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/v1

HDPE pellet
TGA, decomposition temperature onset	486 °C
TGA, maximum decomposition temperature	500 °C
TGA, residue	0 wt%
HT-GPC	Mn 21 kDa; Mw 130 kDa; Đ 6.1. Đ is the molar mass dispersity defined by Mw/Mn, evaluated with a cubic fit (R² ≥ 0.999)
CHN elemental analysis	C 86.09 %; H 14.29 %; N 0.03 %

Detergent bottle
TGA, decomposition temperature onset	471 °C
TGA, maximum decomposition temperature	499 °C
TGA, residue	0.4 wt%
HT-GPC	Mn 5.10 kDa; Mw 92.2 kDa; Đ 18. Đ is the molar mass dispersity defined by Mw/Mn, evaluated with a cubic fit (R² ≥ 0.999)
CHN elemental analysis	C 85.82 %; H 14.28 %; N 0.05 %

6-pack holder
TGA, decomposition temperature onset	474 °C
TGA, maximum decomposition temperature	500 °C
TGA, residue	0 wt%
HT-GPC	Mn 10.1 kDa; Mw 120 kDa; Đ 12. Đ is the molar mass dispersity defined by Mw/Mn, evaluated with a cubic fit (R² ≥ 0.999)
CHN elemental analysis	C 86.51 %; H 14.33 %; N 0.05 %

Milk jug
TGA, decomposition temperature onset	462 °C
TGA, maximum decomposition temperature	492 °C
TGA, residue	0 wt%
HT-GPC	Mn 17.1 kDa; Mw 114 kDa; Đ 6.7. Đ is the molar mass dispersity defined by Mw/Mn, evaluated with a cubic fit (R² ≥ 0.999)
CHN elemental analysis	C 89.51 %; H 14.87 %; N 0.02 %

Bleach bottle
TGA, decomposition temperature onset	479 °C
TGA, maximum decomposition temperature	502 °C
TGA, residue	1.2 wt%
HT-GPC	Mn 10.0 kDa; Mw 47.9 kDa; Đ 4.8. Đ is the molar mass dispersity defined by Mw/Mn, evaluated with a cubic fit (R² ≥ 0.999)
CHN elemental analysis	C 86.16 %; H 14.31 %; N 0.02 %

Plastic bag
TGA, decomposition temperature onset	460 °C
TGA, maximum decomposition temperature	488 °C
TGA, residue	12.1 wt%
HT-GPC	Mn 13.0 kDa; Mw 99.5 kDa; Đ 7.6. Đ is the molar mass dispersity defined by Mw/Mn, evaluated with a cubic fit (R² ≥ 0.999)
CHN elemental analysis	C 76.62 %; H 12.54 %; N 0.09 %

PEX-A
TGA, decomposition temperature onset	472 °C
TGA, maximum decomposition temperature	499 °C
TGA, residue	0 wt%
CHN elemental analysis	C 85.98 %; H 14.31 %; N 0.07 %

PEX-B
TGA, decomposition temperature onset	471 °C
TGA, maximum decomposition temperature	500 °C
TGA, residue	1 wt%
CHN elemental analysis	C 85.82 %; H 14.28 %; N 0.04 %

Insoluble polymeric residue following deconstruction of HDPE
HT-GPC, reaction conditions	HDPE (350 mg, Mw 130 kDa), acetic acid (20 mL), O₂ (8 bar), N₂ (72 bar), 160 °C; time inclusive of a ≈ 30 min heating ramp; evaluated with a cubic fit (R² ≥ 0.999)
HT-GPC, 30 min	Mn 4.9 kDa; Mw 12 kDa; Đ 2.5; ~90 % decrease in average Mw
HT-GPC, 60 min	Mn 0.3 kDa; Mw 1.4 kDa; Đ 4.4; ~99 % decrease in Mw

Commercial HDPE pellets and glacial acetic acid before deconstruction
ICP-OES	The metal content in the starting polymer and solvent was found to be negligible, with no significant presence of reactive metal species

Post-autoxidation effluent from titanium and stainless-steel reactors without glass inserts
ICP-OES, reaction conditions	HDPE (350 mg, Mw 130 kDa), acetic acid (20 mL), O₂ (8 bar), N₂ (72 bar), 3 h, 160 °C, in either a 75 mL titanium or stainless-steel Parr reactor; results reported as the mean of triplicate replicates, accompanied by the standard deviation where applicable
ICP-OES	Reactions performed in stainless-steel resulted in the presence of substantial solubilized metal species, one to two orders of magnitude higher than reactions performed in titanium, including soluble iron (>300 ppm), Cr (100 ppm), Mn (8 ppm), and Co (3 ppm), among others

Headspace from catalyst-free HDPE autoxidation
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	Relative to starting-polymer carbon: CO 4.6 ± 1.2 C-mol%; CO₂ 11.4 ± 1.5 C-mol%

Headspace from substrate-free acetic acid autoxidation control
Methanizing GC-FID, reaction conditions	HDPE (0 mg), acetic acid (20 mL), O₂ (8 bar), N₂ (72 bar), 3 h, 160 °C; triplicate measurements
Methanizing GC-FID	<1 C-mol% carbon loss as CO and CO₂ with respect to typical HDPE loadings

HDPE oil analyzed by GPC and UHPLC-TOF-MS
GPC reporting reference	Average carbon number approximated by comparison to C₄, C₁₀, and C₂₀ dicarboxylic acid (DCA) standards
GPC, 1–1.5 h	The average carbon distribution of the soluble fraction was broad, with a mode carbon length ~C₂₀
GPC, 3–5 h	The average carbon length decreased to ~C₁₀ with minimal tailing observed for species above C₂₀
GPC, up to 7 h	No further impact on product distribution
GPC, after further reaction with replenished oxygen	The average carbon length of products decreased to C <10
UHPLC-TOF-MS	Trace species above m/z 450 (C₂₆)

HDPE oil analyzed by NMR
¹H NMR (400 MHz, acetone-d₆), sample	HDPE oil (9.8 mg, 0.64 mmol C) in acetone-d₆ (0.5 mL), charged with maleic anhydride (2.34 mg, 0.0239 mmol) as an internal standard
NMR reporting reference	Referenced to the solvent residuals for acetone-d₆: ¹H 2.05 ppm
¹H NMR (400 MHz, acetone-d₆)	Methyl and methylene peaks produced the highest intensity signal between 0.74–1.69 ppm, followed by α-protons next to a carbonyl between 1.90–2.80 ppm, and lastly α-protons next to a C–O single bond between 3.50–5.00 ppm. Assigned functional groups included carboxylic acids, methyl ketones, γ-ketoacids, γ-lactones, and primary- or secondary-esters, among other unidentified peaks; less than 15 % of peaks were unidentified by peak area
¹H NMR, functional-group contribution	Relative to the total C-mol% of carbonyl peaks identified by ¹H NMR spectroscopy: 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%

HDPE oil analyzed by GC-MS and targeted mass spectrometry
GC-MS	A chromatogram containing series of α,ω₂-oxocarboxylic acids (KAs), free fatty acids (C₁₀–C₃₀), 2-methyl ketones (C₆–C₁₀), and trace β,ω₂-dimethyl diones (C₇–C₁₆), identified by library matches of ≥95 % confidence utilizing the NIST 2020 Mass Spectral Library
Targeted LC-MS and GC-MS	Dicarboxylic acids (DCAs, C₄–C₂₂) comprise 10 C-mol%; α,γ-lactone acids (LCAs, C₅–C₉) and α,ω₂-oxocarboxylic acids (KAs, C₄–C₂₀) were the next most abundant series at 8 and 6 C-mol%, respectively; trace 2-methyl ketones (MKs), β,ω₂-dimethyl diones, and free fatty acids (FFAs) were also quantified

HDPE oil analyzed by FTICR-MS
FTICR-MS (7 T, negative-mode ESI), sample	Dried HDPE oil in methanol (≈10 µg/mL), analyzed in triplicate; initial m/z range 100–1,100
FTICR-MS (7 T, negative-mode ESI), formula annotations	8,042 unique formula annotations present in all 3 technical replicate measurements. Formula constraints: C₁–₁₀₀, H₄–₂₀₀, O₁–₂₃, Na₀–₁, Cl₀–₁, with a ± 0.2 ppm error tolerance
FTICR-MS (7 T, negative-mode ESI), extended range	Signals up to 1,500 m/z were observed upon increasing the ionization range up to 10,000 m/z
FTICR-MS (7 T, negative-mode ESI), visualization filter	Species present in trace quantities, with a signal-to-noise ratio <750, at ≤1.4 % relative to the most intense signal, or with m/z >550 were excluded. After filtering, 727 features represented 95 % of the overall spectrum signal intensity
FTICR-MS (7 T, negative-mode ESI), van Krevelen analysis	Many detected features were species with high saturation and low oxygenation extent
FTICR-MS (7 T, negative-mode ESI), aromaticity criteria	DBE/C >0.7 or AI >0.67 were attributed to species with unambiguous aromatic character. Of the 727 total species, only 10 had DBE/C >0.7 and no species were observed with AI >0.67
FTICR-MS (7 T, negative-mode ESI), composition	Dicarboxylic acids (DCAs) produced the largest signal-to-noise ratio and are likely the dominant products. The range of carbon chain lengths was broad and extended up to C₃₀. The oxygen-atom distribution showed a bias towards even numbers of oxygen atoms in the molecular formula and a maximum at the O₄ stoichiometry

HDPE oil before and after aqueous preparation
HPLC	The HDPE-derived effluent in M9 media prior to bioconversion showed reduced lactone acids as compared to the HDPE-derived oil and an increase in released acetate

M9 media supplemented with deconstructed HDPE before and after RE215 cultivation
21 T FTICR-MS, post-cultivation composition	Data were filtered for signal-to-noise ratios ≥ 1000 and total m/z ≤ 550. Unutilized compounds were present in both non-inoculated and post-RE215 cultivation samples. The 20 molecules with the highest remaining signal intensity and their chemical formula were all relatively large (C ≥ 8) and highly oxygenated (O ≥ 5)