The dominant role of N-containing side chains in peptide-mediated graphene dispersion and stabilization: a molecular...

Graphene exhibits exceptional physical properties, yet its strong interlayer van der Waals interactions and hydrophobic nature lead to severe aggregation in aqueous environments, limiting scalable processing. While peptide-assisted dispersion offers a promising green strategy, the molecular mechanisms linking peptide structure to dispersion efficiency remain unclear. Here, all-atom molecular dynamics simulations selected homo-peptides polymerized from a single amino acid to investigate the role of peptide side-chain chemistry in regulating graphene dispersion systematically. Ten representative peptides with distinct side-chain structures were examined by analyzing water intercalation behavior, interlayer solvent-layer stability, and graphene re-aggregation dynamics. Radial distribution functions, graphene normal-vector evolution, and peptide density distributions were used to resolve interfacial interactions at the molecular scale. The results reveal that graphene dispersion is governed by a synergistic "anchoring-attraction" mechanism. N-containing peptides simultaneously achieve strong surface anchoring and effective hydration, which promote water intercalation, stabilize interlayer solvent layers, and suppress re-aggregation. In contrast, non-N-containing peptides fail to achieve efficient dispersion due to a deficiency in either anchoring (e.g., negatively charged carboxyl peptides) or attraction (e.g., hydrophobic alkyl peptides). Among the N-containing structures, positively charged side-chains exhibit the highest dispersion efficiency. Moreover, dispersion performance increases with polymerization degree and concentration within an optimal range, beyond which chain entanglement or self-aggregation deteriorates stability. This work establishes a clear structure-interfacial behavior-dispersion relationship, providing molecular-level guidance for designing efficient and environmentally benign graphene dispersants centered on N-containing structural motifs.