Tailoring starch-based films with monoglyceride and montmorillonite: Molecular interactions, hydrophobicity, and barrier properties

Abstract

Herein, a novel multilayer starch-based film was engineered through the strategic incorporation of monoglyceride (MG) and montmorillonite (MMT) to simultaneously enhance hydrophobicity and barrier properties. Molecular dynamics (MD) simulations elucidated the non-covalent interactions within the film matrix. Characterization by scanning electron microscopy (SEM), atomic force microscopy (AFM), and UV–visible spectroscopy revealed uniform film formation and well-controlled surface roughness. The resulting starch-MMT-MG composite exhibited excellent optical clarity, with visible light transmittance of 77.78 % at 700 nm and strong UV-shielding capacity (40.88 % at 300 nm). As hypothesized, positioning MMT in the middle layer and applying MG as a top coating yielded a film with uniform formation and controlled surface roughness. This configuration led to the film's superior water resistance, as evidenced by the lowest water solubility (WS) of 15.83 %, the highest contact angle (CA) of 109.36°, and a reduced water vapor permeability (WVP) of 0.78 × 10⁻¹⁰ g·m·m⁻²·s⁻¹·Pa⁻¹. Mechanical testing further demonstrated the film's robustness and flexibility, showing a Young's modulus of 128.24 MPa, tensile strength of 16.58 MPa, and elongation at break of 58.66 %. Consistent with these experimental findings, MD simulations verified stable hydrogen bonding between starch and MG, highlighting their strong molecular compatibility. Collectively, these results underscore the promise of starch-MMT-MG films as multifunctional, sustainable materials for advanced packaging applications.