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Pickering emulsion

Tobias Bollhorst, Kurosch Rezwan, Michael Maas
Utilizing colloidal particles for the assembly of the shell of nano- and microcapsules holds great promise for the tailor-made design of new functional materials. Increasing research efforts are devoted to the synthesis of such colloidal capsules, by which the integration of modular building blocks with distinct physical, chemical, or morphological characteristics in a capsule's shell can result in novel properties, not present in previous encapsulation structures. This review will provide a comprehensive overview of the synthesis strategies and the progress made so far of bringing nano- and microcapsules with shells of densely packed colloidal particles closer to application in fields such as chemical engineering, materials science, or pharmaceutical and life science...
February 23, 2017: Chemical Society Reviews
Ying Cong, Qiuju Li, Min Chen, Limin Wu
Stimuli-responsive microcontainers have become a major topic of interest, from fundamental aspects to applications in materials science. However, microcontainers that enable the loading of multiple species and programmable release are mostly unexplored. Herein, we describe the design and synthesis of a dual-responsive organic/inorganic hybrid microcontainer with two payloads in separate storage spaces that is formed by the rapid UV-initiated polymerization of Pickering emulsions. The stellate mesopore silica nanoparticles with poly(N-isopropylacrylamide) grafted inside the mesopores were loaded with one compound (Nile red) and used as Pickering emulsifiers to stabilize oil-in-water droplets...
February 21, 2017: Angewandte Chemie
Miguel Angel Fernandez-Rodriguez, Bernard P Binks, Miguel Angel Rodriguez-Valverde, Miguel Angel Cabrerizo-Vilchez, Roque Hidalgo-Alvarez
Particles adsorbed at liquid interfaces are commonly used to stabilise water-oil Pickering emulsions and water-air foams. The fundamental understanding of the physics of particles adsorbed at water-air and water-oil interfaces is improving significantly due to novel techniques that enable the measurement of the contact angle of individual particles at a given interface. The case of non-aqueous interfaces and emulsions is less studied in the literature. Non-aqueous liquid-liquid interfaces in which water is replaced by other polar solvents have properties similar to those of water-oil interfaces...
February 7, 2017: Advances in Colloid and Interface Science
Fen Xue, Yabin Zhang, Fengwei Zhang, Xiaomin Ren, Hengquan Yang
Interface-active particle materials that are able to assemble at the oil/water interface so as to stabilize droplets, are gaining unprecedented interest due to the intriguing applications in catalysis and materials synthesis, etc. In contrast to these potential applications, this kind of materials are still limited and cannot meet some particular demands of practical utilizations such as rationally designed interfacial activity and high stability against concentrated salts. In this contribution, interface-active mesoporous silica nanospheres (MSS@CxZy) are synthesized through simultaneous incorporation of extremely hydrophilic zwitterionic moiety and hydrophobic octyl moiety in the shell...
February 21, 2017: ACS Applied Materials & Interfaces
Frank Bossler, Lydia Weyrauch, Robert Schmidt, Erin Koos
The rheological properties of a suspension can be dramatically altered by adding a small amount of a secondary fluid that is immiscible with the bulk liquid. These capillary suspensions exist either in the pendular state where the secondary fluid preferentially wets the particles or the capillary state where the bulk fluid is preferentially wetting. The yield stress, as well as storage and loss moduli, depends on the size and distribution of secondary phase droplets created during sample preparation. Enhanced droplet breakup leads to stronger sample structures...
April 5, 2017: Colloids and Surfaces. A, Physicochemical and Engineering Aspects
Kaihong Liu, Jianzhong Jiang, Zhenggang Cui, Bernard P Binks
pH-responsive oil-in-water Pickering emulsions were prepared simply by using negatively charged silica nanoparticles in combination with a trace amount of a zwitterionic carboxyl betaine surfactant as stabilizer. Emulsions are stable to coalescence at pH  5 but phase separate completely at pH > 8.5. In acidic solution, the carboxyl betaine molecules become cationic allowing them to adsorb on silica nanoparticles via electrostatic interactions, thus hydrophobizing and flocculating them enhancing their surface activity...
February 13, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
N P Aditya, Ian E Hamilton, Ian T Norton
Particle characteristics e.g. size and polymorphism are known to significantly affect the Pickering ability of the solid particles by influencing their interaction at the oil and water (O/W) interface. In this study, nano-sized amorphous curcumin particles were fabricated using nanonization technology to use them as Pickering particles. After nanonization, native crystalline curcumin particles were converted into amorphous, nanosized particles of ∼220nm. Amorphous nature of the particle was evident from the decreased melting point from 177±1°C (native curcumin) to 146±3°C (nanonized curcumin) and enthalpy from 27±2J/g to 3...
June 1, 2017: Food Chemistry
KyuHan Kim, Subeen Kim, Jiheun Ryu, Jiyoon Jeon, Se Gyu Jang, Hyunjun Kim, Dae-Gab Gweon, Won Bin Im, Yosep Han, Hyunjung Kim, Siyoung Q Choi
High internal phase emulsions have been widely used as templates for various porous materials, but special strategies are required to form, in particular, particle-covered ones that have been more difficult to obtain. Here, we report a versatile strategy to produce a stable high internal phase Pickering emulsion by exploiting a depletion interaction between an emulsion droplet and a particle using water-soluble polymers as a depletant. This attractive interaction facilitating the adsorption of particles onto the droplet interface and simultaneously suppressing desorption once adsorbed...
February 1, 2017: Nature Communications
Weiping Jin, Jieyu Zhu, Yike Jiang, Ping Shao, Bin Li, Qingrong Huang
Particle size and surface wettability play leading roles in the distribution of particles on the oil-water interface and the stability of emulsions. This work utilized nanocomplexes assembled from gelatin and tannic acid to stabilize Pickering emulsions. The sizes and surface wettability of particles were further regulated by using a polysaccharide. The sizes of nanocomplexes ranged from 205.8 to 422.2 nm and increased with the addition of polysaccharide. Their contact angles decreased from 84.1° to 59.3°, revealing their hydrophilic nature...
February 10, 2017: Journal of Agricultural and Food Chemistry
Li Ruiyi, Li Zaijun, Liu Junkang
Carbon-based dots (CDs) are nanoparticles with size-dependent optical and electronic properties that have been widely applied in energy-efficient displays and lighting, photovoltaic devices and biological markers. However, conventional CDs are difficult to be used as ideal stabilizer for Pickering emulsion due to its irrational amphiphilic structure. The study designed and synthesized a new histidine-functionalized carbon dot-Zinc(II) nanoparticles, which is termed as His-CD-Zn. The His-CD was made via one-step hydrothermal treatment of histidine and maleic acid...
January 5, 2017: Journal of Colloid and Interface Science
Yuchen Zhou, Junjie Huang, Wei Sun, Yuanlai Ju, Pinghui Yang, Lingyun Ding, Zhong-Ren Chen, Julia A Kornfield
Patterned porous surfaces with responsive functionalities are fabricated by a thermoresponsive microgel-assisted breath figure (BF) process. When water droplets submerge into a polystyrene (PS) solution during formation of a porous surface by the bottom-up BF process, poly(N-isopropylacrylamide)-co-acrylic acid (PNIPAm-co-AA) microgels dispersed in the solution spontaneously assemble at the water-organic interfaces like "Pickering emulsions", reinforced by capillary flow. The conformal layer of PNIPAm-co-AA microgels lining the pores appears in images from a scanning electron microscope (SEM) either as a smooth surface layer (L) or as an array of domelike protrusions (D), depending on the conditions at which the sample was dried for SEM...
February 1, 2017: ACS Applied Materials & Interfaces
Tomohiro G Noguchi, Yasutaka Iwashita, Yasuyuki Kimura
Amphiphilic Janus particles (AJP), composed of hydrophilic and hydrophobic hemispheres, are one of the simplest anisotropic colloids, and they exhibit higher surface activities than particles with homogeneous surface properties. Consequently, a ternary system of AJP, water, and oil can form extremely stable Pickering emulsions, with internal structures that depend on the Janus structure of the particles and the system composition. However, the detail of these structures has not been fully explored, especially for the composition range where the amount of the minority liquid phase and AJP are comparable, where one would expect the Janus characteristics to be directly reflected...
January 19, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Huan Tan, Lifeng Zhao, Sisi Tian, Hui Wen, Xiaojun Gou, To Ngai
The potential application of Pickering high-internal phase emulsions (HIPEs) in the food and pharmaceutical industries has yet to be fully developed. Herein, we synthesized fairly monodisperse, nontoxic, autofluorescent gelatin particles for use as sole stabilizers for fabricating oil-in-water (O/W) HIPEs in an effort to improve the protection and bioaccessibility of entrapped β-carotene. Our results showed that the concentration of gelatin particles determined the formation, microstructure, droplet size distribution, and digestion profile of the HIPEs...
February 1, 2017: Journal of Agricultural and Food Chemistry
Susanne Sihler, Ulrich Ziener
Water-soluble organic dyes such as fluorescein are widely used, mainly for coloration of, e.g., biological samples and groundwater tracing, and they are not obviously amphiphilic by molecular structure like surfactants. Here, we show that the dyes alone stabilize oil-in-water emulsions. Exemplarily, fluorescein is compared with the classical surfactant sodium dodecyl sulfate (SDS) by means of surface/interfacial tension, concentration of stabilizer and electrolyte, as well as pH. The principle can be extended to further classes of water-soluble dyes, which keep up with or exceed SDS by efficiency...
January 23, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Xuezhen Wang, Minxiang Zeng, Yi-Hsien Yu, Huiliang Wang, M Sam Mannan, Zhengdong Cheng
Asymmetric Janus and Gemini ZrP-PNIPAM monolayer nanoplates were obtained by exfoliation of two-dimensional layered ZrP disks whose surface was covalently modified with thermosensitive polymer PNIPAM. The nanoplates largely reduced interfacial tension (IFT) of the oil/water interface so that they were able to produce stable oil/water emulsions, and the PNIPAM grafting either on the surface or the edge endowed the nanoplates rapid temperature responsivity. The ZrP-PNIPAM nanoplates proved to be thermosensitive Pickering emulsifiers for controlled-release applications...
February 13, 2017: ACS Applied Materials & Interfaces
Ji Hoon Park, Nuri Han, Ji Eun Song, Eun Chul Cho
A surfactant-free approach is proposed to synthesize nonspherical Janus particles with temperature-dependent wettability on hydrophobic surfaces. Sub-micrometer-sized particles comprising poly(styrene-co-divinylbenzene) core and a thermally responsive poly(N-isopropylacrylamide-co-methacrylic acid) shell are first synthesized to stabilize styrene droplets in water, producing a Pickering emulsion. Upon heating to 80 °C and subsequent addition of initiators to the aqueous phase, styrene droplets are polymerized and combine with the core-shell particles to construct dumbbell-shaped nonspherical particles...
December 22, 2016: Macromolecular Rapid Communications
Taeseung Yang, Sang Koo Choi, Daehwan Park, Yea Ram Lee, Chan Bok Chung, Jin Woong Kim
This study introduces a new type of associative nanoparticle (ANP) that provides controlled chain-to-chain attraction with an associative polymer rheology modifier (APRM) to produce highly stable Pickering emulsions. The ANPs were synthesized by grafting hydrophobically modified hygroscopic zwitterionic poly(2-methacryloyloxyethyl phosphorylcholine-co-stearyl methacrylate) brushes onto 20 nm sized silica NPs via surface-mediated living radical polymerization. The ANP-stabilized Pickering emulsions show significant viscosity enhancement in the presence of the APRM...
December 20, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
A Tamayo Tenorio, E W M de Jong, C V Nikiforidis, R M Boom, A J van der Goot
Thylakoids membranes are sophisticated, dynamic structures found in plant leaves, composed of protein complexes in a dynamic lipid matrix. The interfacial absorption dynamics and viscoelasticity of thylakoid membranes fragments were measured to assess the properties of the interfacial layer and to elucidate an emulsifying mechanism that includes the role of thylakoid's composition and 3D structure. Thylakoid membranes were extracted from sugar beet leaves by a series of buffer washing, filtration and centrifugation...
January 18, 2017: Soft Matter
Xin Wang, Kai Liang, Yaling Tian, Yali Ji
Chitin nanocrystal (ChiNC) is a promising reinforcing nanofiller for biomedical polymers. However, its self-aggregation characteristics caused processing difficulty in developing ChiNC-based nanocomposites. Herein, a new degradable crosslinked bioelastomer, designated as poly(1,8-octanediol-co-Pluronic F127 citrate) (POFC) was synthesized by melt polycondensation of citric acid, 1,8-octanediol, and Pluronic F127. In comparison to poly(1,8-octanediol citrate) (POC), POFC pre-polymer exhibited self-emulsifying property...
February 10, 2017: Carbohydrate Polymers
Hisfazilah Saari, Catalina Fuentes, Malin Sjöö, Marilyn Rayner, Marie Wahlgren
The aim of this study was to investigate non-solvent precipitation of starch to produce nanoparticles that could be used in Pickering emulsions. The material used was waxy maize, modified with octenyl succinic anhydride. Different methods of non-solvent precipitation were investigated, and a method based on direct mixing of an 8% starch solution and ethanol (ratio 1:1) was found to produce the smallest particles. The particle size was measured using AFM and AF4, and was found to be in the range 100-200nm. However, both larger particles and aggregates of nanoparticles were observed...
February 10, 2017: Carbohydrate Polymers
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