The Polymer Society of Korea

Abstract

Phenylbenzimidazole sulfonic acid(PBSA) is a representative water-soluble UV filter, but its UV protection in aqueous formulations is often limited. In this study, we propose that the limited UV protection of PBSA in aqueous systems arises from spreading and film-forming behavior rather than intrinsic molecular absorbance. Accordingly, we examine the influence of incorporating hydrophilic polymers on the surface coverage behavior and UV-blocking performance of aqueous PBSA systems. The results showed distinct polymer-dependent differences in UV-blocking performance, which were associated with the film uniformity. Notably, systems containing poly(vinyl alcohol)(PVA) and gelatin formed continuous surface coverage due to viscoelastic behavior together with interfacial adsorption, whereas polyethylene glycol(PEG) and dextran resulted in discontinuous coverage. These findings highlight the importance of mechanism-based design for oil-free and eco-friendly water-based UV protection systems.