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

Area of Science:

• Polymer Chemistry
• Isotope Labeling
• Materials Science

Background:

• Polymers labeled with Carbon-13 (13C) isotopes are crucial for tracking carbon during chemical transformations and biodegradation.
• Limited commercial availability of 13C-labeled polymers hinders research due to the scarcity and high cost of 13C-labeled monomers.
• This limitation restricts the widespread use of 13C-labeled polymers in scientific and industrial applications.

Purpose of the Study:

• To report the laboratory synthesis and characterization of 13C stable isotope-enriched polyethylene.
• To demonstrate a method for quantifying 13C isotope enrichment in polyethylene.
• To evaluate pyrolysis gas chromatography-mass spectrometry (Py-GCMS) as an alternative analytical technique for 13C isotope analysis in polymers.

Main Methods:

• Synthesis of homopolyethylene and copolyethylene with approximately 25 wt% 13C-enrichment via polymerization of mixed standard and 13C-labeled ethylene monomers.
• Characterization of synthesized 13C-labeled polyethylene for microstructural properties.
• Quantification of 13C isotope enrichment using pyrolysis gas chromatography-mass spectrometry (Py-GCMS), nuclear magnetic resonance (NMR), and isotope ratio mass spectrometry (IRMS).

Main Results:

• Successfully synthesized 13C-enriched polyethylene with comparable microstructural properties to standard polyethylene.
• Demonstrated that Py-GCMS can quantify 13C isotope enrichment in polyethylene.
• 13C isotope enrichment values measured by Py-GCMS were comparable to those obtained by the conventional IRMS method.

Conclusions:

• The laboratory synthesis of 13C-enriched polyethylene was successful, addressing the limited availability of labeled polymers.
• The microstructural properties of the synthesized 13C-labeled polyethylene are similar to conventional polyethylene.
• Py-GCMS shows potential as a viable alternative method for analyzing 13C isotope enrichment in polymer samples.