Comparison of the Physicochemical Properties of Coated and Intercalated Chitosan–Clay Systems: an Inverse Gas Chromatography Approach

ABSTRACT This study aims to investigate the surface and interfacial physicochemical properties of chitosan (CS)‐coated bentonite (CSBt) and CS‐intercalated Na + ‐montmorillonite biocomposites (CSMMT). The structural and surface characteristics of these two CS‐based biocomposites were analyzed using thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy, nitrogen adsorption, X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), and inverse gas chromatography at infinite dilution (IGC‐ID) as well as finite concentration conditions (IGC‐FC). XRD analysis revealed that CS was intercalated into the nanostructure of CSMMT biocomposites, a phenomenon not observed in CSBt biocomposites. XPS indicated that the CSMMT biocomposites possessed MMT‐rich surface, whereas CSBt biocomposites exhibited CS‐rich surface. IGC‐ID measurements showed that the dispersive components of the surface energy, , was higher for CSMMT biocomposites compared with CSBt. This increase is attributed to the preserved interlayered structure and the availability of high‐energy surface sites on CSMMT surface, while the CS coating on CSBt biocomposites masked these high‐energy adsorption sites. IGC‐FC analysis using isopropanol as a probe revealed that the distribution function remained bimodal for CSMMT biocomposites but became monomodal and symmetrical for CSBt biocomposites. This observation suggests the disappearance of high‐energy sites and confirms the coating of the clay by CS in the latter case.