S-S Vitrimer Composites via Simplified Fabrication: Recyclable Graphite Flakes Simultaneously Enhance Mechanical-Thermal Properties and Suppress Disulfide Exchange

Vitrimers are covalently crosslinked networks with dynamic bond exchange, where their dynamic behavior is typically regulated by adjusting network structures or incorporating fillers. This study introduces graphite flakes (GFs) into sulfur-containing. Vitrimers to investigate their effects on mechanical properties, stress relaxation, and thermal conductivity. The results demonstrate that adding 10 wt.% GFs increases tensile strength by 4.37% compared to pure epoxy vitrimer, while higher filler content reduces toughness and decelerates stress relaxation. At 160 °C, the characteristic relaxation time rises from 15.35 s (pure vitrimer) to 108.85 s (40 wt% GFs composite). The Arrhenius prefactor ( τ₀ ) decreases with GFs loading, whereas the activation energy ( E a ) remains nearly unaffected. Additionally, 40 wt.% GFs enhance thermal diffusivity by 110.17% due to oriented phonon transport channels. Chemical recycling via DTT solution achieves complete matrix degradation and filler recovery without damaging GFs. This study provided valuable insights for optimizing vitrimer composites, particularly in enhancing thermal conductivity and modulating dynamic properties.