Pickering emulsions stabilized by self-assembled polymeric micelles of coumarin-containing cross-linkable amphiphilic terpolymer

Abstract

To elucidate the correlation between the oil-water interfacial property and emulsifying performance of polymeric micelles, the polymeric particulate emulsifiers based on the self-assembled micelles of amphiphilic poly(2-(dimethylamino)ethyl methacrylate-co-styrene-co-7-(4-vinylbenzyloxyl)-4-methylcoumarin) (PDSV) had been successfully prepared. The micelle size, morphology, self-assembly behavior, and photo-cross-linking were investigated with a combination of dynamic light scattering (DLS), transmission electron microscopy (TEM), and ultraviolet-visible spectrophotometer. Further systematic investigation on PDSV19 micelles was focused on both emulsifying performance and oil-water interfacial behavior. The larger degree of photo-cross-linking, the poorer emulsifying performance. The DMAEMA unit of PDSV underwent the inversion from protonation to deprotonation with the increasing pH, causing the observed o/w to w/o phase inversion, allowing for direct control over the emulsion stability. Styrene with 1.0 mol% initiator as oil phase and PDSV19 micelles as emulsifiers were employed to prepare solidified polymerized beads. PDSV19 nanoparticles could maintain a good spherical morphology, with most of them adsorbing at the interface or embedding into the solidified polymerized beads whether in acidic, neutral, or alkaline conditions. Moreover, great stacking of PDSV19 nanoparticles was observed at pH 10.3, indicating better emulsifying performance and stability. This paper may be helpful in understanding stimuli-responsive Pickering emulsions stabilized by random terpolymer micelle-based particulate emulsifiers.