Stage-Specific Polymerization Mechanisms in Bio-Tar Unveiled by Single-Functional Model-Compounds: Dominant Roles of Unsaturated Oxygen Moieties

Yuxuan SUN; Lixin ZHAO; Huiyan ZHANG; Hui ZHOU; Lili HUO; Jixiu JIA; Zonglu YAO

doi:10.1016/j.eng.2026.02.034

Engineering ›› :202602034 DOI: 10.1016/j.eng.2026.02.034

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Stage-Specific Polymerization Mechanisms in Bio-Tar Unveiled by Single-Functional Model-Compounds: Dominant Roles of Unsaturated Oxygen Moieties

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Abstract

Bio-tar, a byproduct of biomass pyrolysis, poses environmental and processing challenges owing to its tendency to clog pipelines and its ecotoxicity. Converting bio-tar into functional carbon materials offers a sustainable route for waste valorization; however, the underlying thermal polymerization mechanisms remain poorly understood. Herein, we present a single-functional model-compound-assisted analytical strategy to elucidate reaction pathways and polymerization mechanisms in multifunctional group coupling systems. By constructing a model bio-tar (M-bio-tar) that reflects the chemical heterogeneity of real samples, we uncover a temperature-dependent, stage-specific polymerization mechanism comprising volatile release ( ≤ 200 °C), radical-driven crosslinking polymerization (200–400 °C), and carbon skeleton consolidation ( ≥ 300 °C). Radical dynamics involving alkyl and hydroxyl radicals (R^• and HO^•) are key contributors to crosslinking processes, while oxygenated intermediates, such as aldehydes and furans, enhance polymerization efficiency via synergistic Diels–Alder and cyclization reactions. Structural evolution analyses reveal temperature-dependent trade-offs among graphitization, dehydrogenation, and porosity development. Temperature-mediated graphitization and heteroatom elimination result in bio-carbons with tunable physicochemical properties. Thermodynamic calculations support the proposed oxygen-regulated reaction pathways and reveal the catalytic roles of unsaturated functionalities. These findings establish a mechanistic framework for engineering bio-tar-derived carbon materials that integrates biomass utilization and advanced material design, thereby advancing the rational development of sustainable carbon materials for energy and environmental applications within a circular bioeconomy.

Keywords

Bio-tar / Bio-carbon / Polymerization / Model compound / Simulation

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Yuxuan SUN, Lixin ZHAO, Huiyan ZHANG, Hui ZHOU, Lili HUO, Jixiu JIA, Zonglu YAO. Stage-Specific Polymerization Mechanisms in Bio-Tar Unveiled by Single-Functional Model-Compounds: Dominant Roles of Unsaturated Oxygen Moieties. Engineering 202602034 DOI:10.1016/j.eng.2026.02.034

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