Regular Emulsion Research Articles

Monomer Transport by Collisions in (Mini) Emulsion Polymerization, a Personal Perspective

AbstractTransport of monomer from droplets to growing latex particles in emulsion polymerization in general is assumed to proceed via diffusion through the aqueous phase. Especially in miniemulsion polymerizations the direct transfer of very hydrophobic species from droplet to droplet is assumed to also proceed via collisions. Amongst the hydrophobic species where this is shown to play a role are monomers, initiators, inhibitors and (catalytic) chain transfer agents. It is well known that the reactor geometry and the stirring speed can have a profound effect on emulsion polymerizations. The 1972 paper of Nomura on the effect of stirring on emulsion polymerization is cited more than 100 times and until today keeps scientists intrigued. Diffusion limitations of monomer going from the droplet into the aqueous phase can occur for very hydrophobic monomers. The alternative route of transport via collisions is often not considered. In this perspective, paper will discuss the evidence for collision based transfer in miniemulsion polymerization and also consider whether collision based monomer transport can play a role in regular emulsion polymerizations.

Anticancer, antioxidant, and antimicrobial activities of nanoemulsions based on water-in-olive oil and loaded on biogenic silver nanoparticles

Abstract Nanoemulsions (NEMs) are more stable and permeable than regular emulsions because of their increased surface area and smaller particle sizes, which are stabilized by emulsifiers and consist of nanometer-sized droplets. Utilization of an olive oil nanoemulsion (NEM-olive oil) loaded with silver nanoparticles (Ag-NPs) derived from marine alga Turbinaria turbinata may be effective against microorganisms and cancer cell lines. NEM-olive oil was made by mixing olive oil, surfactant (Span:Tween (28:72)), and D water (1:4:5). The marine alga Turbinaria turbinata was used for the synthesis of Ag-NPs (Tu-Ag-NPs), and combined with NEM-olive oil (1:1) to synthesize Ag-NPs loaded in olive oil–water nanoemulsion (Ag/NEM-olive oil). Transmission electron microscopy, energy-dispersive X-ray analysis, zeta potential, Fourier transform infrared, and X-ray powder diffraction spectroscopy were used to characterize the nanoparticles. Both NEM-olive oil and Ag/NEM-olive oil nanoparticles showed a negative surface charge and small diameter. The major components of NEM-olive oil are dodecanoic acid, 2-penten-1-yl ester, 9-octadecenoic acid, and oleic acid. All tested nanoparticles exhibited anticancer activity against the CACO-2 cell line and Hep G2, and antimicrobial activities against E. faecalis, S. aureus, E. coli, and C. albicans. The present research suggested that olive oil NEM loaded with marine algae Ag-NPs can be a safe and economical anticancer, antimicrobial, and drug delivery.

Biofunctional features of Pickering emulsified film from citrus peel pectin/limonene oil/nanocrystalline cellulose

SummaryThe application of edible films can be an alternative solution for maintaining the quality of post‐harvest horticultural commodities. This study aimed to determine the effect of adding a stabiliser, cellulose nanocrystals (CNCs), on the functional characteristics of citrus peel pectin and limonene essential oil (LEO)‐based coatings. A formulation comprising pectin (0.5%), CNC (0.075%) and LEO (0.5%) was prepared. The CNC morphology (nanometre scale) was nanorods with pointed ends on both sides, revealed with atomic force microscopy. Gas chromatography–mass‐spectrometry verified the main component of LEO, d‐limonene. All prepared film‐forming solution showed good stability with zeta potential values ranging from −76.34 to −35.33 mV. The developed film had a rougher surface due to the presence of oil aggregates and CNC agglomeration during film preparation. The addition of Pickering emulsion showed improvements in terms of mechanical properties (tensile strength 23.61 MPa, and elongation 65.87%), water barrier and the film clarity compared with regular emulsions with synthetic surfactants. It effectively inhibited the growth of harmful microbes that cause the rotting of fresh fruits, i.e., Penicilium digitatum, by 3.87% and 14.83% compared to the conventional emulsion and pectin‐based film, respectively, through the well diffusion test method. Thus, the combination of pectin/CNC/LEO can be used as an alternative active coating for fresh fruit commodities.

An Overview on Microemulsion as a Topical Drug Delivry System

Due to their extended shelf life, enhanced drug solubilization, and simplicity in preparation and administration, microemulsions are among the greatest possibilities for new drug delivery systems. Microemulsions are liquid mixtures of amphiphile, water, and oil that are thermodynamically stable and optically isotropic. They have become cutting-edge drug delivery systems that enable controlled or sustained release for parenteral, ophthalmic, percutaneous, topical, and transdermal medication administration.Because of their low viscosity, transparency, and, more precisely, their thermodynamic stability, microemulsions may be easily distinguished from regular emulsions. Microemulsions have a wide range of uses and applications, including in the pharmaceutical, agrochemical, cutting oil, biotechnology, food, and cosmetic industries as well as in analytical applications and environmental detoxification. This review paper's main goal is to talk about using microemulsions as a medicine delivery mechanism with other potential uses.

Characterization of fatigue performance of cold mix recycled asphalt mixtures through uniaxial tension–compression testing

Cold recycling of pavements utilizes nearly 100% of the reclaimed asphalt pavement (RAP) for pavement rehabilitation. Due to the large amount of RAP, the cold recycled mixes would become prone to fatigue cracking, and hence evaluation of their fatigue performance becomes highly important. In this study, three cold recycled asphalt mixes were prepared using a regular cationic slow setting asphalt emulsions with hard base asphalt binder (CSS-1h) with and without Portland cement stabilization, and a polymer modified emulsion (CSS-1hp). The optimum emulsion and pre-mix water contents were determined using Superpave Gyratory compacted specimens through the mix design process by studying the air void levels and meeting minimum strength requirements. Fatigue properties of these three groups of mixes were then evaluated through a series of uniaxial cyclic tension–compression tests. The results were compared in terms of the modulus degradation, dissipated energy capacity, changes in phase angle, and number of cycles to failure, to determine the fatigue lives of the different mixes. The results indicated that adding 1% Portland cement to the cold recycled specimens significantly improved their fatigue performance as compared to the control scenario specimens prepared with regular CSS-1h emulsion. Using the polymer modified emulsion also led to a slightly improved fatigue resistance of the cold mix specimens as compared to the mixes prepared with regular emulsion. Furthermore, Multiple Stress Creep Recovery (MSCR) testing of the two residual emulsion binders indicated potential of improving the rutting resistance for the mixes prepared with the polymer modified emulsion.

Antifungal features and properties of chitosan/sandalwood oil Pickering emulsion coating stabilized by appropriate cellulose nanofiber dosage for fresh fruit application

A novel composite edible coating film was developed from 0.8% chitosan (CS) and 0.5% sandalwood oil (SEO). Cellulose nanofibers (CNFs) were used as a stabilizer agent of oil-in-water Pickering emulsion. We found four typical groups of CNF level-dependent emulsion stabilization, including (1) unstable emulsion in the absence of CNFs; (2) unstable emulsion (0.006–0.21% CNFs); (3) stable emulsion (0.24–0.31% CNFs); and (4) regular emulsion with the addition of surfactant. Confocal laser scanning microscopy was performed to reveal the characteristics of droplet diameter and morphology. Antifungal tests against Botrytis cinerea and Penicillium digitatum, between emulsion coating stabilized with CNFs (CS-SEOpick) and CS or CS-SEO was tested. The effective concentration of CNFs (0.24%) may improve the performance of CS coating and maintain CS-SEO antifungal activity synergistically confirmed with a series of assays (in vitro, in vivo, and membrane integrity changes). The incorporation of CNFs contributed to improve the functional properties of CS and SEO-loaded CS including light transmission at UV and visible light wavelengths and tensile strength. Atomic force microscopy and scanning electron microscopy were employed to characterize the biocompatibility of each coating film formulation. Emulsion-CNF stabilized coating may have potential applications for active coating for fresh fruit commodities.

Kinetics of MMA Atom Transfer Radical Polymerization Initiated by Reducing Agent in Stirred Batch Emulsion Reactor

AbstractAb initio emulsion atom transfer radical polymerization (ATRP) differs from regular emulsion polymerization because the kinetic and thermodynamic aspects of each process are very unlikely alike. This paper presents a kinetic analysis of activator generated by electron transfer (AGET) ATRP of methyl methacrylate (MMA) in a stirred emulsion reactor. The focus of the study is to assess the variation of the monomer content in the organic phase and the rate polymerization for different reaction temperatures, as well as the impact of surfactant content and stirring speed on latex stability. Poly(methyl methacrylate) (PMMA) polymer samples are analyzed by means of gravimetry, dynamic light scattering, gel permeation chromatography, and HNMR techniques to determine monomer conversion, polymer particle diameter, molecular weight distribution, and polymer molecular structure, respectively. The results show the production of PMMA of narrow polydispersity index (Ð) and low molar mass (Mn) for MMA conversion around 60% and detect two‐regions instead of a three‐regions trend of rate of polymerization (Rp) as conventional emulsion polymerization. The reaction rate increases during the nucleation stage and then flattens over an invariant trend which confirms a living feature of the AGET ATRP polymerization. The average number of radicals per latex particle (ñ) is also debated.

Investigation of the stability in Pickering emulsions preparation with commercial cosmetic ingredients

In recent years, the use of Pickering emulsions in topical formulation has received growing interest from academics to cosmetic and pharmaceutical industries. Compared to regular emulsions stabilized with synthetic low molecular weight surfactants, Pickering emulsions avoid the use of hazardous surfactants and show improved stability, making them as new targeting systems in cosmetic and pharmaceutical products. However, most of the studies on Pickering emulsions were performed with non-biocompatible model oils such as toluene, n-dodecane or hexadecane. For a cosmetic or pharmaceutical application, the change for a biocompatible oil is necessary, but this often induces dramatic changes or modifications in the emulsion stability. Therefore, in this work, we try to fill the gap by applying the discovered rules drew from previous reported model studies to the Pickering systems of industrial cosmetic ingredients. In particular, we investigate the stability in Pickering emulsions produced from biocompatible oils including, silicone and ester-based oils that are commonly used in personal care products. Our result shows that the resultant emulsions preparation with biocompatible oils and stabilized with commercial fumed silica particles follow a rule that derived from our model study. Wettability of particles are discussed to predict the emulsion type and their stability during storage. The findings in this study will provide a practical guide to researchers to better understand the emulsion properties produced from commercial cosmetic ingredients and advance their possible industrial applications.

A PREPARATION, CHARACTERIZATION, AND IN VITRO SKIN PENETRATION OF MORUS ALBA ROOT EXTRACT NANOEMULSION

Objective: White mulberry (Morus alba) root extract has terpenoid, flavonoid, and stilbene compounds. The stilbenes, oxyresveratrol and resveratrol, have antioxidant and antityrosinase activities. Nanocarriers can help active ingredients to be delivered in a more efficient manner. The advantages of nanoemulsion on products include increased penetration, biocompatibility, and low toxicity due to its non-ionic properties and have the ability to combine the properties of lipophilic and hydrophilic active ingredients. The objective of this study was to prepare, characterize, and evaluate the in vitro skin penetration of M. alba root extract nanoemulsion.
 Methods: The M. alba root extract was prepared by ionic liquid-based microwave-assisted extraction method. Nanoemulsion was optimized and prepared using virgin coconut oil (VCO), Tween 80, and polyethylene glycol 400 (PEG 400) by aqueous phase-titration method to construct pseudoternary phase diagram. M. alba root extract nanoemulsion was characterized for droplet size, viscosity, zeta potential, and physical stability tests for 12 weeks. In vitro skin penetration of oxyresveratrol from nanoemulsion was determined by the Franz diffusion cell and was compared by macroemulsion preparation, then analyzed by high-performance liquid chromatography method.
 Results: Based on pseudoternary phase diagram, nanoemulsion of white mulberry root extract contained of 2% VCO and 18% mixture of surfactant Tween 80 and PEG 400 (1:1) was chosen. Nanoemulsion has average globule size of 81.61 nm, with polydispersity index 0.22, and potential zeta −1.56 mV. The cumulative penetration of oxyresveratrol from nanoemulsion was 55.86 μg/cm2 with flux of 6.53 μg/cm2/h, while regular emulsion was 32.45 μg/cm2 with flux of 3.5501 μg/cm2/h.
 Conclusion: Nanoemulsion of white mulberry root extract was penetrated deeper than regular emulsion.

Preparation of polylactide microcapsules at a high throughput with a packed‐bed premix emulsification system

ABSTRACTCore–shell polymer microcapsules are well known for their biomedical applications as drug carriers when they are filled with drugs and gas‐filled microcapsules that can be used as ultrasound contrast agents. The properties of microcapsules are strongly dependent on their size (distribution); therefore, equipment that allows the preparation of small and well‐defined microcapsules is of great practical relevance. In this study, we made polylactide microcapsules with a packed‐bed premix emulsification system that previously gave good results for regular emulsions. Here, we tested it for applicability to a system in which droplets shrank and solidified to obtain capsules. The packed‐bed column was loaded with glass beads of different sizes (30–90 µm) at various bed heights (2–20 mm), and coarse emulsions consisting of the polymer, a solvent, and a nonsolvent were pushed repeatedly through this system at selected applied pressures (1–4 bar). The obtained transmembrane fluxes (100–1000 m3 m−2 h−1) were much higher than those recorded for other membrane emulsification techniques. The average size of the obtained microcapsules ranged between 2 and 8 µm, with an average span of about 1; interestingly, the capsules were 2–10 times smaller than the interstitial voids of the beds. The droplets were larger when we used thicker beds and larger glass beads, and these effect correlated with the pore Reynolds number (Rep). Two breakup mechanisms were identified: spontaneous droplet snap‐off dominated the system at low Reps, and localized shear forces dominated the system at higher Rep. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43536.

Physico chemical, microstructural and sensory characteristics of low‐fat meat emulsion containing aloe gel as potential fat replacer

SummaryIn this study, a possible use of aloe gel (AG) as a potential fat replacer in the manufacture of low‐fat meat emulsion was investigated. The low‐fat meat emulsions with added AG and vegetable oil (VO) in different proportions [AG7.5 (7.5% AG + 7.5% VO); AG5 (5% AG + 10% VO); AG2.5 (2.5% AG + 12.5% VO)] were compared with full‐fat meat emulsion [Control (15% VO only)]. A substantial fat reduction (P < 0.05) up to 50% as compared to full‐fat control meat emulsion was recorded without compromising other sensory attributes of meat emulsion. Microstructural properties as studied by scanning electron microscopy indicated more homogenous regular emulsion matrix with fewer cracks and more regular shaped oil droplets in AG‐added samples than the control samples.

Nanoemulsion through cold emulsification: An advanced cold manufacturing process for a stable and advanced drug delivery system

The personal care and pharmaceutical industries use emulsion science and its by-products extensively to create creams and lotions that include both water and oil-soluble ingredients. Although it is predicted that cooling and heating alone account for over 90% of the overall expenditure of energy used for the manufacture of an emulsion system, present methods for processing such emulsions demand large amounts of time and energy. The cold process of emulsion technologies will become more preferable to consumers and consumer has started showing interest in sustainable and environment-friendly products and procedures. An advanced cold emulsification method of manufacturing a topical semisolid dosage form has been developed for an advanced drug delivery system in the form of nanoemulsion to overcome the manufacturing challenges of thermolabile drugs and to have a sustainable and eco-friendly cost-effective drug delivery when compared to conventional topical dosage forms. The creation of nanoemulsions will result in a formulation that is thermodynamically stable and combines two immiscible liquids to create a stable homogenous combination in the presence of an appropriate stabilizer. The stability and droplet size of a nanoemulsion makes it different from a regular emulsion; the smaller droplet size increases its stability and penetration through the skin’s epidermis. In this review, the emphasis is on providing a basic understanding of cold emulsification as a formulation technique for nanoemulsions, its characterization, applications, and various patents and clinical trials involving nanoemulsions. This information can serve as the foundation for further developing and improving current techniques and technology involving nanoemulsions.

Controlled preparation of porous polysulfone monolith via concentrated emulsion templating using an aminated polysulfone as surfactant

AbstractA methodology for preparing porous polysulfone (PSF) monolith via concentrated emulsion templating was proposed. A regular emulsion was first prepared using a solution of PSF in chloroform as the continuous phase and deionized water as the dispersed one. After the emulsion was formed, the liquid species in the emulsion was allowed to be evaporated. The solvent chloroform was first removed and the emulsion was transformed to a concentrated emulsion. Further removing the aqueous species, a porous PSF monolith was obtained. To keep the system stable throughout the process, an aminated polysulfone rather than conventional surfactants was employed. The effects of chloroform and water fractions, the nature and loading of the macromolecular surfactant, the evaporating temperature on the pore structure were investigated. Controlled porous structure with different pore size and porosity could be obtained through the method. POLYM. ENG. SCI., 2011. © 2010 Society of Plastics Engineers.

Feasibility of surfactant-free supported emulsion liquid membrane extraction

Supported emulsion liquid membrane (SELM) is an effective means of conducting liquid-liquid extraction. SELM extraction is particularly attractive for separation tasks in the microgravity environment where density difference between the solvent and the internal phase of the emulsion is inconsequential and a stable dispersion can be maintained without surfactant. In this research, dispersed two-phase flow in SELM extraction is modeled using the Lagrangian method. The results show that the SELM extraction process in the microgravity environment can be simulated on earth by matching the density of the solvent and the stripping phase. The feasibility of surfactant-free SELM (SFSELM) extraction is assessed by studying the coalescence behavior of the internal phase in the absence of the surfactant. Although the contacting area between the solvent and the internal phase in SFSELM extraction is significantly less than the area provided by regular emulsion due to drop coalescence, it is comparable to the area provided by a typical hollow-fiber membrane. Thus, the stripping process is highly unlikely to become the rate-limiting step in SFSELM extraction. SFSELM remains an effective way of achieving simultaneous extraction and stripping and is able to eliminate the equilibrium limitation in the typical solvent extraction processes. The SFSELM design is similar to the supported liquid membrane design in some aspects.

Reversible Invert Emulsion Drilling Fluids: A Quantum Leap in Technology

Summary A novel, invert emulsion fluid useful in the drilling, completion, and workover of subterranean wells has been invented. The new invert emulsion drilling fluid can readily and reversibly be converted from an invert, i.e., water-in-oil emulsion, to a regular, i.e., oil-in-water emulsion, and back to the original invert emulsion using an acid-base chemical switch. The surfactants used in the reversible invert emulsion fluids are strong invert emulsifiers in the presence of lime. However, the same surfactants become regular emulsifiers in the presence of water-soluble acid. The reversible emulsion property of these surfactants allows the drilling fluid to be changed from an invert emulsion to a regular emulsion at different stages of the drilling/completion operation. During the drilling stage, the drilling fluid can be an invert emulsion achieving all the performance benefits associated with oil-based muds (OBMs). During the completion stage and afterwards, the emulsion can be reversed by adding water-soluble acid, thus providing excellent filtercake cleanups, improved production in an openhole completion, better cementing, and efficient cuttings cleanup and waste minimization. The reversible system is simple and easy to run without any exotic changes in current operations or other additives than those commonly used in OBMs. The reversible drilling fluid is versatile and relatively inexpensive and versatile, especially as compared to new, exotic fluids on the market today. The reversible feature allows the mud to achieve performance, production, minimal environmental impact, and cost control. The paper discusses the overall impact of reversible invert emulsion technology in meeting the environmental and functional requirements of drilling operations. The laboratory data show that this system can provide drilling performance similar to OBMs at various oil/water (O/W) ratios, mud weights, and in the presence of commonly encountered contaminants. This paper compares the new reversible fluids with previous state-of-the-art invert emulsion drilling fluids. These new stable, reversible invert emulsion drilling fluids can readily be reversed to regular emulsions using inorganic acids such as hydrochloric acid or organic acids such as citric acid. The paper discusses the application of reversible emulsion technology on efficient removal of filter cake and improved production in openhole horizontal well completions. The environmental impacts of this system on washing and disposal of drilled cuttings are discussed.

A liquid crystal application in skin care cosmetics

Intercellular lipids of the stratum corneum contribute threefold to the maintenance of a healthy skin: by hydration, cell adhesion, and reduction of transepidermal water loss. All of these functions can be attributed to the self-organizing property of the amphiphilic molecules of the stratum corneum lipids. A new type of skin care product called Lamellar Gel was developed, which contains a (synthesized) pseudo-ceramide. Its structure is similar to that of ceramide found among the stratum corneum lipids, which allows it to control intramolecular interactions. Compared to regular emulsions the Lamellar Gel demonstrated better skin care characteristics regarding permeability, skin hydration, and skin occlusion. This was attributed to the fact that it formed the same self-organizing structure as natural stratum corneum lipids, hence showing a high affinity to the skin. A high moisturizing effect was observed as the Lamellar Gel combines the benefits of both O/W and W/O emulsions: it provides the same initial hydration as an O/W emulsion and at the same time the same occlusivity as a W/O emulsion. Transepidermal water loss increases under dry environmental conditions. This especially affects the skin around the eyes, where the skin is very thin, and wrinkles are very easily formed. Treatment with the Lamellar Gel recovered these wrinkles promptly and hydrated the stratum corneum for a long time.