Laboratory Synthesis, Characterization, and Py-GCMS-Based ¹³C Quantification of ¹³C‑Enriched Polyethylene

Labeling polymers with ¹³C isotopes enables precise tracking of carbon during chemical transformations and biodegradation, offering valuable insights into degradation mechanisms and the environmental impact. Nevertheless, the commercial availability of such labeled polymers remains limited. This is primarily due to the lack of ¹³C-labeled monomers required for synthesizing the corresponding polymers and the high costs associated with their production. These challenges hinder the widespread application of ¹³C-labeled polymers in research and industry. In this study, we report the successful laboratory synthesis and characterization of ¹³C stable isotope-enriched polyethylene. Homopolyethylene and copolyethylene samples with an approximate 25 wt % ¹³C-enrichment were produced by polymerizing mixtures of standard and ¹³C isotope-labeled ethylene monomers. The characterization of the ¹³C-labeled polyethylene samples indicated that their microstructural properties were similar to those of the standard polyethylene samples produced from conventional ethylene monomers. Additionally, we present the quantification of ¹³C isotope enrichment in polyethylene using pyrolysis gas chromatography-mass spectrometry (Py-GCMS), alongside conventional nuclear magnetic resonance (NMR) and isotope ratio mass spectrometry (IRMS) analysis. Our results demonstrate that the ¹³C isotope enrichment values measured by Py-GCMS are comparable to those obtained from the conventional IRMS method, indicating the potential application of Py-GCMS as an alternative method for ¹³C isotope analysis in polymer samples.