Emulsion Inversion Point Method Research Articles

Simple preparation of silicone rubber Pickering emulsions using silica nanoparticles for water-borne thermal protection coating

Abstract In this study, we aimed to develop stable silicone rubber Pickering emulsions by employing silica nanoparticles as stabilizers in order to produce a water-borne thermal protection coating. Initially, silica nanoparticles were synthesized using the Stöber method and subsequently functionalized with γ-glycidoxypropyltrimethoxysilane (GTMS). The size and grafting efficiency of the GTMS-modified silica nanoparticles were characterized using transmission electron microscopy and thermogravimetric analysis, respectively. Furthermore, the functionalization mechanism was elucidated by monitoring the pH and Zeta potential of the silica sols. Subsequently, the silicone rubber Pickering emulsion was prepared via the emulsion inversion point method and characterized using transmission electron microscopy. The emulsification process was analyzed by measuring the conductivity of the emulsion during the phase transition. Finally, the water-borne coating was formulated by blending the emulsions with Kaolin, glass fiber, and glass microspheres. The thermal protection performance of the resulting coating was evaluated under typical test conditions, with the highest heat flow reaching 242 kW m−2 for 40 s.

Nanoencapsulation of Vitamin D3 by the Emulsion Inversion Point Method for Enrichment of Coconut Yogurts

Nanoencapsulation of Vitamin D₃ by the Emulsion Inversion Point Method for Enrichment of Coconut Yogurts

Technological and sensory evaluation of pineapple ice creams incorporating curcumin‐loaded nanoemulsions obtained by the emulsion inversion point method

This study evaluated the feasibility of incorporating curcumin‐loaded nanoemulsions (CLNE) produced by the emulsion inversion point method in pineapple ice creams to replace artificial yellow dyes. For this purpose, ice creams with formulations: A (pineapple flavour commercial mix), B (partial replacement of commercial mix by CLNE), C (complete replacement of commercial mix by CLNE) and D (complete replacement of commercial mix by nonencapsulated curcumin) were characterized. Results showed that CLNE incorporation was a feasible alternative for reducing the use of artificial dyes, as the ice creams showed similar physicochemical and rheological properties, and formulations A and B had similar sensory acceptance.

Ultrasound assisted manufacturing of paraffin wax nanoemulsions: Process optimization

This work reports on the process optimization of ultrasound-assisted, paraffin wax in water nanoemulsions, stabilized by modified sodium dodecyl sulfate (SDS). This work focuses on the optimization of major emulsification process variables including sonication time, applied power and surfactant concentration. The effects of these variables were investigated on the basis of mean droplet diameter and stability of the prepared emulsion. It was found that the stable emulsion with droplet diameters about 160.9nm could be formed with the surfactant concentration of 10mg/ml and treated at 40% of applied power (power density: 0.61W/ml) for 15min. Scanning electron microscopy (SEM) was used to study the morphology of the emulsion droplets. The droplets were solid at room temperature, showing bright spots under polarized light and a spherical shape under SEM. The electrophoretic properties of emulsion droplets showed a negative zeta potential due to the adsorption of head sulfate groups of the SDS surfactant. For the sake of comparison, paraffin wax emulsion was prepared via emulsion inversion point method and was checked its intrinsic stability. Visually, it was found that the emulsion get separated/creamed within 30min. while the emulsion prepared via ultrasonically is stable for more than 3 months. From this study, it was found that the ultrasound-assisted emulsification process could be successfully used for the preparation of stable paraffin wax nanoemulsions.

Enhancement of aqueous stability of allyl isothiocyanate using nanoemulsions prepared by an emulsion inversion point method

Allyl isothiocyanate (AITC), an organosulfur compound in cruciferous vegetables, is a natural antimicrobial and potential chemopreventive agent. However, the instability of AITC in aqueous systems restrains its applications. In this study, oil-in-water AITC nanoemulsion was prepared by the emulsion inversion point (EIP) method, aiming at improving the aqueous stability of AITC. The optimal hydrophilic–lipophilic balance (HLBop) value of surfactants containing Tween 80 and Span 80 was established at 11.0–13.0, yielding nanodroplets with diameters of 137–215nm. The mechanism of droplet formation within the HLPop region was discussed in terms of the possible structure of adsorbed surfactant layers at the oil–water interface in multiple emulsion droplets. In a 6.5-month storage test, the droplet sizes and the count rates (intensity of scattered light) of nanoemulsions decreased only slightly by 4–13% (depending on surfactant-to-oil ratio), even in highly diluted status, indicating the desirable stability of the nanoemulsions. Moreover, the nanoemulsion demonstrated superior protection against AITC degradation (78% remaining after 60d at 30°C), compared with protein nanoparticles as well as non-encapsulated aqueous dispersion. This work shows for the first time that AITC can be formulated into nanoemulsions and thus obtains satisfactory aqueous solubility and chemical stability.

Formation and properties of paraffin wax submicron emulsions prepared by the emulsion inversion point method

Paraffin wax-in-water submicron emulsions stabilized by Span 80/Tween 80 were prepared by the emulsion inversion point (EIP) method. Stable emulsions with droplet diameters about 700 nm could be formed when the hydrophilic–lipophilic balance (HLB) values are between 9.5 and 10.3 and the surfactant-to-oil ratio is above 0.2. Increased emulsification temperature and cooling rate were found to improve the emulsion properties. Either mixing all components together or addition of oil to the aqueous surfactant dispersion could not produce stable emulsions. Optical microscopy and scanning electron microscopy (SEM) were used to study the morphology of the emulsion droplets. The droplets were solid at room temperature, showing bright spots under polarized light and an irregular spheres shape under SEM. Due to homogeneous nucleation in the finely dispersed emulsion droplets, the emulsion shows a large degree of undercooling (15 °C) in the differential scanning calorimetry (DSC) thermogram. The emulsions became unstable with heating, but remained stable under cooling. The electrophoretic properties of emulsion droplets showed a negative zeta potential, which was increased with the pH of the system due to the adsorption of hydroxyl groups.

Formulation and stability of whitening VCO-in-water nano-cream

Virgin coconut oil (VCO)-in-water, nano-emulsion in the form of cream stabilized by Emulium Kappa ® as an emulsifier, was prepared by using the Emulsion Inversion Point method. A nano-emulsion with droplet size <300 nm was then obtained. VCO has recently become a more popular new material in the cosmetic industries. Emulium Kappa ® is an ionic emulsifier that contains sodium stearoyl lactylate, the active whitening ingredient was Kojic Dipalmitate. Ostwald ripening is the main destabilizing factor for the nano-emulsion. This decline can be reduced by adding non-soluble oil, namely squalene, to the virgin coconut oil. We tested VCO:squalene in the ratios of 10:0, 9.8:0.2, 9.6:0.4, 9.4:0.6, 9.2:0.8, 9:1 and 8:2 and discovered that squalene's higher molecular weight (above critical molecular weight) resulted in low polarity and insolubility in the continuous phase. The continuous partitioning between the droplets results in the decline of Ostwald ripening. Furthermore, flocculation may occur due to the instability of nano-emulsion, especially for the preparations with little or no squalene at all. The stability of the nano-emulsion was evaluated by the electrophoretic properties of the emulsion droplets. The zeta potential values for the emulsion increased as the percentage of squalene oil increased.

Formation and stability of paraffin oil-in-water nano-emulsions prepared by the emulsion inversion point method

Paraffin oil-in-water nano-emulsions stabilized by Tween 80/Span 80 were prepared using the emulsion inversion point method at different emulsification temperatures. Nano-emulsions with droplet size below 200 nm were formed above a critical surfactant-to-oil ratio of 0.20 at 50 °C. The main destabilization mechanism of the systems was found to be Ostwald ripening. An interesting phenomenon was that the Ostwald ripening rate declined as the surfactant concentration rose. Furthermore, flocculation was also found to contribute to the instability of the nano-emulsions, especially for those with low surfactant concentrations. Study on the electrophoretic properties of emulsion droplets revealed a negative value of the zeta potential, which was strongly dependent on the pH of the systems.

Nano-emulsions preparation by low energy methods in an ionic surfactant system

The emulsion inversion point method was used to form nano-emulsions in the ionic system water/oleic acid–potassium oleate–C12E10/hexadecane. Potassium hydroxide solutions were added to oleic acid–C12E10/hexadecane solutions at constant temperature (25°C) in order to obtain nano-emulsions at 80% water concentration, with a stoichiometric relation of oleic acid and KOH at this point. So, the ionic surfactant (the potassium oleate) was formed along the emulsification path. The influence of the phases present during the emulsification process on nano-emulsion droplet size was analized. The results show that the smallest droplet size is obtained when along the emulsification path and near the nano-emulsion region the equilibrium is achieved with all the oil dissolved in a phase, in this case in a cubic liquid crystalline phase. It has also been found that the most probable breakdown mechanism of the nano-emulsions formed is Ostwald Ripening.