Effects of different concentrations of ethanol and isopropanol on physicochemical properties of zein-based films

• Biodegradable zein-based films were prepared.
• The hydrophobicity of zein films was investigated.
• DSC was used to study the thermal stability of zein films.
• FTIR amide I deconvolution of zein films prepared from ethanol and isopropanol was shown.

In this study, biodegradable and biocompatible zein films were prepared by casting from alcoholic solutions. The effects of different types and concentrations of alcoholic solutions (ethanol and isopropanol) on hydrophobicity, mechanical and surface properties of zein during the plasticization process were investigated. It was demonstrated that at the initial phase, tensile strength of films increased with the increase of the concentration of ethanol and isopropanol solutions, reaching upon the maximum value (74.2 MPa and 57.5 MPa, respectively). In addition, the results of water contact angle, water vapor permeability, water absorption and transmittance indicated that the hydrophobicity of zein film prepared by ethanol was substantially higher than that prepared by isopropanol. Moreover, DSC (differential scanning calorimetry) and FTIR (Fourier transform infrared spectroscopy) revealed that the thermability and the secondary structure of zein film were affected by the presence of ethanol and isopropanol, respectively. In conclusion, the findings of this study may contribute to pragmatically formulate ideal surface morphology and the degree of hydrophobicity of zein based films fulfilling the different requirements from academia and industry.

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