Carbonization refers to the conversion of organic networks into carbon-rich materials via a sequence of heat-activated reactions, but the underlying mechanism remains a mystery. Here, we conduct a systematic atomic-scale investigation of complex chemical reactions and structural evolution during carbonization via reactive force field molecular dynamics simulations. Three representative precursors, including phenolic resin, furfuryl alcohol resin, and naphthalene-derived mesophase pitch, are selected to clarify how molecular architecture regulates the carbonization pathway. All precursors follow a multistage carbonization mechanism involving ring opening, gas evolution, cyclization/rearrangement, and aromatization. Specifically, the aromaticity and heteroatom content of the precursors govern carbonization yield (49–72%), and ring structure stability, thereby yielding carbon products with distinct sp2-hybridized ratios (84–95%). Furthermore, graphitization at elevated temperatures involves carbon cluster rearrangement driven by sp3-sp2 rehybridization and layer stacking mediated by van der Waals interactions. This rearrangement and interlayer stacking induce pronounced anisotropy in the graphitic structure, which consequently leads to substantial variations in thermal conductivity. These findings provide atomistic insights into carbonization and graphitization mechanisms, which may offer meaningful guidance for the design and preparation of high-performance carbon materials.
Li et al. (2026) studied this question.