Antioxidant Pickering emulsions stabilized by core cross-linked diblock copolymer nanoparticles bearing polyphenol groups

Abstract

Pickering emulsions with antioxidative properties have significant applications across various fields such as biomedicine, skincare, and food. The fabrication of antioxidant Pickering emulsions using core cross-linked diblock copolymer nanoparticles bearing polyphenol groups as both Pickering emulsifiers and the interfacial reservoirs of antioxidants was demonstrated in this study. Poly[oligo(ethylene glycol) methyl ether methacrylate]₁₈-poly(diacetone acrylamide)₅₀ (POEGMA₁₈-PDAAM₅₀, E₁₈D₅₀) diblock copolymer nanoparticles were first synthesized via RAFT-mediated dispersion polymerization in water. Subsequently, PDAAM cores of E₁₈D₅₀ were chemically cross-linked using 4,6-diaminoresorcinol dihydrochloride (DAR.2HCl) as the cross-linker. The cross-linking process involved the Schiff base reaction between carbonyl groups of the PDAAM core-forming blocks and the amine groups of DAR.2HCl. Polyphenols were readily introduced into the cores of nanoparticles while the cross-linking of PDAAM core, affording core cross-linked copolymer nanoparticles bearing polyphenols (CCE₁₈D₅₀-P). The prepared CCE₁₈D₅₀-P nanoparticles exhibited excellent emulsification performances and outstanding free radical scavenging ability. Antioxidant dodecane-in-water Pickering emulsions were formulated using CCE₁₈D₅₀-P as Pickering emulsifiers, which demonstrated a desired effect in preserving vitamin E, with retentions of 88.4% and 82.1% after 28 days and 45 days of storage at room temperature, respectively.

Graphical Abstract