Biocompatible Degradable Hollow Nanoparticles from Curable Copolymers of Polylactic Acid for UV-Shielding Cosmetics

Hollow polymeric nanoparticles have attracted vast attention as UV-shielding materials in personal care products due to their excellent light scattering characteristics and low density. In this work, a process for fabricating biocompatible/degradable poly(lactic acid-co-glycidyl methacrylate), P(LA-co-GMA), hollow nanoparticles via one-step phase inversion emulsification is examined, to gain insights into their formation mechanisms and optimization of the process parameters. The migration of poly(vinyl alcohol) (PVA) (stabilizing agent) from the oil droplet to the oil/water interface while entangled with cross-linked P(LA-co-GMA) chains and the fast evaporation rate of the chloroform solvent play an essential role in the hollow structure formation. Under optimum conditions, monodispersed hollow nanoparticles, with an average size of 500–700 nm and good colloidal stability, are obtained. The as-prepared hollow nanoparticles exhibit high UV shielding capabilities and low toxicity. The nanoparticles show high stability under UV exposure but can be completely degraded within 24 weeks under accelerated hydrolysis conditions. The materials have a high potential for use as environmental-friendly UV-shielding additives in cosmetic applications.