Quantification of Polymer Surface Degradation Using Fluorescence Spectroscopy

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.

Bovine Serum Albumin Bends Over Backward to Interact with Aged Plastics: A Model for Understanding Protein Attachment to Plastic Debris

“…Fit data were used to ascertain fluorescence peak location shift information. Center of mass data (COM) were calculated using both fit data and raw data with no deviation in COM calculations for any of the data sets reported . Second derivative analysis was independently performed on postcollect data smoothed with a sixth order Saviztky-Golay (SG) filter with data initially smoothed followed by a sequential numerical gradient.…”

“…Center of mass data (COM) were calculated using both fit data and raw data with no deviation in COM calculations for any of the data sets reported. 46 Second derivative analysis was independently performed on postcollect data smoothed with a sixth order Saviztky-Golay (SG) filter with data initially smoothed followed by a sequential numerical gradient. SG and 2-Gaussian filter results were compared and showed no significant deviation between techniques.…”

Novel Hybrid Gel–Fiber Membranes as Carriers for Lipase Catalysis Based on Electrospinning and Gelation Technology

“…By comparing the size of the angle at the moment of contact, it is possible to understand the wettability of the material in the medium [30,31]. The larger the contact angle, the weaker the wettability [32].…”

Small microplastic particles in Lake Superior: A preliminary study coupling Nile red staining, flow cytometry and pyrolysis gas chromatography–mass spectrometry

“…While this study sorted all NR positive particles as plastic, the use of different fluorescence and size characteristics within a natural particle sample as sorting criteria could further separate plastics from other types of particles. It could also enable sorting focused on specific plastic polymers or polymer aging characteristics, based upon differing fluorescence characteristics (Maes et al 2017;Tigner et al 2023); these chemical features could then be confirmed by PyGCMS or microRaman. Forward and side scatter in FCM could be used to isolate specific particle morphologies, confirmed with fluorescence microscopy.…”