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Shellac Thin Films Obtained by Matrix-Assisted Pulsed Laser Evaporation (MAPLE)

Year: 2018

Journal: Coatings, Volume 8, AUG

Authors: Brajnicov, Simona; Bercea, Adrian; Marascu, Valentina; Matei, Andreea; Mitu, Bogdana

Keywords: thin films; matrix-assisted pulsed laser evaporation; shellac; enteric coatings

We report on the fabrication of shellac thin films on silicon substrates by matrix-assisted pulsed laser evaporation (MAPLE) using methanol as matrix. Very adherent, dense, and smooth films were obtained by MAPLE with optimized deposition parameters, such as laser wavelength and laser fluence. Films with a root mean square (RMS) roughness of 11 nm measured on 40 x 40 mu m(2) were obtained for a 2000-nm-thick shellac film deposited with 0.6 J/cm(2) fluence at a laser wavelength of 266 nm. The MAPLE films were tested in simulated gastric fluid in order to assess their capabilities as an enteric coating. The chemical, morphological, and optical properties of shellac samples were investigated by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and atomic force microscopy (AFM).