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

Abstract

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.