Quantification of Polymer Surface Degradation Using Fluorescence Spectroscopy

Jonathan M. Tigner, Margaret M Elmer-Dixon, Melissa A. Maurer-Jones

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

One solution to minimizing plastic pollution is to improve reuse and recycling strategies. Recycling, however, is limited by the overall degradation of plastics being used, and current techniques for monitoring this plastic degradation fail to observe this in its early stages, which is key for optimizing reusability. This research seeks to develop an inexpensive, reproducible, and nondestructive technique for monitoring degradation of polyethylene (PE) and polypropylene (PP) materials using Nile red as a fluorescent probe. Changes in Nile red’s fluorescence spectra were observed upon exposure to stained, aged PE and PP samples. As the surface hydrophobicity of the plastic decreases, Nile red’s fluorescence signal undergoes a corresponding signal shift to longer wavelengths (lower energy). The trends seen in the fluorescent profile were related to more commonly used measurements of plastic degradation, namely, the carbonyl index from infrared spectroscopy and bulk crystallinity from calorimetry. Results demonstrate clear trends in fluorescence spectra shifts as related to the chemical and physical changes to the plastics, with trends dependent on the polymer type but independent of polymer film thickness. The strength of this technique is divided into two defined fits of the fluorescence signal; one fit characterizes the degradation throughout the whole range of degradative oxidation and the other is tailored to provide insight into the early stages of degradation. Overall, this work establishes a characterization tool that assesses the extent of plastics’ degradation, which may ultimately impact our ability to recover plastics and minimize plastic waste.

Original languageEnglish (US)
Pages (from-to)9975-9982
Number of pages8
JournalAnalytical Chemistry
Volume95
Issue number26
DOIs
StatePublished - Jul 4 2023

Bibliographical note

Funding Information:
The authors acknowledge Daniel Zoltek for the preparation and FTIR characterization of thermally degraded polymers. Further, we thank the UMD Department of Chemistry and Biochemistry for the use of their fluorescence spectrophotometer and FTIR. UMD provided funding for this work both to J.M.T. from the Department of Chemistry and Biochemistry at UMD in the form of a teaching assistantship and M.A.M.-J. as part of her startup funds. M.M.E.-D. was supported by the University of Minnesota McKnight Foundation. Lastly, the table of contents figure was made using Bio Render.

Publisher Copyright:
© 2023 American Chemical Society

PubMed: MeSH publication types

  • Journal Article

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