Destabilization of Oil-in-Water Emulsions Stabilized by Non-ionic Surfactants: Effect of Particle Hydrophilicity

Abstract

We investigate the use of particle hydrophilicity as a tool for emulsion destabilization in Triton-X-100-stabilized hexadecane-in-water emulsions. The hydrophilicity of the particles added to the aqueous phase was found to have a pronounced effect on the stability of the emulsion. Specifically, the addition of hydrophilic fumed silica particles to the aqueous phase resulted in coarsening of the emulsion droplets, with droplet flocculation observed at higher particle concentrations. On the other hand, when partially hydrophobic fumed silica particles were added to the aqueous phase, coarsening of the emulsion droplets was observed at low particle concentrations and phase separation of oil and water was observed at higher particle concentrations. Surface tension and interfacial tension measurements showed significant depletion of the surfactant from the aqueous phase in the presence of the partially hydrophobic particles. The observed changes in the stability of the emulsion and the depletion of the surfactant can be rationalized in terms of changes in the adsorption behavior of the surfactant molecules, from one dominated by hydrogen bonding on hydrophilic particles to one dominated by hydrophobic interactions on partially hydrophobic particles. Our findings also provide, for the first time, an in-depth understanding of antagonistic (destabilizing) effects in mixtures of partially hydrophobic particles and a non-ionic surfactant (Triton X-100) in water.

Charge-controlled microfluidic formation of lipid-based single- and multicompartment systems

“…This might be due to micellar exclusion of the surfactants from the droplet interfaces as a result of interactions between Krytox and the PEG-based fluorosurfactants. 32,33 Samples that exhibited flocculation ultimately showed droplet coalescence after a few days (ESI, † Fig. S11).…”

Janus Particles at Fluid Interfaces: Stability and Interfacial Rheology

“…Hence, by tuning the interactions and switching from a repulsive to attractive potential, clustering and aggregate formation can be stimulated [120,[171][172][173]. A plethora of opportunities exists for tuning the colloidal interactions for instance through particle wettability, introducing anisotropy, addition of electrolytes, solution pH, and synergism in presence of surfactants [9,29,174,175]. For example, Horozov et al observed that silica particles of low hydrophobicity (θ E = 65…”

“…A large value of binding energy relative to the thermal energy can therefore lead to irreversibly adsorbed particles at the interface [11][12][13][14][15][16][17]. As such, parameters including particle size, wettability, and concentration have been used to alter the stability of emulsions and foams [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33]. With the recent advancements in synthesis and fabrication techniques, particle anisotropy (both in shape and surface properties) has been introduced as another avenue for manipulating the behavior of particles at fluid interfaces.…”

Evaluation of Nanoemulsion Concentrate Botanical Fungicide from Neem, Citronella and Eugenol Oil Using Palm Oil Based Surfactant

“…MES and PDO tend to oil soluble while PMO tend to water soluble. The composition of surfactant 70% consist of PMO indicate a dominant hydrophilic affinity which interact with particle surface in water through hydrogen bonding to form oil in water nanoemulsion [18]. The emulsion stability was observed manually for six hours and the destabilization phenomenon was recorded every ten minutes.…”