Spin Coating for Forming Thin Composite Coatings of Montmorillonite and Poly(vinyl alcohol) br

Montmorillonite (MMT) nanosheets were coas-sembled with poly(vinyl alcohol) (PVA) via a spin-coating process.The resulting coating layer, consisting of a multilayered nano-composite structure, possessed an outstanding barrier propertythanks to the highly ordered structure of the MMT nanosheetscreating a tortuous path for molecular diffusion. The process ofalignment and stacking of MMT nanosheets on a solid substrate iscontrolled by an array of factors, some of which can be controlledby the coating process. To this end, the suspension concentrationand spin speed were varied to determine their impact on thefinalfilm quality. The turbidity of thefilms was quantified usingultraviolet-visible (UV-VIS) spectroscopy. The structure of thenanocoating layers was verified via X-ray diffraction (XRD).Finally, the overall performance of the coatings was tested via oxygen transmission rate (OTR) measurements, which gives anindication of the nanosheet assembly structure. The presence of high centripetal acceleration resulted in high degrees of nanosheetalignment and a high barrier to oxygen transport. This coating technique has unique implications for thin-film vapor barriertechnologies such as solar cells, dielectric materials, and biomedical devices