Potential of sustainable, ecofriendly sterol derivatives as additives for water and oil repellency

An increasing global demand for sustainable packaging and protective materials has led to significant interest in developing effective water-resistant and oil-repellent materials from natural resources. This is because some of the current synthetic water-resistant and oil-repellent materials are made from organofluorine compounds. This study explored the potential of isoprenoid compounds, such as sterols, as biobased replacements for surface coating or packaging applications. The hydrophobicity and oleophobicity of various sterols and related structural compounds coated on silicon wafers and annealed at 60 °C and 140 °C were evaluated. As the annealing temperature increased, the hydrophobicity of sterol groups, such as cholesterol, ergosterol, β-sitosterol, and stigmasterol, increased, with their contact angles ranging from 100.7 ± 0.5° to 105.7 ± 1.1° when annealed at 140 °C. Moreover, cholesterol myristate and stearyl glycyrrhetinate exhibited good hydrophobicity and oleophobicity characteristics when annealed at 60 °C, with water contact angles of 106.4 ± 0.2° and 100.9 ± 0.7° and hexadecane contact angles of 46.1 ± 1.1° and 47.6 ± 5.0°, respectively. Based on the findings of this study, isoprenoids have potential as sustainable alternatives to water and oil repellents, particularly in applications where hydrophobicity is essential. Furthermore, this study offers valuable insights into the significant role of the annealing temperature in enhancing coating properties.