A Study of the Relation between Bicontinuous Microemulsions and Oil/Water Nano-emulsion Formation

Abstract

Oil/water (O/W) nano-emulsions have been formed in the system water/C16E6/mineral oil by the phase inversion temperature (PIT) method. The relation between the phase equilibria observed at the hydrophilic−lipophilic balance (HLB) temperature or the PIT (i.e., the nature, number, and relative volume fractions of the involved phases), the droplet sizes, and polydispersities of the resulting emulsions have been determined. Milky white emulsions were obtained when, at the HLB temperature, a three-phase equilibrium formed by water (W), shear-birefringent microemulsion (D), and oil (O) was observed. However, bluish transparent O/W nano-emulsions with droplet sizes as low as 40 nm were formed in a narrow range of oil-to-surfactant ratios in which a D or W + D phases were the initial equilibrium phases. In the W + D equilibria, droplet sizes were independent from the water content, indicating that nanodroplet formation is mainly controlled by the structure of the D phase. These results suggest that the main requirement for bluish transparent O/W nano-emulsion formation is the complete solubilization of the oil component in a bicontinuous microemulsion, independent of whether the initial phase equilibrium is single or multiphase.

Nano-emulsion formation by emulsion phase inversion

“…Emulsions with droplet sizes between those of conventional emulsions and microemulsions, i.e. with a typical size range of 20-500 nm are termed mini-emulsions [1], ultrafine emulsions [2], submicron emulsions [3], translucent emulsions [4] and nano-emulsions [5,6]. Due to their small droplet size, nano-emulsions may appear transparent, and Brownian motion prevents sedimentation or creaming, hence offering increased stability.…”

“…Due to their small droplet size, nano-emulsions may appear transparent, and Brownian motion prevents sedimentation or creaming, hence offering increased stability. In contrast to microemulsions, nanoemulsions are metastable and can be diluted with water without changing the droplet size distribution [6].…”

“…1). This method is referred to as phase inversion temperature (PIT) method [6][7][8][9]. Instead of the temperature, other parameters such as salt concentration or pH value may be considered as well, generalized by considering the surfactant affinity difference (SAD) instead of the temperature alone [10].…”

Cement sheath modification using nanomaterials for long-term zonal isolation of oil wells: Review

“…Application of nanoparticles such as oxide nanoparticles, polymeric nanoparticles and nanoemulsions have demonstrated improved and cost-effective EOR processes (Del Gaudio et al, 2007;Morales et al, 2003;Zargartalebi et al, 2015). Nanotechnology has also led to the introduction of a new generation of smart fluids for drilling and completion applications.…”

Miniemulsion polymerization based on in situ surfactant formation without high-energy homogenization: effects of organic acid and counter ion

“…There are numerous reports describing miniemulsification techniques relying on catastrophic phase transitions occurring as a result of a change in temperature (phase inversion temperature method), 15,16 pressure, 17,18 pH, 19 ionic strength 20 or composition (emulsion inversion point method). 21,22 However, the application of such miniemulsification techniques to miniemulsion polymerization (as opposed to merely the miniemulsification process itself) has not been extensively investigated.…”