Distinctive rheological properties of Pickering emulsions: from their origin to the applications

Lee EunSuk,김동권,김규한 한국유변학회 2022 Korea-Australia rheology journal Vol.34 No.2

Pickering emulsion, which is stabilized by colloidal particles, has shown great promise in various fields due to its great stability and processibility. Depending on the type, size, number of colloidal particles, volume fraction of the dispersed phase, and emulsification method, various Pickering emulsions with different internal structures can easily be produced. Furthermore, according to the internal structure, the considerably different rheological properties can be achieved, from Newtonian viscous-like response to Hookean solid-like response. This strongly suggests that the rheological properties of Pickering emulsions can be tuned, especially for specific applications. In this paper, we summarize the progress in the measurement and understanding of the rheological properties of Pickering emulsions. We also categorize them into three different sections, depending on the volume fraction of the dispersed phase. Furthermore, we introduce the applications of Pickering emulsions that have recently become popular due to their distinctive rheological properties.

화장품 에멀젼: 입자에 의한 안정화

조완구 ( Cho Wan Goo ) 대한화장품학회 2010 대한화장품학회지 Vol.36 No.1

본 총설에서는 나노미터 크기의 고체 입자가 오일-물 계면에 흡착됨으로써 안정화된 에멀젼의 제조와 성질에 대하여 기술하였다. 이렇게 제조된 에멀젼을 Pickering 에멀젼이라 하며 이 에멀젼을 계면활성제로 안정화된 일반적인 에멀젼과 비교하였다. Pickering 에멀젼의 독특한 성질은 입자의 계면 흡착 에너지가 큰 점에 기인하며 일반 에멀젼과 주요한 차이점은 고체 입자가 비가역적으로 계면에 흡착한다는 사실이다. Pickering 에멀젼의 전상은 w/o (waterin-oil) 타입에서 o/w (oil-in-water)로 수상의 분율이 증가함에 따라 발생한다. 친수성의 입자는 o/w 에멀젼을 형성하는 경향을 보이고 친유성 입자는 w/o 에멀젼을 형성하는 경향을 보이며 이는 고체 입자의 오일-물 계면에서의 접촉각에 따른다. Pickering 에멀젼의 안정성은 많은 부분에서 일반적인 에멀젼과는 다른 거동을 보였다. 저자는 또한 Pickering 에멀젼의 화장품 응용 가능성에 대해서도 논의하였다. The preparation and properties of emulsions stabilized by the adsorption of solid particles at the oil-water interface are reviewed. Comparison is made with the behaviour of surfactant-stabilized emulsions. Many of the properties of Pickering emulsions are attributed to the large free energy of adsorption for particles. The main differences is due to the irreversible adsorption of particles to the interface. Phase inversion from w/o (water-in-oil) to o/w (oil-in-water) can be brought by increasing the volume fraction of water. Hydrophilic particles tend to form o/w emulsion whereas hydrophobic particles form w/o emulsion. The contact angle at the oil-water interface is main parameter to decide the emulsion type. The aspects of stability of Pickering emulsions are in contrast to general emulsions in some points. The possibility using Pickering emulsions for cosmetics is also proposed.

Diblock copolymer worms stabilized pH-responsive Pickering emulsions: An efficient and recyclable platform for Claisen-Schmidt condensation reaction

Zhe Xiang,Xi Zhao,Guoxiang Wang,Chenze Qi,Sujing Zhou,Jinjing Li,Yong Gao 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.117 No.-

Pickering emulsions were promising platforms for the heterogeneous reactions due to both their largeinterfacial areas and high stability, whereas both the product separation and the emulsifier recoveryvia simple and efficient strategies for remain a concern. In this study, we constructed an efficient andrecyclable platform for interfacial catalytic reaction adopting pH-responsive n-decane-in-waterPickering emulsions. Pickering emulsions were prepared employing core cross-linked PEO45-PGMA74(CCE45G74) diblock copolymer worms as Pickering emulsifiers. CCE45G74 diblock copolymer worms wereprepared via the combination of photo-initiated polymerization induced self-assembly strategy and thecore covalent cross-linking with ethylenediamine. The prepared n-decane-in-water Pickering emulsionsshowed a high stability during the storage at the room temperature, whereas a rapid demulsification tookplace at a lower pH, such as 2.5. Alkali-catalyzed Claisen-Schmidt condensation reactions between benzaldehydeand acetone were conducted in n-decane-in-water Pickering emulsions at 30 C. The yield ofdibenzylidene acetone could reach 99% after 12 h of reaction. The reaction efficiency was far higher thanthat at the plain n-decane-water (30%). This catalytic platform could be repeatedly used for three cycles

Characterization of SPN Pickering emulsions for application in enhanced oil recovery

Narendra Kumar,Tushar Gaur,Ajay Mandal 한국공업화학회 2017 Journal of Industrial and Engineering Chemistry Vol.54 No.-

Emulsion, stabilized by solid particles that get adsorb on to the surface of the interface is known as Pickering emulsion, which has potential application in enhanced oil recovery (EOR). In present study, a stable oil-in-water surfactant–polymer–nanoparticle (SPN) Pickering emulsion has been formulated using light mineral oil, carboxy methyl cellulose (CMC) and silica nanoparticles (SiO2) in presence of anionic surfactant, for use in EOR. The nanoparticles (NPs) show synergetic effect in presence of surfactant and polymer thus prevents the droplets from coalescence and lowers the interfacial tension (IFT) at the oil–water interface. The emulsion was characterized in terms of particle size, creaming behavior and zeta potential measurements. The viscosity remains stable in wide range temperature (30– 100 C) indicating thermal stability of the Pickering emulsion. The emulsion exhibits pseudo-plastic behavior in wide range of shear rate (1–1000 s1). The investigation of viscoelastic properties (G0 and G00) of the Pickering emulsion as a function of pressure (0–5 MPa) and temperature (30–100 C) shows a stable value of G00 indicating better flow ability of the emulsion. The emulsions show viscous behavior below the specific frequency (SF) indicated by the crossing point between G0 and G00 on the viscoelastic curve and elastic behavior above the SF. Flooding experiment was conducted on sand pack system to study the efficiency of Pickering emulsion in EOR and additional recovery of more than 24% was observed after conventional water flooding.

Viscosity of the oil-in-water Pickering emulsion stabilized by surfactant-polymer and nanoparticle-surfactant-polymer system

Tushar Sharma,G. Suresh Kumara,전보현,Jitendra S. Sangwai 한국유변학회 2014 Korea-Australia rheology journal Vol.26 No.4

Information on the viscosity of Pickering emulsion is required for their successful application in upstreamoil and gas industry to understand their stability at extreme environment. In this work, a novel formulationof oil-in-water (o/w) Pickering emulsion stabilized using nanoparticle-surfactant-polymer (polyacrylamide)system as formulated in our earlier work (Sharma et al., Journal of Industrial and Engineering Chemistry,2014) is investigated for rheological stability at high pressure and high temperature (HPHT) conditionsusing a controlled-strain rheometer. The nanoparticle (SiO2 and clay) concentration is varied from 1.0 to 5.0wt%. The results are compared with the rheological behavior of simple o/w emulsion stabilized by surfactant-polymer system. Both the emulsions exhibit non-Newtonian shear thinning behavior. A positive shiftin this behavior is observed for surfactant-polymer stabilized emulsion at high pressure conditions. Yieldstress is observed to increase with pressure for surfactant-polymer emulsion. In addition, increase in temperaturehas an adverse effect on the viscosity of emulsion stabilized by surfactant-polymer system. In caseof nanoparticle-surfactant-polymer stabilized o/w emulsion system, the viscosity and yield stress are predominantlyconstant for varying pressure and temperature conditions. The viscosity data for both o/w emulsionsystems are fitted by the Herschel-Bulkley model and found to be satisfactory. In general, the studyindicates that the Pickering emulsion stabilized by nanoparticle-surfactant-polymer system shows improvedand stable rheological properties as compared to conventional emulsion stabilized by surfactant-polymersystem indicating their successful application for HPHT environment in upstream oil and gas industry.

Effect of Colloidal Jamming in Continuous Phase on the Elasticity of High Internal Phase Pickering Emulsions

채준수,최시영 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.1

High internal phase emulsions, which their volume fraction of dispersed phase is over 74%, show solid like property because of their tremendous interfacial area. Many researches tried to explain the rheological properties of HIPEs, however, most of them are for the surfactant emulsions. In the case of Pickering HIPEs, higher G’ values were obtained compared to surfactant HIPEs but there is no clear explanation for this yet. In this study, we studied how colloidal particles attributed to the emulsion rheology. By measuring the rheological properties of continuous phase which is colloidal suspension, we could validate that colloidal suspension in confined geometry between two droplets brought larger G’ of Pickering HIPEs. By reducing gap of parallel plates of rheometer, we could observe the effect of confinement on rheological properties of colloidal suspensions and figured out that liquid to solid transition can occur without changing volume fraction or temperature.

Thermal stability of oil-in-water Pickering emulsion in the presence of nanoparticle, surfactant, and polymer

Sharma, T.,Kumar, G.S.,Chon, B.H.,Sangwai, J.S. Korean Society of Industrial and Engineering Chemi 2015 Journal of industrial and engineering chemistry Vol.22 No.-

Pickering emulsion offers potential applications in several fields including oil and gas industry due to their enhanced stability. Oil-in-water (o/w) emulsions are usually stabilized by surfactant or nanoparticle or by both but show poor thermal stability which limits their use for high-temperature applications. In this work, a novel formulation of o/w emulsion stabilized using nanoparticle-surfactant-polymer system is investigated for the formulation of thermally stable Pickering emulsion. The conventional oilfield polymer polyacrylamide (PAM), surfactant, sodium dodecylsulfate (SDS), and nanoparticles such as, SiO<SUB>2</SUB>, clay, and CuO in varying concentration are used. It is observed that the nanoparticle in the presence of surfactant and polymer synergistically interacted at the oil-water interface. The effect of temperature, pH, and salinity on the interfacial tension is investigated to understand the thermal stability. The emulsion system with partially hydrophobic clay nanoparticles in the presence of PAM and SDS shows higher thermal stability as compared to fully hydrophilic SiO2 nanoparticles. In the presence of salt, NaCl (1.0wt%), the thermal stability of clay and SiO2 stabilized emulsions is observed to be further promoted at higher temperatures. Scanning electron microscopy (SEM) images confirm the existence of a structured and rigid layer of nanoparticle at the oil-water interface.

Nanoemulsion drops-attached Pickering emulsions by amphiphilically modified biocellulose nanofibrils

서혜민,신경희,박예진,서민정,김진웅 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.0

This study introduces a novel nanoemulsion drop-attached Pickering emulsion system, in which the oil in water interface was stabilized by amphiphilically modified biocellulose nanofibrils (AMBCs). We first modified the surface of hydrophilic BCs to impart the hydrophobicity and to induce DNA interaction. For this, octadecylamine and amine terminated DNA were grafted onto fully-oxidized BCs that were treated with 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide and N-hydroxysuccinimide to form amide bonds. The AMBCs as emulsifier reduced the surface tension. This facilitated to fabricate a stable Pickering emulsion with improved viscosity. The interface adsorbed by the AMBCs was confirmed by fluorescence microscopy. Finally, we attached attractive nanoemulsion drops to the Pickering emulsion through hydrogen bonding interaction. The attractive nanoemulsion was functionalized by DNA sequence to interact with a pair of the DNA sequence in the water-phase of Pickering emulsion.

난연제-파라핀 피커링 에멀젼 제조 및 주입 목재의 연소특성과 치수안정성

박순,이종신,정재희,윤선미,김진경 한국가구학회 2023 한국가구학회지 Vol.34 No.3

. Paraffin wax treated wood has high dimensional stability against water. However, due to the flammable property of paraffin wax, it has a problem that it is weak against fire. In or- der to have flame retardant properties in paraffin wax-treated wood, a Pickering emulsion was prepared using a wood flame retardant and paraffin wax, and the combustibility and dimen- sional stability of the treated wood was investigated, and the following conclusions were reached. A stabilized paraffin Pickering emulsion that does not phase separate from water can be prepared by adding 5 wt.% paraffin wax to the nano-silica dispersion solution and homoge- nizing it. Wood impregnated with a paraffin Pickering emulsion prepared from a nano-silica dispersion containing a flame retardant component can expect flame retardant properties almost the same as wood impregnated with only flame retardant solution. The effect of improving the dimensional stability of wood was not obtained by the paraffin Pickering emulsion im- pregnation, and in order to increase the dimensional stability in addition to flame retardant property, it is necessary to develop a Pickering emulsion manufacturing technology capable of increasing the amount of paraffin wax.

Bacterial cellulose nanofibrils-armored Pickering emulsions with limited influx of metal ions through the oil-water interface

서혜민,김진웅 한국공업화학회 2020 한국공업화학회 연구논문 초록집 Vol.2020 No.-

This study introduces a novel UV-blocking Pickering emulsion system of which solid interface consisted of a bacterial cellulose nanofibril (BCNF) surfactant. For this, we prepared TEMPO-oxidized BCNFs and their surface was hydrophobically modified by covalently grafting controlled amounts of C18 alkyl chains. We observed that this BCNF surfactant reduced the surface tension while forming a cellulose membrane at the oil-water (O/W) interface. This cellulose membrane stabilized Pickering emulsion by armoring oil drops. The BCNF surfactant was feasible to emulsify up to 40 vol% of oil. We showed that the BCNFs were able to entrap metal ions by electrostatic binding between BCNFs and metal ions which is essential for the emulsion to maintain UV-blocking performance. Finally, we expect that the BCNFs fabricated in this study would have great applicability either for development of a variety of cellulose surfactant or for the application of UV-blocking Pickering emulsions.