Linking molecular antioxidant activity to polyurethane foam stability – the case of Abies marocana essential oil
Scientific Reports (2026)
Abstract
In this work, compounds from Abies marocana essential oil (AMEO) were studied for their antioxidant potential using density functional theory (DFT) calculations at the M06-2X/6-311 + G(d,p) level of theory. The antioxidant activity was evaluated through three mechanistic pathways: hydrogen atom transfer (HAT), single electron transfer–proton transfer (SET-PT), and sequential proton loss–electron transfer (SPLET). The corresponding thermodynamic descriptors, including bond dissociation enthalpy (BDE), ionization potential (IP), proton dissociation enthalpy (PDE), proton affinity (PA), and electron transfer enthalpy (ETE), were calculated in the gas phase, while the HAT mechanism was additionally investigated in water and ethylene glycol to assess solvent effects. Additionally, frontier molecular orbital (FMO) analysis revealed that α-pinene possesses the smallest HOMO-LUMO energy gap (Eg), followed by limonene, further supporting the higher chemical reactivity and radical scavenging potential of these compounds. The influence of the studied essential oil as a natural antioxidant additive at varying concentrations on the thermal degradation (ageing) of flexible polyurethane foams was also assessed. Compression tests before and after dry heat ageing indicated that AMEO-modified foams showed improved compression-force retention compared with the reference sample. Higher AMEO concentrations increased the absolute compression force before and after ageing, while the calculated percentage compression-force loss was generally lower than that of the reference sample, indicating improved ageing resistance. Fourier transform infrared spectroscopy (FTIR) analysis suggested that AMEO does not form strong chemical interactions with the polyurethane matrix, supporting a physical radical scavenging mechanism. These results suggest that AMEO can serve as a multifunctional additive in polyurethane foams, providing both antioxidant activity and mechanical property tuning.
Acknowledgements
This research was supported by the Centre National de la Recherche Scientifique et Technique (CNRST) through the PhD-Associate Scholarship – PASS program in Morocco. Additional support was provided by the University Research Scholarship Program of the Ministry for Culture and Innovation, funded by the National Research, Development and Innovation Fund. BF thanks the support by the János Bolyai Research Scholarship of the Hungarian Academy of Sciences. We acknowledge the Digital Government Development and Project Management Ltd. for awarding us access to the Komondor HPC facility based in Hungary. Calculations have also been carried out using resources provided by Wroclaw Centre for Networking and Supercomputing (http://wcss.pl).
Funding
Open access funding provided by University of Miskolc. This work was funded by the Centre National de la Recherche Scientifique et Technique (CNRST) under the PhD-Associate Scholarship – PASS program (Morocco). Furthermore, DM and RB thanks the University Research Scholarship Program of the Ministry for Culture and Innovation (Hungary), supported by the National Research, Development and Innovation Fund. BF thanks the support by the János Bolyai Research Scholarship of the Hungarian Academy of Sciences.
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