Zein-Laponite nanocomposites with improved mechanical, thermal and barrier properties

Zein, a prolamin of corn, is a bio-renewable resource that can potentially offer alternatives for petroleum-based polymers in many applications. Nanocomposite formation with the addition of silicate nanoparticles (Laponite) to zein films, cast from 70% ethanol solutions, significantly improved the mechanical, thermal and barrier properties. Based on FTIR findings, a mechanism for zein-Laponite nanocomposite formation is proposed, which suggests Laponite nanoparticles bind to zein molecules through Si-N bond formation. Structural characteristics investigated using AFM and TEM confirmed exfoliation of the nanoparticle. The changes in the surface energy of the films were evaluated using water contact angle measurements and showed an increase in surface hydrophobicity. The Young's modulus and tensile strength increased with nanoparticle concentration. The glass transition temperature increased, and water vapor permeability decreased with only a small amount of Laponite.