Phase Inversion Emulsification Research Articles

Development and characterization of multiple emulsions for controlled release of Trichilia catigua (Catuaba) extract

Considering the antioxidant activity of the Trichilia catigua extract (TCE), the aim of the current study was to develop and characterize W/O/W multiple emulsions containing different vegetable oils as a platform to deliver a TCE. The extract displayed antioxidant activity (IC50) of 4.59 µg/mL and total phenol content (TPC) of 50.84%. Formulations were prepared by the phase-inversion emulsification method and analyzed for morphological appearance, pH, conductivity, droplet size and distribution, content of active, rheological properties, in vitro release, skin permeation, and stability. Formulations prepared with canola oil were selected and displayed regular morphology, mean diameter 2.77 µm (without TCE), 3.07 µm with 0.5% and 3.23 µm with 1.0% TCE. Rheometry (flow) showed pseudoplastic behavior with minimal thixotropy for both systems. TCE could be released from emulsions containing 1.0% and 0.5% TCE in a controlled manner for 16 and 23 h, respectively. The emulsions allowed good retention of TCE in the skin (stratum corneum, epidermis, and dermis). In a 180-d assessment of accelerated chemical stability, TPC was more reduced for the emulsions at 40 °C; other parameters remained stable. Multiple emulsions containing TCE were developed, exhibited good characteristics, and may be considered for future investigations as anti-aging formulations for the skin.

Recent Developments in Phase Inversion Emulsification

Emulsions are multiphasic fluid systems in which liquid droplets are dispersed in another immiscible liquid. The main components of an emulsion are the two liquid phases, typically oil and water, a...

Synthesis and properties of triethoxysilane-terminated anionic polyurethane and its waterborne dispersions

The paper presents a new method to prepare waterborne anionic alkoxysilane-terminated polyurethane dispersion (SPUD) which is substantially free from organic solvent: the NCO-terminated polyurethane (PU) containing carboxylic ions in backbone is synthesized by melt polycondensation with toluene 2,4-diisocyanate (TDI), polypropylene oxide (PPO) and 2, 2-dimethylolbutanoic acid (DMBA), the terminal NCO groups are reacted with 3-aminopropyltriethoxylsilane (APTES) to give alkoxysilane-terminated PU (SPU), and the waterborne SPUD with higher aminosilane content (10 wt% in SPU) is obtained by phase-inversion emulsification with the aid of protective colloid (polyethermethylsiloxanes, PEMS) and external emulsifier (sodium dodecyl sulfate, SDS). The anionic PU and SPU are characterized by FT-IR, gel permeation chromatography (GPC), differential scanning calorimeter (DSC) and thermo-gravimetric analysis (TGA). The thermal studies show that SPU has lower Tg than anionic PU as well as thermal stability. The effects of emulsifier, protective colloid, solid content and pH value on the storage stability of waterborne SPUD are investigated, respectively. The results indicate that the storage stability decreases with increasing viscosity and dispersing ratio, whereas particle size and polydispersity index (PDI) are hardly affected by the solid content, the amount of emulsifier and protective colloid. The SPUD prepared with about 2 wt% SDS, 5 wt% PEMS, 31 wt% solid content and pH value of 7 is stable for more than 6 months at 50 °C and 8 months at room temperature, while exhibiting excellent freeze-thaw stability. The corresponding cured films exhibit excellent mechanical properties with 19.2 MPa tensile strength and 320 % elongation at break.

The effect of soft segment on the microstructure and mechanical properties of waterborne UV-curable polyurethane/silica nanocomposites

Waterborne UV-curable polyurethane (WUPU)/silica nanocomposites were prepared using various types of polyol (PCL, PBA, and PCD) by phase-inversion emulsification. The PCL-WUPU nanocomposite dispersion exhibited larger particles and higher viscosity than the PBA-WUPU and PCD-WUPU nanocomposite dispersions. The TEM analysis indicated that many small silica clusters and a few big silica clusters were distributed in the PCL-WUPU matrix, whereas the silica nanoparticles and the continuous silica network were homogeneously dispersed in the PBA-WUPU and PCD-WUPU matrix, respectively. The DMA analysis demonstrated that the broadening of the tanδ peaks or breadth of segmental motion at lower or higher temperatures were observed for WUPU nanocomposite films, suggesting the different interaction between WUPU and silica. The WUPU nanocomposite films showed increased the storage modulus, Young’ modulus, and tensile strength. But for toughness, the PCL-WUPU nanocomposite film exhibited higher improvement than PBA-WUPU and PCD-WUPU due to the silica nanoparticles preferentially, but not exclusively interaction with the hard segment of WUPU. This study provides clues for exploiting silica-polyurethane interactions to control the silica nanoparticles dispersion and tune material properties without surface modification of silica nanoparticles.

Emulsion phase inversion from oil-in-water (1) to water-in-oil to oil-in-water (2) induced by in situ surface activation of CaCO3 nanoparticles via adsorption of sodium stearate

Abstract In the oil exploitation process, the conversion from water-in-oil emulsion to oil-in-water emulsion is usually needed for a better cementing quality after using the water-in-oil emulsion drilling fluid. Due to the advantages of both oil-external properties for drilling and water-external characteristics for completion, the reversible emulsion drilling fluids are being used in drilling industry. The researches about phase inversion of emulsion induced by nanoparticles and amphiphilic compounds are also being conducted. Using white oil–water system, emulsion stabilized by CaCO3 nanoparticles and sodium stearate was investigated. The raw CaCO3 nanoparticles were activated in situ by interaction with sodium stearate in aqueous solution. The mechanism of the in situ surface activation was accessed by means of emulsion characterization, adsorption measurement and contact angle. The results show that raw CaCO3 nanoparticles can be activated in situ as emulsifiers by interaction with sodium stearate. With the monolayer and bilayer formed at the CaCO3 nanoparticles–water surface by absorption of different concentrations of sodium stearate, the wettability of the particles will transform from hydrophilicity to hydrophobicity and then back to hydrophilicity. The change of wettability may induce a phase inversion of emulsions from oil-in-water O/W (1) to water-in-oil W/O and re-invert to oil-in-water O/W (2). CaCO3 nanoparticles can thus be used as good stabilizers of both O/W and W/O emulsions once activated in situ by mixing with suitable amounts of sodium stearate.

Vitamin E nanoemulsions by emulsion phase inversion: Effect of environmental stress and long-term storage on stability and degradation in different carrier oil types

Abstract Physicochemical stability and thermal degradation of vitamin E (VE) in nanoemulsions fabricated by low energy emulsification method known as Emulsion Phase Inversion: catastrophic phase inversion (EPI) with different carrier oils (short-chain, medium-chain and long-chain triglycerides) and Tween 80 were investigated. Although nanoemulsions made with VE and the 3 carrier oils showed physical stability to heat shock (30–90 °C, 30 min), ionic strength (0–500 mM), pH (2.0–8.5) and long term storage (60 days, under light and darkness, 4, 25 and 40 °C), there was significant VE degradation in heat processed and long-term storage samples. The VE degradation in long-term storage fitted well with Weibull model, while heat degradation followed the first order kinetics, with medium-chain triglyceride (MCT) based nanoemulsions held at 90 °C showing the greatest degradation rate ( k = 0.1526 × 10 −3 min −1 ) and lowest half-life of 4.54 min. The lack of droplets aggregation or coalescence was associated with absence of electrostatic screening and ion-binding effects. The nanoemulsions stored at 4 °C were more stable than those at 40 °C. The short-chain triglyceride (SCT) based nanoemulsions did not physically withstand the high temperatures (>25 °C) while long-chain triglyceride (LCT) showed good retention in all studied conditions. The VE retention was increased when nanoemulsions were stored in the dark. This study might be helpful to food and pharmaceutical industries in choosing better processing and storage conditions of VE delivery systems.

Effect of composition on the TPI-Inverse emulsion polymerization of AM/AA-Na/AMPS-Na

In this paper, the inverse emulsion polymerization of AM/AA-Na/AMPS-Na was carried out after the transitional phase inversion (TPI) emulsification. The effects of monomer concentration ([M]) and surfactant concentration ([S]) on the formulation-composition map and polymerization were studied. For formulation-composition map, increasing [M] and decreasing [S] could induce an upward vertical displacement of the horizontal branch of the standard inversion frontier in the HLB scale. Simultaneously, B-/A- frontier and C-/A- frontier shifted to middle. The stability of copolymer emulsion and intrinsic viscosity of copolymer were affected by [M] and water fraction. In addition, the results of polymerization kinetics experiments showed that Rp ∞ [M]1.31 [S]-0.065 [I]0.68 and the apparent activation energy was 83.42 kJ·mol-1.

Effect of polyether soft segments on structure and properties of waterborne UV-curable polyurethane nanocomposites

Waterborne UV-curable polyurethane (WUPU)/silica nanocomposites were prepared using three types of polyether (PEO-PPO-PEO, PPG, and PTMG) and aqueous colloidal silica by phase-inversion emulsification. The PEO-PPO-PEO and PPG-WUPU nanocomposite dispersions exhibited smaller particles and higher viscosity than their pure WUPU dispersions, whereas PTMG-WUPU nanocomposite dispersion exhibited larger particles and higher viscosity than its pure WUPU dispersion. The SEM analysis indicated that the continuous silica clusters network was distributed in the PEO-PPO-PEO-WUPU matrix, whereas the separate silica clusters were dispersed in the PPG and PTMG-WUPU matrix, respectively. The DMA analysis demonstrated that a slight narrowing of the peak in tanδ and a shift in T g toward lower temperature were observed for the WUPU nanocomposite films with PEO-PPO-PEO and PPG. Conversely, the PTMG-WUPU nanocomposite film showed the insensitivity of the soft segment glass transition (T g) peak positions, supporting preferential attraction of the silica nanoparticles to the highly polar hard segments. The WUPU nanocomposite films showed increased storage modulus, Young’ modulus, and tensile strength. However, for toughness, only the PTMG-WUPU nanocomposite film exhibited great improvement when compared to its pure film due to the silica nanoparticles preferential, but not exclusive, interaction with the hard segment of WUPU.

Preparation of emulsion‐type thermotolerant sizing agent for carbon fiber and the interfacial properties of carbon fiber/epoxy resin composite

ABSTRACTA modified resin was synthesized through the reaction between dodecylamine and tetraglycidyldiaminodiphenylmethane (TGDDM), which was used as the film former of sizing agent for carbon fiber (CF). The sizing agents were prepared through phase inversion emulsification method. Fourier transform infrared spectroscopy (FTIR) was utilized to analyze the modified resin. Particle sizes of the sizing agents were tested to evaluate their stabilities. Differential scanning calorimetry (DSC) results demonstrated that the glass transition temperature (Tg) of the modified TGDDM is much higher than the Tg of the cured epoxy resin E‐44. The influences of the sizing treatment on CF were investigated by abrasion resistance, fluffs, and stiffness tests. The maximum abrasion resistance increased by 172.8%, compared with the abrasion resistance of the desized CF. Interlaminar shear strength (ILSS) results of the CF/TGDDM composites indicated that the interfacial adhesion between CF and matrix resin was greatly improved after CF was sized. The maximum ILSS value could obtain a 29.16% improvement, compared with the ILSS of the desized CF composite. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41882.

Phase inversion of ionomer-stabilized emulsions to form high internal phase emulsions (HIPEs).

Herein, we report the phase inversion of ionomer-stabilized emulsions to form high internal phase emulsions (HIPEs) induced by salt concentration and pH changes. The ionomers are sulfonated polystyrenes (SPSs) with different sulfonation degrees. The emulsion types were determined by conductivity measurements, confocal microscopy and optical microscopy, and the formation of HIPE organogels was verified by the tube-inversion method and rheological measurements. SPSs with high sulfonation degrees (water-soluble) and low sulfonation degrees (water-insoluble) can stabilize oil-in-water emulsions; these emulsions were transformed into water-in-oil HIPEs by varying salt concentrations and/or changing the pH. SPS, with a sulfonation degree of 11.6%, is the most efficient, and as low as 0.2 (w/v)% of the organic phase is enough to stabilize the HIPEs. Phase inversion of the oil-in-water emulsions occurred to form water-in-oil HIPEs by increasing the salt concentration in the aqueous phase. Two phase inversion points from oil-in-water emulsions to water-in-oil HIPEs were observed at pH 1 and 13. Moreover, synergetic effects between the salt concentration and pH changes occurred upon the inversion of the emulsion type. The organic phase can be a variety of organic solvents, including toluene, xylene, chloroform, dichloroethane, dichloromethane and anisole, as well as monomers such as styrene, butyl acrylate, methyl methacrylate and ethylene glycol dimethacrylate. Poly(HIPEs) were successfully prepared by the polymerization of monomers as the continuous phase in the ionomer-stabilized HIPEs.

O/W型転相乳化着色エマルション特性に及ぼすポリマー物性の影響

O/W型転相乳化着色エマルション特性に及ぼすポリマー物性の影響

Complete incorporation of wax in polyester CPT using polyester-encapsulated wax emulsion

Polyester-encapsulated wax emulsions were investigated in the synthesis of polyester CPT to achieve a toner with complete incorporation of wax. The toner provided not only low-temperature fusing, but also improved durability, storage stability, and reduced contamination of print engine components. Polyester-encapsulated paraffin wax emulsions were prepared by phase-inversion emulsification with MEK as the solvent. To achieve good compatibility between the polyester resin and wax, the resin hydrophobicity was increased by grafting of hydrophobic moieties, including alkenyl succinic anhydride and styrene acrylate segments. With these resins, however, there was wax bleeding and separation of wax from the polyester emulsion. After evaluation of several resins, we found the following key conditions to achieve polyester emulsions with encapsulated wax. Firstly, the polyester was grafted with styrene acrylate segments containing long alkyl chain monomer such as stearyl methacrylate. Secondly, the wax was added internally to the hybrid polyester resin during resin synthesis. By using a resin produced under these conditions, the wax and polyester were emulsified with complete encapsulation of the wax, as confirmed by TEM. An EA toner was prepared from this emulsion and no wax was observed on toner surfaces by SEM. This means the wax stayed completely encapsulated even during coalescence, which was at a temperature above the wax melting point. In performance testing of the toner, the durability, storage stability and machine contamination levels were improved dramatically.

Low-energy formation of edible nanoemulsions by spontaneous emulsification: Factors influencing particle size

Nanoemulsions are used as delivery systems in food, pharmaceutical, and personal care applications for a variety of lipophilic active components, e.g., antimicrobials, flavors, colors, preservatives, vitamins, nutraceuticals, and drugs. In this study, we examined the effect of system composition and preparation conditions on the production of edible nanoemulsions using spontaneous emulsification (SE). SE is a low-energy method that simply involves addition of an organic phase (oil+surfactant) into an aqueous phase. The influence of surfactant-to-oil ratio (SOR), surfactant type, surfactant location, and oil type were tested. The droplet size produced decreased with increasing SOR, and was smallest when the non-ionic surfactant Tween 80 was used. Smaller droplets were formed when the surfactant was initially dispersed in the oil phase rather than the aqueous phase. Ten food-grade oils were tested and we found that droplet size followed the order: medium chain triglycerides<flavor oils<long chain triglycerides. No correlation was found between droplet size and the physicochemical characteristics of the oil phase (refractive index, density, interfacial tension, and viscosity). Results obtained by spontaneous emulsification were correlated to those obtained by emulsion phase inversion on similar systems suggesting a common underlying physicochemical mechanism.

Preparation and Properties of the Phase Inversion Emulsification of Epoxy Resin

The phase inversion process is a kind of efficient technology of emulsifying, it make its emulsifying ability to maximize by the means of control the factors of the HLB, the concentration of emulsifier, the ratio of emulsifier and oil and the temperature of emulsify. In this paper, the epoxy resin E-44 and polyethylene glycol used as materials, potassium persulfate as the catalytic agent, then we obtained the waterborne epoxy resin emulsion. The synthetic conditions of emulsifier, the mechanical stability and water-solubility of the emulsion were researched. Then the optimal amount of the emulsifier was determined and the modified emulsion was characterized, the particle size and viscosity were tested at the same time.

Shape-changing and amphiphilicity-reversing Janus particles with pH-responsive surfactant properties.

Janus particles are biphasic colloids that have two sides with distinct chemistry and wettability. Because of their amphiphilicity, Janus particles present a unique opportunity for stabilizing multiphasic fluid mixtures such as emulsions. Our work is motivated by one class of molecular amphiphiles that change their surfactant properties in response to environmental stimuli. Depending on the environmental conditions, these stimuli-responsive molecular amphiphiles are able to assemble into different structures, generate emulsions with different morphologies, and also induce phase inversion emulsification. We present a new synthesis method utilizing a combination of polymerization-induced phase separation and seeded emulsion polymerization, which allows for the bulk synthesis of highly uniform pH-responsive Janus particles that are able to completely reverse their surfactant properties in response to solution pH. One side of these Janus particles is rich in a hydrophobic monomer, styrene, whereas the other side is rich in a pH-sensitive hydrophilic repeating unit, acrylic acid. These Janus particles change their aggregation/dispersion behavior and also transform into different shapes in response to pH changes. Furthermore, we demonstrate that these Janus particles can stabilize different types of emulsions (oil-in-water and water-in-oil) and, more importantly, induce phase inversion of emulsions in response to changes in solution pH. The pH-responsive aggregation/dispersion behavior of these Janus particles also allows us to tune the interactions between oil-in-water emulsion droplets without inducing destabilization; that is, emulsion drops with attractive or repulsive interactions can be generated by changing the pH of the aqueous phase. Our study presents a new class of colloidal materials that will further widen the functionality and properties of Janus particles as dynamically tunable solid surfactants.

Enhancement of the antimicrobial properties of bacteriophage‐K via stabilization using oil‐in‐water nano‐emulsions

Bacteriophage therapy is a promising new treatment that may help overcome the threat posed by antibiotic-resistant pathogenic bacteria, which are increasingly identified in hospitalized patients. The development of biocompatible and sustainable vehicles for incorporation of viable bacterial viruses into a wound dressing is a promising alternative. This article evaluates the antimicrobial efficacy of Bacteriophage K against Staphylococcus aureus over time, when stabilized and delivered via an oil-in-water nano-emulsion. Nano-emulsions were formulated via thermal phase inversion emulsification, and then bacterial growth was challenged with either native emulsion, or emulsion combined with Bacteriophage K. Bacteriophage infectivity, and the influence of storage time of the preparation, were assessed by turbidity measurements of bacterial samples. Newly prepared Bacteriophage K/nano-emulsion formulations have greater antimicrobial activity than freely suspended bacteriophage. The phage-loaded emulsions caused rapid and complete bacterial death of three different strains of S. aureus. The same effect was observed for preparations that were either stored at room temperature (18-20°C), or chilled at 4°C, for up to 10 days of storage. A response surface design of experiments was used to gain insight on the relative effects of the emulsion formulation on bacterial growth and phage lytic activity. More diluted emulsions had a less significant effect on bacterial growth, and diluted bacteriophage-emulsion preparations yielded greater antibacterial activity. The enhancement of bacteriophage activity when delivered via nano-emulsions is yet to be reported. This prompts further investigation into the use of these formulations for the development of novel anti-microbial wound management strategies.

Optimization of isothermal low-energy nanoemulsion formation: Hydrocarbon oil, non-ionic surfactant, and water systems

Nanoemulsions can be fabricated using either high-energy or low-energy methods, with the latter being advantageous because of ease of implementation, lower equipment and operation costs, and higher energy efficiency. In this study, isothermal low-energy methods were used to spontaneously produce nanoemulsions using a model system consisting of oil (hexadecane), non-ionic surfactant (Brij 30) and water. Rate and order of addition of surfactant, oil and water into the final mixture were investigated to identify optimal conditions for producing small droplets. The emulsion phase inversion (EPI) and spontaneous emulsion (SE) methods were found to be the most successful, which both require the surfactant to be mixed with the oil phase prior to production. Order of addition and surfactant-to-oil ratio (SOR) influenced the particle size distribution, while addition rate and stirring speed had a minimal effect. Emulsion stability was strongly influenced by storage temperature, with droplet size increasing rapidly at higher temperatures, which was attributed to coalescence near the phase inversion temperature. Nanoemulsions with a mean particle diameter of approximately 60nm could be produced using both EPI and SE methods at a final composition of 5% hexadecane and 1.9% Brij 30, and were relatively stable to droplet growth at temperatures <25°C.

Nanoemulsion of AM/AA-Na/AMPS-Na Aqueous Solution and Kerosene Prepared by Phase Inversion Emulsification and Polymerization

Generally, the emulsion of AM/AA-Na/AMPS-Na aqueous solution and kerosene was prepared by direct emulsification in which the surfactant mixture was initially placed in the oil phase and then the water phase was added. Transitional phase inversion (TPI) emulsification has been widely used for preparation of ultrafine emulsions, but there is no report about the P(AM/AA-Na/AMPS-Na) nanoemulsion obtained by polymerization of TPI emulsion. In this article, first, the emulsions of AM/AA-Na/AMPS-Na aqueous solution and kerosene were prepared by four different methods, then, the properties of different emulsions and the corresponding results of polymerization were compared. The P(AM/AA-Na/AMPS-Na) nanoemulsion was obtained by the polymerization of TPI emulsion. Compared to the P(AM/AA-Na/AMPS-Na) emulsion obtained by direct emulsification, the P(AM/AA-Na/AMPS-Na) nanoemulsion obtained by the polymerization of TPI emulsion has higher molecular weight and better freeze–thaw stability and thermal stability.

Phase inversion in emulsions studied by low field NMR

Phase inversion phenomenon is studied using two novel low field NMR-based methods. The first method monitors the variation of the apparent spin-spin relaxation time (T2*) of the emulsions. It is based on the difference of the spin-spin relaxation time of water molecules inside a water droplet and within an aqueous bulk phase. The second method uses a diffusion measurement to distinguish between the water signal from droplets and the bulk. The relative distribution of water in droplets and in bulk can be measured. Moreover, droplet size distribution of water can be determined based on this method. Both methods were tested on the phase inversion of a model emulsion. A semi-batch process was used to perform the emulsification in situ. The information obtained through these methods is correlated to optical microscopy and conductivity measurements. When the phase inversion from w/o to o/w is induced by adding a hydrophilic surfactant to the nonionic Span® 80 the inversion seems to pass a double emulsion state before reaching the o/w state. This is an important observation to a mechanical understanding of the phase inversion.

Natural Brazilian Raw Material to Develop O/W Emulsions Containing Lamellar Gel Phase (Development and Analysis of Emulsion with Vegetable Oils)

Oil-in-water emulsions were developed employing the HLB system and emulsion phase inversion (EPI) method. X-ray diffraction revealed that the anisotropic structures around the inner phase globules were lamellar gel network phases. The calculated distances between the lamellae made after preparation and 3 month latter showed that there was no swelling of the lamellar gel network indicating good stability and few changes during storage. The developed emulsions were stable and have potential to be employed for cosmetic and pharmaceutical purposes. The gel phase network and vegetal components seemed to be contributing factors.