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Pickering emulsion

Laura Sawiak, Katherine Bailes, David Harbottle, Paul S Clegg
It has previously been demonstrated that particle-stabilized emulsions comprised of limonene, water and fumed silica particles exhibit complex emulsification behavior as a function of composition and the duration of the emulsification step. Most notably the system can invert from being oil-continuous to being water-continuous under prolonged mixing. Here we investigate this phenomenon experimentally for the regime where water is the majority liquid. We prepare samples using a range of different emulsification times and we examine the final properties in bulk and via confocal microscopy...
2018: Frontiers in Chemistry
Heba Elmotasem, Hala K Farag, Abeer A A Salama
The objective of this study was to innovate an effective oral sustained release hepatoprotective formula for - the water soluble drug - caffeine. Caffeine is rapidly absorbed and eliminated which dictates frequent administration to achieve adequate therapeutic effect. A w/o Pickering emulsion incorporating caffeine in the internal phase was primed. It contained wheat germ oil and was stabilized by synthesized magnesium oxide nanoparticles (MgO NPs). Components selection was based on their antioxidant, hepatoprotective and anticarcinogenic effects...
May 16, 2018: International Journal of Pharmaceutics
Xiaoguang Qiao, Pierre-Yves Dugas, Laurent Veyre, Elodie Bourgeat-Lami
We report an efficient and easy to implement waterborne sol-gel process for the synthesis of nanometric organosilica particles. In this process, tetraethyl orthosilicate (TEOS) and 3-(methacryloxy)propyl trimethoxy silane (γ-MPS), employed as silica sources, are heterogeneously delivered in an aqueous solution of L-arginine, a basic amino acid used as catalyst, from a top organic layer. Co-condensation of TEOS with γ-MPS led to organosilica particles with diameters comprised between 30 and 230 nm when increasing the γ-MPS content from 0 to 10...
May 18, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Man-Hin Kwok, To Ngai
Pickering emulsions prepared by various kinds of soft colloids such as the poly( N -isopropylacrylamide) (PNIPAM)-based microgels, have been studied for decades in order to fabricate stimuli-responsive emulsions. It has been generally viewed that the interfacial properties of the microgel monolayers and the emulsion stability are dominated by the softness or deformability of the microgel particles. However, there is still no convenient way to characterize the adsorption/desorption energy of the microgels at the interface although this is an essential topic for microgel-stabilized emulsions...
2018: Frontiers in Chemistry
Roxana-Elena Avrămescu, Mihaela-Violeta Ghica, Cristina Dinu-Pîrvu, Denisa Ioana Udeanu, Lăcrămioara Popa
Liquid marbles are versatile structures demonstrating a pseudo-Leidenfrost wetting regime formed by encapsulating microscale volumes of liquid in a particle shell. The liquid core is completely separated from the exterior through air pockets. The external phase consists of hydrophobic particles, in most cases, or hydrophilic ones distributed as aggregates. Their interesting features arise from the double solid-fluid character. Thus, these interesting formations, also known as “dry waters”, have gained attention in surface science...
May 9, 2018: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Yanan Wang, Wenhang Wang, Hongjiao Jia, Guixian Gao, Xiao Wang, Xiaowei Zhang, Yabin Wang
Nano cellulose is attracting great interest in food and nutraceutical fields and also provides a potential additive to develop functional meat products such as low fat sausage. Here, we compared 1 wt% aqueous dispersion of cellulose nanofiber (CNF) and its palm oil Pickering emulsion (CPOE) at the ratio of 1:1 (water: oil, v:v) for being fat alternatives replacing 30% and 50% of the original fat of the emulsified sausage. Replacing fat by CPOE and CNF resulted in lower fat content, lower cooking loss and higher moisture content and higher lightness values (P ≤ 0...
May 10, 2018: Journal of Food Science
Shuyue Guo, Yanan Jiang, Fei Wu, Ping Yu, Huibiao Liu, Yuliang Li, Lanqun Mao
As a new kind of two-dimensional carbon allotrope, graphdiyne (GDY) consists of sp- and sp2 -hybridized carbon atoms and has recently been used for developing highly efficient photocatalytic systems because of its unique properties. In this study, we find that GDY can form a Pickering emulsion with silver phosphate (Ag3 PO4 ) nanoparticles that exhibits largely enhanced photocatalytic activity in the visible-light region. In this system, Ag3 PO4 acts as a photocatalytically active semiconductor with GDY as the hydrophobic nanostructure...
May 10, 2018: ACS Applied Materials & Interfaces
Dalin Wu, Andrei Honciuc
Elucidating the mechanisms responsible for spontaneous adsorption of nanoparticles (NPs) at interfaces is important for their application as emulsifiers, bubble stabilizers or foaming agents. In order to investigate the key factors that control spontaneous adsorption of NPs at Liquid-Liquid interfaces, we synthesized seven different types of NPs from pH-responsive polymers poly(2-(diethylamino)ethyl methacrylate) (PDEAEMA) and poly(2-dimethylamino)ethyl methacrylate) (PDMAEMA) via surfactant-free emulsion polymerization or via "grafting from" polystyrene (PS) NPs...
May 5, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Na Song, Ai-Juan Wang, Jun-Ming Li, Zhuo Zhu, Huijun Shi, Xiao-Long Ma, Dejun Sun
Emulsions were prepared using hydroxyapatite nanoparticles and nonionic surfactant sorbitan monooleate (Span 80) as emulsifier. Effects of Span 80 concentration, emulsification time, emulsification rate, poly(l-lactic acid) (PLLA) concentration and the surface chemical properties of hydroxyapatite nanoparticles on emulsion properties were systematically studied. The results showed that emulsion would undergo a phase inversion from oil-in-water (O/W) type to water-in-oil (W/O) type with an increase in Span 80 concentration...
May 4, 2018: Soft Matter
Xin Zhou, Changyou Chen, Changyan Cao, Tao Song, Hengquan Yang, Weiguo Song
Pickering emulsion is emerging as an advanced platform for catalysis because of the large oil/water interface area for reaction and its superior efficiency. How to enhance the mass transportation within the micro-droplets is the biggest obstacle in further improving the efficiency of the Pickering emulsion system. In this study, we propose and solve this problem for the first time using natural magnetotactic bacteria as nanoscale magnetic stirring bars, which can be encapsulated into each micro-droplet and used to stir the solution to accelerate the mass transportation under an external magnet, and thus significantly enhance the reaction rate of Pickering emulsion...
March 7, 2018: Chemical Science
Lauriane Alison, Ahmet Faik Demirörs, Elena Tervoort, Alexandra Teleki, Jan Vermant, André R Studart
In food-grade emulsions, particles with an appropriate surface modification can be used to replace surfactants and potentially enhance the stability of emulsions. During the life cycle of products based on such emulsions they can be exposed to a broad range of pH conditions and hence it is crucial to understand how pH changes affect stability of emulsions stabilized by particles. Here, we report on a comprehensive study of the stability, microstructure and macroscopic behaviour of pH-controlled oil-in-water emulsions containing silica nanoparticles modified with chitosan, a food-grade polycation...
May 2, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Gaihuan Ren, Maoxin Wang, Lei Wang, Zengzi Wang, Qianqian Chen, Zhenghe Xu, Dejun Sun
Dynamic covalent surfactants have been recently reported for preparation of pH switchable emulsions [Sun, D. Langmuir, 2017, 33, 3040]. In this study, dynamic covalent silica (SiO2-B) nanoparticles of switchable wettability were fabricated by a pH-responsive dynamic (covalent) imine bond between hydrophilic amino silica (SiO2-NH2) nanoparticles and hydrophobic benzaldehyde. The properties of SiO2-B were characterized by Fourier Transform Infrared (FTIR) Spectroscopy, Elemental Analysis, contact angle measurement and zeta potential measurement...
April 30, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Clara Jiménez-Saelices, Bastien Seantier, Yves Grohens, Isabelle Capron
Thermal superinsulating properties of biobased-materials are investigated via the structuration of aerogels through a biphasic system. Highly stable Pickering emulsions are produced using TEMPO-oxidized cellulose nanofibrils (NFC) adsorbed at an oil/water interface. NFCs form an entangled system of clusters of droplets that lead to excellent mechanical properties. The emulsions produced are strong gels that are further used as template to form aerogels. The freeze-dried emulsions result in porous bioaerogels with extremely low densities (0...
April 23, 2018: ACS Applied Materials & Interfaces
Jean-Paul Douliez, Nicolas Martin, Thomas Beneyton, Jean-Charles Eloi, J-Paul Chapel, Laurence Navailles, Jean-Christophe Baret, Stephen Mann, Laure Béven
We describe the fabrication of stable colloidosomes derived from water-in-water Pickering-like emulsions produced by addition of fluorescent amine-modified polystyrene latex beads to an aqueous two-phase system consisting of dextran-enriched droplets dispersed in a PEG-enriched continuous phase. Addition of polyacrylic acid followed by carbodiimide-induced crosslinking with dextran produces hydrogelled droplets capable of reversible swelling and selective molecular uptake and exclusion. Colloidosomes produced specifically in all-water systems could offer new opportunities in microencapsulation and the bottom-up construction of synthetic protocells...
April 23, 2018: Angewandte Chemie
Bernard P Binks, Samuel O Olusanya
Pickering emulsions stabilized by a mixture of colored organic pigment particles of different hydrophobicity have been investigated at equal oil/water ratio and a fixed overall particle concentration by several complementary methods. Transitional phase inversion of emulsions from water-in-oil to oil-in-water can be effected by increasing the fraction of hydrophilic pigment orange in mixtures with either hydrophobic pigment yellow, red, indigo, or blue. In two mixtures, we find that a distinct change in the color of emulsions occurs at phase inversion...
April 20, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Qinmo Luo, Peiran Wei, Qianwen Huang, Burcu Gurkan, Emily B Pentzer
Ion-accessible, large surface area, and complete wetting of a carbonaceous electrode by the electrolyte are crucial for high-performance electrochemical double layer capacitors. Herein, we report a facile and scalable method to prepare electrode-electrolyte hybrid materials where an ionic liquid (IL) electrolyte is encapsulated within a shell of reduced graphene oxide (GO) nanosheets as the active electrode material (called rGO-IL capsules). These structures were templated using Pickering-type emulsions consisting of a dispersed phase of 1-methyl-3-butylimidazolium hexafluorophosphate ([bmim][PF6]) and a continuous water phase; graphene oxide nanosheets were used as the surfactant, and interfacial polymerization yielded polyurea which bound the nanosheets together to form the capsule shell...
April 19, 2018: ACS Applied Materials & Interfaces
Li Jinfeng, Fayin Ye, Lin Lei, Yun Zhou, Guohua Zhao
The granules of sweet potato starch were size-fractionated into three portions with significantly different median diameters (D50) of 6.67 (small-sized), 11.54 (medium-sized) and 16.96 µm (large-sized), respectively. Each portion was hydrophobized at the mass-based degrees of substitution (DSm) of approximately 0.0095 (low), 0.0160 (medium) and 0.0230 (high). The Pickering emulsion stabilizing capacities of modified granules were tested, and the resultant emulsions were characterized. The joint effects of granule size and DSm on emulsifying capacity (EC) were investigated by response surface methodology...
April 17, 2018: Journal of Agricultural and Food Chemistry
Xin-Sheng Qin, Zhigang Luo, Xichun Peng
The natural quinoa protein isolate (QPI) was largely reflected in the nanoparticle form at pH 7.0 (about 401 nm), and the ultrasound at 20 min progressively improved the contact angle (wettability) and surface hydrophobicity of the nanoparticles. Ultrasound process also modified the type of intra-particle interaction, and the internal forces of sonicated particles were largely maintained by both disulfide bonds and hydrophobic interaction forces. In emulsion system, the ultrasound progressively increased the emulsification efficiency of the QPI nanoparticles, particularly at high protein concentration (c>1%, w/v), and higher emulsion stability against coalescence...
April 17, 2018: Journal of Agricultural and Food Chemistry
Shumaila Shahid, Swarup Rajesh, Madivala G Basavaraj
We present a simple and modular approach to realize highly stable pH responsive Pickering emulsion from mixtures of commercially available oppositely charged nanoparticle and polyelectrolyte. While highly charged nanoparticles and polyelectrolytes when used solely do not stabilize emulsions, we show that the electrostatic attraction between oppositely charged nanoparticles and polyelectrolytes can be exploited to formulate emulsions with long term stability of up to 8 months. The Ludox CL nanoparticles and poly (4-styrene sulfonate) sodium salt (PSS) when dispersed in aqueous solution at pH 2 to 11 form particle polyelectrolyte complexes (PPCs) due to hetero-aggregation...
April 12, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Katharina Hiebler, Georg J Lichtenegger, Manuel C Maier, Eun Sung Park, Renie Gonzales-Groom, Bernard P Binks, Heidrun Gruber-Woelfler
Within the "compartmentalised smart factory" approach of the ONE-FLOW project the implementation of different catalysts in "compartments" provided by Pickering emulsions and their application in continuous flow is targeted. We present here the development of heterogeneous Pd catalysts that are ready to be used in combination with biocatalysts for catalytic cascade synthesis of active pharmaceutical ingredients (APIs). In particular, we focus on the application of the catalytic systems for Suzuki-Miyaura cross-coupling reactions, which is the key step in the synthesis of the targeted APIs valsartan and sacubitril...
2018: Beilstein Journal of Organic Chemistry
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