Miniemulsion-derived pMMA-stabilized vitamin C nanoencapsulations: synthesis, characterization and formulation optimization study

Vitamin C (L-ascorbic acid) is a widely used antioxidant in cosmeceutical formulations; however, its application is limited by poor stability and susceptibility to degradation. In this study, stable vitamin C nanodroplets were fabricated via an inverse miniemulsion technique and subsequently encapsulated through interfacial polymerization of methyl methacrylate to form poly(methyl methacrylate) (pMMA) core–shell structures. The effects of glucose and poly(butylene-co-ethylene)-b-poly(ethylene oxide) (PB/E-b-PEO) on droplet size and stability were systematically investigated. Response surface methodology (RSM), based on a central composite design (CCD), was employed to optimize formulation parameters, yielding an optimal composition of 0.65 g glucose and 1.0 g PB/E-b-PEO, producing nanodroplets with an average size of 181 nm (PDI = 0.264). Following encapsulation, the pMMA-coated nanodroplets exhibited particle sizes in the range of 151–211 nm with moderate polydispersity (PDI = 0.259–0.362) and maintained excellent colloidal stability over 90 days, as confirmed by dynamic light scattering (DLS). Morphological and structural analyses (TEM, XRD, and FTIR) verified the formation of spherical nanodroplets with well-defined polymer shells, consistent with an interfacial polymerization mechanism. These findings demonstrate that inverse miniemulsion combined with controlled polymerization provides an effective platform for stabilizing labile bioactive compounds, with strong potential for advanced cosmeceutical delivery applications.