pH and reduction sensitive mesoporous silica nanoparticles for targeted drug delivery

To explore the self-assembling behavior and oil-water interfacial property of the micelle emulsifiers, a kind of coumarin-containing amphiphilic terpolymer, poly (2-(dimethylamino)ethyl methacrylate-co-methyl methacrylate-co-7-(4-vinyl benzyloxyl)-4-methylcoumarin) (PDMV), was prepared. The self-assembly polymeric micelles were used as particulate emulsifiers to stabilize stimuli-responsive emulsions. The micelle size, morphology, self-assembling behavior and photo-cross-linking were investigated with a combination of techniques. The critical water content (CWC) of terpolymers decreased with the increasing hydrophobic segments and initial concentrations. The larger degree of photo-cross-linking the micelles, the lower emulsifying efficiency the micelles. The tertiary amine groups of terpolymers underwent the inversion from protonation to deprotonation with the increasing pH, causing the observed o/w to w/o phase inversion, and there was coverage of spherical nanoparticle on the surface of polymerized styrene beads. Notably, macrophase separation and demulsification were observed under strong alkaline conditions, and some “reef-like” protuberances arose from a smooth surface of solidified polymerized beads. Thus the findings are not only of theoretical interest but also of great practical application in the polymeric surfactants and cosmetics area.