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Pickering emulsion

Huazhang Guo, Duanguang Yang, Mei Yang, Yong Gao, Yijiang Liu, Huaming Li
In this study, pH- and glucose-responsive Pickering emulsions stabilized by core crosslinked polymer nanoparticles, which were constructed via reversible covalent bonds, were presented for the first time. Firstly, well-defined PDMA-b-PAPBA (poly(N,N-dimethylacrylamide)-b-poly(3-acrylamidophenylboronic acid)) diblock copolymers were synthesized via sequential reversible addition-fragmentation chain transfer (RAFT) polymerization reactions. By means of complexation of PBA units of PDMA-b-PAPBA with PVA in basic water, core crosslinked polymer nanoparticles (CCPNs) with a core-shell structure were formed...
November 18, 2016: Soft Matter
Jeniree A Flores, Ashlee A Jahnke, Adriana Pavia-Sanders, Zhengdong Cheng, Karen L Wooley
Magnetically-active hybrid networks (MHNs) are complex inorganic/organic composite materials that have been synthesized from the coupling of amine-functionalized iron oxide nanoparticles (amine-IONs) and pre-assembled shell crosslinked knedel-like (SCK) polymeric nanoconstructs. The intricate structure of these materials is composed of several inter-connected bundles of SCKs covalently bound to amine-IONs, which afford them magnetic responsivity. The MHNs were originally designed to sequester complex hydrocarbons from water; however, they have displayed a remarkable ability to form stable Pickering emulsions between organic solvents and water, upon mechanical stimulus...
November 3, 2016: Soft Matter
C J Mable, K L Thompson, M J Derry, O O Mykhaylyk, B P Binks, S P Armes
Polymerization-induced self-assembly (PISA) is used to prepare linear poly(glycerol monomethacrylate)-poly(2-hydroxypropyl methacrylate)-poly(benzyl methacrylate) [PGMA-PHPMA-PBzMA] triblock copolymer nano-objects in the form of a concentrated aqueous dispersion via a three-step synthesis based on reversible addition-fragmentation chain transfer (RAFT) polymerization. First, GMA is polymerized via RAFT solution polymerization in ethanol, then HPMA is polymerized via RAFT aqueous solution polymerization, and finally BzMA is polymerized via "seeded" RAFT aqueous emulsion polymerization...
October 25, 2016: Macromolecules
Tanapon Phenrat, Itsaraphong Kumloet
In this study, a novel electromagnetically enhanced treatment concept is proposed for in situ remediation of a source zone of chlorinated dense non-aqueous phase liquid (DNAPL) that is slowly dissolved, causing contaminated groundwater for centuries. Here, we used polystyrene sulfonate (PSS)-modified nanoscale zerovalent iron (NZVI) particles (ferromagnetic) in combination with a low frequency (LF) (150 kHz) AC electromagnetic field (EMF) to accelerate the degradation of the DNAPLs via enhanced dissolution and reductive dechlorination...
December 15, 2016: Water Research
Yongmin Zhang, Shuang Guo, Wentao Wu, Zhirong Qin, Xuefeng Liu
Herein, we describe a strategy of fabricating CO2-triggered oil-in-water Pickering emulsion based on silica nanoparticles func-tionalized in situ by a trace amount of conventional CO2-switchable surfactant, N-(3-(dimethylamino)propyl)alkyl amide (CnPMA). By alternately bubbling CO2 and N2 at a moderate conditions (30 oC, 80 mL·min-1), silica nanoparticles reversibly switch between amphipathic and hydrophilic as a result of the adsorption of ammonium (CO2) and the desorption of ter-tiary amine (N2). The emulsion can then be smart switched "on (stable)" and "off (unstable)," along with homogenization, without needing cooling and heating...
October 26, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
Tim Granath, Angela Sanchez-Sanchez, Aleksey Shmeliov, Valeria Nicolosi, Vanessa Fierro, Alain Celzard, Karl Mandel
Herein, the formation of hollow microballoons derived from superparamagnetic iron oxide nanoparticles with silica patches is reported. Depending on the experimental conditions, single- or multi-shelled superparamagnetic microballoons as well as multivesicular structures were obtained. We show how such structural changes follow a life-like process which is based on self-directing Pickering emulsions. We further demonstrate that the key towards the formation of such complex architectures is the patchy nature of the nanoparticles...
October 26, 2016: ACS Nano
Sanna Björkegren, Lars Nordstierna, Anders Törncrona, Anders Palmqvist
Colloidal silica particles, functionalized with hydrophilic and hydrophobic groups, have been studied for utilization in particle-stabilized emulsions, so called Pickering emulsions. The amounts of attached groups have been characterized using NMR spectroscopy and elemental analysis. A range of particles were prepared, with sizes from around 13 to 70nm in diameter. Hydrophilic functionalization of the silica sols was achieved by attaching methyl poly(ethylene glycol) (mPEG) silane to the silica particle surface...
October 15, 2016: Journal of Colloid and Interface Science
Ming Zhang, Ai-Juan Wang, Jun-Ming Li, Na Song, Yang Song, Rui He
Hydroxyapatite (HAp) nanoparticle stabilized Pickering emulsion was fabricated with poly(l-lactic acid) dissolved in dichloromethane (CH2Cl2) solution as oil phase and HAp aqueous dispersion as aqueous phase. Pickering emulsion was cured via in situ solvent evaporation method. Effect of PLLA concentrations, pH value, HAp concentrations, oil-water ratio, emulsification rates and times were studied on emulsion stability and emulsion type, etc. The results indicated emulsion stability increased with the increase of HAp concentration, emulsification rate and time; it is very stable when pH value of aqueous phase was adjusted to 10...
January 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
Oumar Bashir, Jerome P Claverie, Pierre Lemoyne, Charles Vincent
Bacillus thuringiensis (B. t.) based formulations have been widely used to control lepidopteran pests in agriculture and forestry. One of their weaknesses is their short residual activity when sprayed in the field. Using Pickering emulsions, mixtures of spores and crystals from three B. t. serovars were successfully encapsulated in colloïdosomal microparticles (50 μm) using innocuous chemicals (acrylic particles, sunflower oil, iron oxide nanoparticles, ethanol and water). A pH trigger mechanism was incorporated within the particles so that B...
2016: PeerJ
Xiantao Shen, Chuixiu Huang, Sudhirkumar Shinde, Kishore Kumar Jagadeesan, Simon Ekström, Emelie Fritz, Börje Sellergren
This work describes the preparation and investigation of molecularly imprinted polymer (MIP) microgels (MGs) stabilized Pickering emulsions (PE) for their ability to catalyze the formation of disulfide bonds in peptides at the O/W interface. The MIP MGs were synthesized via precipitation polymerization and a programmed initiator change strategy. The MIP MGs were characterized using DLS analysis, SEM measurement and optical microscopy analysis. The dry and wet MIP MGs showed a hydrodynamic diameter of 100 nm and 280 nm, respectively...
October 17, 2016: ACS Applied Materials & Interfaces
Liao Peng, Anchao Feng, Senyang Liu, Meng Huo, Tommy Fang, Ke Wang, Yen Wei, Xiaosong Wang, Jinying Yuan
Potential-stimulated Pickering emulsions, using electrochemical responsive microgels as particle stabilizers, are prepared and used for biocatalysis. The microgels are constructed from the cyclodextrin functionalized 8-arm poly(ethylene glycol) (8A PEG-CD) and ferrocene modified counterparts (8A PEG-Fc) via a CD-Fc host-guest chemistry. Taking advantage of the redox reaction of Fc, the formation and deformation of the microgels and corresponding Pickering emulsions can be reversibly stimulated by external potential, and have been used for the hydrolysis of triacetin and kinetic resolution reaction of (R,S)-1-phenylethanol catalyzed by lipases...
October 14, 2016: ACS Applied Materials & Interfaces
Anna Wang, Ryan McGorty, David M Kaz, Vinothan N Manoharan
Previous experiments have shown that spherical colloidal particles relax to equilibrium slowly after they adsorb to a liquid-liquid interface, despite the large interfacial energy gradient driving the adsorption. The slow relaxation has been explained in terms of transient pinning and depinning of the contact line on the surface of the particles. However, the nature of the pinning sites has not been investigated in detail. We use digital holographic microscopy to track a variety of colloidal spheres-inorganic and organic, charge-stabilized and sterically stabilized, aqueous and non-aqueous-as they breach liquid interfaces...
October 13, 2016: Soft Matter
K S Mikkonen, D Merger, P Kilpeläinen, L Murtomäki, U S Schmidt, M Wilhelm
Materials manufacturing industries seek efficient, economic, and sustainable compounds for stabilizing dispersed systems such as emulsions. In this study, novel, abundant biobased hydrocolloids spruce galactoglucomannans (GGM) and birch glucuronoxylans (GX) were obtained from a forestry biorefining process and characterized as versatile stabilizers of rapeseed oil-in-water emulsions. For the first time, GGM and GX isolated by pressurized hot water extraction (PHWE) of spruce and birch saw meal, respectively, were studied in emulsions...
September 27, 2016: Soft Matter
Hamza Al-Shehri, Tommy S Horozov, Vesselin N Paunov
We prepared model porous composite supra-particles and investigated the effect of the initial infused fluid phase on their attachment at the liquid-fluid interface. We used a simple method for fabrication of millimetre-sized spherical porous supra-particles from much smaller monodisperse latex microparticles as building blocks by evaporation of a polystyrene sulphate latex suspension on a hot super-hydrophobic surface. We annealed the dried supra-particles at the polymer's glass transition temperature to fuse partially their latex particle building blocks...
October 12, 2016: Soft Matter
Ye Zhu, Jianhua Sun, Chenglin Yi, Wei Wei, Xiaoya Liu
In this study, a one-step generation of stable multiple Pickering emulsions using pH-responsive polymeric nanoparticles as the only emulsifier was reported. The polymeric nanoparticles were self-assembled from an amphiphilic random copolymer poly(dodecyl acrylate-co-acrylic acid) (PDAA), and the effect of the copolymer content on the size and morphology of PDAA nanoparticles was determined by dynamic light scattering (DLS) and transmission electron microscopy (TEM). The emulsification study of PDAA nanoparticles revealed that multiple Pickering emulsions could be generated through a one-step phase inversion process by using PDAA nanoparticles as the stabilizer...
September 13, 2016: Soft Matter
Vesselin N Paunov, Hamza Al-Shehri, Tommy S Horozov
We developed and tested a theoretical model for the attachment of fluid-infused porous supra-particles to a fluid-liquid interface. We considered the wetting behaviour of agglomerated clusters of particles, typical of powdered materials dispersed in a liquid, as well as of the adsorption of liquid-infused colloidosomes at the liquid-fluid interface. The free energy of attachment of a composite spherical porous supra-particle made from much smaller aggregated spherical particles to the oil-water interface was calculated...
September 29, 2016: Physical Chemistry Chemical Physics: PCCP
Liang Ee Low, Beng Ti Tey, Boon Hoong Ong, Eng Seng Chan, Siah Ying Tang
We studied the formation of palm olein-in-water (O/W) Pickering emulsion stabilized by Fe3O4-cellulose nanocrystals (MCNC) nanocomposites obtained by ultrasound assisted in-situ co-precipitation method. The synthesized MCNC nanocomposites successfully stabilized Pickering emulsion with dual responses. The magnetic tests revealed a direct-relation between attractability of MCNC-stabilized Pickering emulsions and the emulsion droplet diameter. The Pickering emulsions were stable under pH ranging from 3 to 6. The stability substantially reduced around pH 8-10, and regained slowly when approaching pH 13...
January 2, 2017: Carbohydrate Polymers
Huirong Yang, Hongxia Zhang, Junxia Peng, Yuanyuan Zhang, Guanqun Du, Yu Fang
This study presents the general method to formulate magnetically responsive ionic liquid (IL)-based Pickering emulsions that are stabilized by amphiphilic Fe3O4 nanoparticles. The magnetic nanoparticle stabilizer (MN-CHOL) was synthesized using the surface-initiated ATRP method with further modification that uses a specially designed cholesteryl derivative, and characterized by FT-IR, XPS, TGA, and magnetization measurements. It is confirmed that the resulting MN-CHOL shows a stronger interfacial activity, efficiently emulsifying C4mim [PF6] and water, and resultantly forming stable Pickering emulsions without the help of any co-surfactant...
January 1, 2017: Journal of Colloid and Interface Science
Sebastian Glonke, Gabriele Sadowski, Christoph Brandenbusch
Biphasic whole-cell biotransformations are known to be efficient alternatives to common chemical synthesis routes, especially for the production of, e.g. apolar enantiopure organic compounds. They provide high stereoselectivity combined with high product concentrations owing to the presence of an organic phase serving as substrate reservoir and product sink. Industrial implementation suffers from the formation of stable Pickering emulsions caused by the presence of cells. State-of-the-art downstream processing includes inefficient strategies such as excessive centrifugation, use of de-emulsifiers or thermal stress...
November 2016: Journal of Industrial Microbiology & Biotechnology
Like Mao, Di Wang, Fuguo Liu, Yanxiang Gao
β-Carotene has been widely investigated both in the industry and academia, due to its unique bioactive attributes as an antioxidant and pro-vitamin A. Many attempts were made to design delivery systems for β-carotene to improve its dispersant state and chemical stability, and finally to enhance the functionality. Different types of oil-in-water emulsions were proved to be effective delivery systems for lipophilic bioactive ingredients, and intensive studies were performed on β-carotene emulsions in the last decade...
September 19, 2016: Critical Reviews in Food Science and Nutrition
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