An environmentally friendly synergistic stabilization of emulsions using an ABC macrosurfactant and hydroxypropyl methylcellulose

Here, a series of non-ionic ABC based on the hydrophilic oligo- and di-(ethylene glycol) methyl ether methacrylate (OEGMA300/A and DEGMA/C), and the hydrophobic n-butyl methacrylate (BuMA, B) are investigated as macrosurfactants. Polymers of constant composition, and four varying molar masses (MM) were synthesized via group transfer polymerization. The higher the MM, the bigger the micelles in aqueous media, and the lower the critical micellization concentration and the stability of oil-in-water emulsions. The best-performing macrosurfactant was investigated under different conditions and it was proven that the oil phase volume fraction, and surfactant concentration strongly control the emulsion stability. The macrosurfactants show minimal dependence on the salinity of the water phase, thus offering suitability in preparation of emulsion in environments with different hardness. Emulsions stabilized by both the macrosurfactant and hydroxypropyl methylcellulose (HPMC), a naturally derived viscosity modifier, present a classical non-Newtonian behavior; the viscosity increased when increasing the MM of the HPMC. The emulsion stabilization is attributed to the synergistic steric stabilization provided by the macrosurfactant and the increased viscosity and formation of an entangled network by HPMC. This formulation leads to emulsion stability over 65% 1 year after emulsification, highlighting its potential use in commercial applications.