Hydroxyethyl cellulose as carbohydrate polymer scaffold for surfactant-free serums with enhanced hydration and...

Conventional cosmetic serums often suffer from rapid dehydration, phase separation, and component aggregation, leading to non-uniform ingredient dispersion and limited hydration durability. In this study, hydroxyethyl cellulose (HEC) was investigated as a structural modifier to improve the physicochemical stability and moisturizing performance of surfactant-free cosmetic serums. Moisture retention tests showed that HEC-containing formulations exhibited improved hydration durability, with moisture loss limited to approximately 5% after 30 min even after 7 days of storage. Extended measurements further showed that HEC-containing systems maintained higher moisture retention over longer time scales than HEC-free formulations. Scanning electron microscopy revealed a smoother and more homogeneous dried microstructure in the presence of HEC, indicating improved structural uniformity without conventional surfactants. Thermogravimetric analysis showed altered dehydration behavior, suggesting modified water-binding environments rather than changes in intrinsic thermal stability. FT-IR spectroscopy with peak deconvolution provided strong evidence for intermolecular hydrogen bonding between the hydroxyl groups of HEC and the carbonyl groups of sodium hyaluronate, while complementary ¹H NMR analysis revealed peak broadening and subtle chemical shift variations, indicating changes in local proton environments and intermolecular interactions. These results support the formation of a stabilized polymeric network by HEC, which contributes to improved structural integrity and sustained hydration performance in surfactant-free serum systems.