2 mg CS-CaCl2coating sample was scraped from the glass. The tested samples (CS-CaCl2coating and pure CS pow-der) were pressed into a disc with 200 mg of KBr to gain the FT-IR spectra. FT-IR was recorded to analysis their chemical structure.The measurement of FT-IR spectra was carried out with a Nicolet Nexus-470 Fourier transform infrared spectrometer (Thermo Nico-let, USA) at the wavenumber region of 4000–400 cm−1using 32scans