Intercalation of chitosan into montmorillonite nanocomposites with experimental and molecular dynamics study toward sustainable functional materials

Abstract

The growing demand for sustainable and functional nanocomposites in biomedicine and environmental remediation motivates this study on the structural and thermal evolution of chitosan–montmorillonite systems. Using a combined experimental–computational approach, nanocomposites were synthesized at pH = 4.1 with varying chitosan-to-clay ratios and systematically characterized. X-ray diffraction revealed an expansion of basal spacing from 12.0 Å (pure montmorillonite) to 20.3 Å at the highest chitosan content, aligning with theoretical predictions (19.18 Å) for monolayer and bilayer intercalation. FTIR spectra confirmed strong hydrogen bonding and electrostatic interactions between chitosan and clay layers. Thermogravimetric analysis indicated a slight decrease in decomposition temperature (198 → 182–186°C) but improved overall thermal stability, evidenced by reduced mass loss and higher residual content. Molecular dynamics simulations further elucidated intercalation mechanisms, with a 5.06% theoretical deviation for bilayer formation and RDF peaks at 1 Å (53.4 Å for monolayer and 68.7 Å for bilayer), highlighting stabilizing molecular forces. These findings establish a predictive framework for tailoring chitosan–montmorillonite nanocomposites with enhanced structural and thermal performance, underscoring their promise for sustainable applications such as food packaging and edible films.