects of plastic waste on our natural environment.

Jenelle will be online to field comments on April 16:
10am-noon EDT (Asia: late evening, PST: 6-8am, Africa/Europe: early evening)

Posted in I.S. Symposium 2021, Independent Study on April 10, 2021.