Compound characterization data — Frey et al., 2026

Brandon L. Frey, Ross Eaglesfield, Ciaran W. Lahive, Jeremy R. Bussard, Ali Chamas, Stephen H. Dempsey, Keven D. Dooley, Morgan A. Ingraham, Rui Katahira, William Kew, Jiyeong Kim, Spencer Lask, Clarissa Lincoln, William E. Michener, Joel Miscall, Kelsey J. Ramirez, Anna N. Walsh, Dylan J. Walsh, Jungki Ryu, Shannon S. Stahl, Allison Z. Werner, Gregg T. Beckham. “Polyethylene conversion to mevalonate via catalyst-free autoxidation and bioconversion.” ChemRxiv (2026). https://doi.org/10.26434/chemrxiv.15007716/v2

A standalone carbon-recovery result was not retained

HDPE pellet
TGA	Td, onset: 486 °C; Td, max: 500 °C; Residue: 0 wt%
HT-GPC (cubic fit, R² ≥ 0.999)	Mn: 21 kDa; Mw: 130 kDa; Đ: 6.1
CHN elemental analysis	C, 86.09 %; H, 14.29 %; N, 0.03 %

Post-consumer detergent bottle substrate
TGA	Td, onset: 471 °C; Td, max: 499 °C; Residue: 0.4 wt%
HT-GPC (cubic fit, R² ≥ 0.999)	Mn: 5.10 kDa; Mw: 92.2 kDa; Đ: 18
CHN elemental analysis	C, 85.82 %; H, 14.28 %; N, 0.05 %
TGA, FTIR and HT-GPC plots	Image data were not transcribed

Post-consumer 6-pack holder substrate
TGA	Td, onset: 474 °C; Td, max: 500 °C; Residue: 0 wt%
HT-GPC (cubic fit, R² ≥ 0.999)	Mn: 10.1 kDa; Mw: 120 kDa; Đ: 12
CHN elemental analysis	C, 86.51 %; H, 14.33 %; N, 0.05 %
TGA, FTIR and HT-GPC plots	Image data were not transcribed

Post-consumer milk jug substrate
TGA	Td, onset: 462 °C; Td, max: 492 °C; Residue: 0 wt%
HT-GPC (cubic fit, R² ≥ 0.999)	Mn: 17.1 kDa; Mw: 114 kDa; Đ: 6.7
CHN elemental analysis	C, 89.51 %; H, 14.87 %; N, 0.02 %
TGA, FTIR and HT-GPC plots	Image data were not transcribed

Post-consumer bleach bottle substrate
TGA	Td, onset: 479 °C; Td, max: 502 °C; Residue: 1.2 wt%
HT-GPC (cubic fit, R² ≥ 0.999)	Mn: 10.0 kDa; Mw: 47.9 kDa; Đ: 4.8
CHN elemental analysis	C, 86.16 %; H, 14.31 %; N, 0.02 %
TGA, FTIR and HT-GPC plots	Image data were not transcribed

Post-consumer plastic bag substrate
TGA	Td, onset: 460 °C; Td, max: 488 °C; Residue: 12.1 wt%
HT-GPC (cubic fit, R² ≥ 0.999)	Mn: 13.0 kDa; Mw: 99.5 kDa; Đ: 7.6
CHN elemental analysis	C, 76.62 %; H, 12.54 %; N, 0.09 %
TGA, FTIR and HT-GPC plots	Image data were not transcribed

Post-consumer PEX-A substrate
TGA	Td, onset: 472 °C; Td, max: 499 °C; Residue: 0 wt%
HT-GPC (cubic fit, R² ≥ 0.999)	Not determined due to partial insolubility in trichlorobenzene, due to crosslinking, resulting in low signal and likely underrepresented values
CHN elemental analysis	C, 85.98 %; H, 14.31 %; N, 0.07 %
TGA, FTIR and HT-GPC plots	Image data were not transcribed

Post-consumer PEX-B substrate
TGA	Td, onset: 471 °C; Td, max: 500 °C; Residue: 1 wt%
HT-GPC (cubic fit, R² ≥ 0.999)	Not determined due to partial insolubility in trichlorobenzene, due to crosslinking, resulting in low signal and likely underrepresented values
CHN elemental analysis	C, 85.82 %; H, 14.28 %; N, 0.04 %
TGA, FTIR and HT-GPC plots	Image data were not transcribed

Insoluble polymeric residue from HDPE deconstruction
HT-GPC (HDPE 350 mg, acetic acid 20 mL, O₂ 8 bar, N₂ 72 bar, 160 °C; 30 min; cubic fit, R² ≥ 0.999)	Mn: 4.9 kDa; Mw: 12 kDa; Đ: 2.5
HT-GPC (HDPE 350 mg, acetic acid 20 mL, O₂ 8 bar, N₂ 72 bar, 160 °C; 60 min; cubic fit, R² ≥ 0.999)	Mn: 0.3 kDa; Mw: 1.4 kDa; Đ: 4.4
HT-GPC chromatograms	Image data were not transcribed

HDPE autoxidation headspace
Methanizing GC-FID, reaction conditions	HDPE (350 mg, Mw 130 kDa), acetic acid (20 mL), O₂ (8 bar), N₂ (72 bar), 3 h, 160 °C; triplicate measurements
Methanizing GC-FID headspace analysis	Relative to starting-polymer carbon: CO: 4.6 ± 1.2 C-mol%; CO₂: 11.4 ± 1.5 C-mol%
Methanizing GC-FID plots	Image data were not transcribed

HDPE oil
¹H NMR (400 MHz, acetone-d₆)	Methyl and methylene peaks: 0.74–1.69 ppm; α-protons next to a carbonyl: 1.90–2.80 ppm; α-protons next to a C–O single bond: 3.50–5.00 ppm
¹H NMR, functional-group assignments	Carboxylic acids: 48 C-mol%; methyl ketones: 20 C-mol%; γ-ketoacids: 10 C-mol%; γ-lactones and primary and secondary ester products combined: 21 C-mol%; less than 15 % of peaks were unidentified by peak area
GC–MS	Ketoacids (C₄–C₂₀), free fatty acids (C₁₀–C₃₀), 2-methyl ketones (C₆–C₁₀) and trace β,ω-2-dimethyl diones (C₇–C₁₆) were identified by library matches of ≥95 % confidence using the NIST 2020 Mass Spectral Library
LC–MS and GC–MS quantification	Relative to starting-polymer carbon: dicarboxylic acids (C₄–C₂₂): 10 C-mol%; lactone carboxylic acids (C₅–C₉): 8 C-mol%; ketoacids (C₄–C₂₀): 6 C-mol%; total quantified soluble carbon yield: 26 C-mol%; the remaining 54 % C-mol% was unidentified miscellaneous oxygenates, calculated via the CHN total minus the sum of the quantified species
GPC, carbon-number distribution	Mode near C₂₀ after 1–1.5 h; mode near C₁₀ after 3–5 h; no further impact on product distribution through 7 h; C<10 after resubjection to reaction with replenished oxygen
UHPLC–TOF–MS	Trace species above m/z 450 (C₂₆)
FTICR–MS (negative-mode ESI, 7 T)	8,042 unique formula annotations were present in all three technical replicate measurements over m/z 100–1,100; signals up to m/z 1,500 were observed when the ionization range was increased to m/z 10,000; after filtering, 727 features represented 95 % of the overall spectrum signal intensity
FTICR–MS, DBE/C and aromaticity index	Of the 727 filtered species, 10 had DBE/C > 0.7 and none had an aromaticity index > 0.67
NMR spectra, chromatograms and mass spectra	Image data were not transcribed

HDPE deconstruction samples
CHN, ICP-OES, LC–MS/MS, GC-FID and HT-GPC plots	Image data were not transcribed