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Rice starch–activated carbon composite films for potential cosmetic facial sheet mask applications: physicochemical and mechanical characterization

Year: 2026

Type: article

Abstract: The widespread use of synthetic facial sheet masks has raised concerns about their environmental impact. In this study, rice starch (RS)–activated carbon (AC) composite films were prepared by solution casting and characterized to assess their potential as biodegradable cosmetic mask substrates. The surface morphology of the films changed after AC incorporation, with thicknesses ranging from approximately 0.2 to 0.3 mm and the moisture content increasing with increasing AC loading. The water contact angles ranged from 48.95° to 63.85°, indicating hydrophilic surfaces, with the RS + AC (0.4 g) film exhibiting the lowest measured contact angle. Fourier transform infrared spectroscopy suggested predominantly physical interactions between the RS and AC, whereas differential scanning calorimetry and X-ray diffraction characterized their thermal transitions and structural features. Compared with the neat RS film, the RS + AC (0.4 g) film exhibited lower tensile strength and elongation at break. MTT assays performed on AC powder revealed that the cell viability of L929 fibroblasts and HaCaT keratinocytes was above 90% under the tested conditions; the complete composite films were not evaluated for cytotoxicity. Soil burial testing revealed approximately 68.7% mass loss for the RS + AC film after 30 days. These findings support further investigations of RS + AC films as biodegradable cosmetic mask substrates. Their biocompatibility, water uptake, serum retention, and performance during skin application remain to be established.

Source: Scientific Reports

DOI: 10.1038/s41598-026-77095-3