From Molecular Interactions to Mechanical Behavior: Probing Lignin/Sodium Alginate Composites via Molecular Dynamics Simulations

The application of sodium alginate (SA) in textile fibers is restricted due to its random sequence of monomer units within the molecular structure and its low crystallinity, which cause unsatisfactory mechanical properties. Although lignin is a potential reinforcing filler for SA-based composites, the interfacial interactions between lignin and SA remain unclear. In this study, molecular dynamics (MD) simulations were used to explore the interaction mechanism. Four SA-based composite models with lignin concentrations of 0, 4, 7, and 11% were constructed to analyze molecular interactions, as well as mechanical and thermal properties. MD theoretical predictions showed that hydrogen bonds between lignin and SA were crucial for enhancing interfacial interactions. The composite with 4% lignin exhibited the best mechanical and thermal performance, indicating optimal compatibility. This research provides a basis for developing strong, sustainable SA-based textile fibers reinforced with lignin.