Fluids with competing short-range attractions and long-range repulsions mimic dispersions of charge-stabilized colloids that can display equilibrium structures with intermediate-range order (IRO), including particle clusters. Using simulations and analytical theory, we demonstrate how to detect cluster formation in such systems from the static structure factor and elucidate links to macrophase separation in purely attractive reference fluids. We find that clusters emerge when the thermal correlation length encoded in the IRO peak of the structure factor exceeds the characteristic length scale of interparticle repulsions. We also identify qualitative differences between the dynamics of systems that form amorphous versus microcrystalline clusters.
We report here a facile synthetic approach for preparing water-soluble Fe3O4 nanoparticle (NP) clusters with tunable size distribution and magnetic properties. The primary NP sizes were controlled by tuning the nucleation and growth rates with temperature and ligand concentration while the nanocluster sizes were manipulated by controlling interparticle interactions. We have investigated the size control of clusters as well as individual primary NPs via dynamic light scattering (DLS) analysis and transmission electron microscopy (TEM). Superconducting quantum interference device (SQUID) was used to measure the magnetic properties of Fe3O4 NP for determining the effect of size distribution at room temperature. These water dispersible NP clusters can be utilized in various biomedical applications. In this study, we demonstrated the application of synthesized nanoclusters to enhance imaging contrast a novel ultrasound-based imaging modality, pulsed magneto-motive ultrasound (pMMUS) imaging. Our results indicated that by using the NP clusters with enhanced magnetic properties, the pMMUS signal increased significantly which is an essential requirement for further development of in vivo pMMUS imaging.Read More: http://www.worldscientific.com/doi/abs/10.1142/S1793292015500733
For foams with ultra low water contents, the capillary pressure is very large and induces rapid drainage that destabilizes the aqueous lamellae between the gas bubbles. However, we show that high-pressure CO2-in-water foams can be stabilized with a viscoelastic aqueous phase composed of entangled wormlike micelles, even for extremely high CO2 volume fractions ϕ of 0.95 to 0.98; the viscosity of these ultradry foams increased by up to 3–4-fold, reaching more than 100 cP relative to foams formed with conventional low viscosity aqueous phases. The foam morphology consisted of fine ∼20 μm polyhedral-shaped CO2 bubbles that were stable for hours. The wormlike micelles were formed by mixing anionic sodium lauryl ether sulfate (SLES) with salt and a protonated cationic surfactant, as shown by cryogenic transmission electron microscopy (cryo-TEM) and large values of the zero-shear viscosity and the dynamic storage and loss moduli. With the highly viscous continuous aqueous phases, the foam lamella drainage rates were low, as corroborated by confocal microscopy. The preservation of viscous thick lamellae resulted in lower rates of Ostwald ripening relative to conventional foams as shown by high-pressure optical microscopy. The ability to stabilize viscous ultra high internal phase foams is expected to find utility in various practical applications, including nearly “waterless” fracturing fluids for recovery of oil and gas in shale, offering the possibility of a massive reduction in the amount of wastewater
T. M. Truskett, Johnston, K. P., Maynard, J. A., Borwankar, A. U., Murthy, A. K., Stover, R. J., Wilson, B. K., Dinin, A. K., Laber, J. R., and Gourisankar, S., “Assembling nanoclusters in water for therapy or imaging,” ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY, vol. 247. AMER CHEMICAL SOC 1155 16TH ST, NW, WASHINGTON, DC 20036 USA, 2014.
Perovskite oxides have attracted significant attention as energy conversion materials for metal–air battery and solid-oxide fuel-cell electrodes owing to their unique physical and electronic properties. Amongst these unique properties is the structural stability of the cation array in perovskites that can accommodate mobile oxygen ions under electrical polarization. Despite oxygen ion mobility and vacancies having been shown to play an important role in catalysis, their role in charge storage has yet to be explored. Herein we investigate the mechanism of oxygen-vacancy-mediated redox pseudocapacitance for a nanostructured lanthanum-based perovskite, LaMnO3. This is the first example of anion-based intercalation pseudocapacitance as well as the first time oxygen intercalation has been exploited for fast energy storage. Whereas previous pseudocapacitor and rechargeable battery charge storage studies have focused on cation intercalation, the anion-based mechanism presented here offers a new paradigm for electrochemical energy storage
During deep-sea oil leaks, dispersants may be used to break up the oil into droplets smaller than about 70 μm, which may then be bioremediated by bacteria before they reach the ocean surface. To investigate the mechanism of droplet formation as a function of dispersant type, concentration, and jet velocity, a flowing oleophilic stream containing amphiphiles was mixed with flowing dodecane and then atomized through a 0.25 mm circular nozzle. The minimum droplet diameters were 2.2, 4.5, and 24 μm for only 5 w:v % amphiphile in the oil phase for Corexit 9500A, Tergitol 15-S-7 (C12H25CH(OCH2CH2)7OH), and a silica nanoparticle/Span 20 mixture, respectively. For Tergitol 15-S-7, the droplet size exhibited the expected scaling with Weber number (We) at low viscosity numbers (Vi < 50), where inertial forces overcome interfacial forces, and Reynolds number (Re) at high Vi numbers (Vi > 50), where inertial forces overcome viscous forces. However, in the case of the silica nanoparticle/Span 20 mixture, the magnitude of the exponent of We scaling was found to be smaller than −3/5. A better understanding of how low concentrations of dispersants (with relatively high oil–water interfacial tensions) may be used to provide a sufficient We with high inertial forces (high Re) in jets to form small oil droplets, which is of interest for advancing environmental protection in the undesired event of a deep-sea oil leak
Synergistic interactions between appropriately designed surface-modified nanoparticles and surfactants are shown to stabilize foams of CO2 bubbles/droplets dispersed in water at elevated temperature and pressure typical of subsurface formations for enhanced oil recovery or geologic storage of CO2. The foams are sufficiently viscous to mitigate or eliminate the instability associated with CO2 displacement of fluids resident in the oil reservoir or brine aquifer. This technology therefore has the potential to increase the efficiency of oil recovery and the efficiency of pore space utilization for storage.
Embodiments of the present disclosure include dispersion compositions having a nonionic surfactant for use in enhanced petroleum recovery, and methods of using the dispersion compositions in petroleum recovery processes. For the various embodiments, the nonionic surfactant of the dispersion composition promotes the formation of a dispersion from carbon dioxide and water
The transport of engineered nanoparticles in porous media is of interest in numerous applications including electromagnetic imaging of subsurface reservoirs, enhanced oil recovery, and CO2 sequestration. A series of poly(2-acrylamido-2-methyl-1-propanesulfonic acid-co-acrylic acid) (poly(AMPS-co-AA)) random copolymers were grafted onto iron oxide (IO) nanoparticles (NPs) to provide colloidal stability in American Petroleum Institute (API) standard brine (8 wt/wt % NaCl and 2 wt/wt %CaCl2, anhydrous basis). A combinatorial approach, which employed grafting poly(AMPS-co-AA) with wide ranges of compositions onto platform amine-functionalized IO NPs via a 1-ethyl-3-(3-(dimethylamino)propyl)carbondiimidecarbondiimide (EDC) catalyzed amidation, was used to screen a large number of polymeric coatings. The ratio of AMPS/AA was varied from 1:1 to 20:1 to balance the requirements of particle stabilization, low adsorption/retention (provided by 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS)), and permanent attachment of stabilizer (provided by acrylic acid (AA)). The resulting nanoparticles remained stable in aqueous suspension despite the extremely high salinity conditions and exhibited low adsorption on silica microspheres. Greater than 91% of applied IO-NP mass was transported through columns packed quartz sand, and the mobility of IO NP increased by ca. 6% when the AMPS to AA ratio was increased from 1:1 to 3:1, consistent with batch adsorption data. In both static batch reactor and dynamic column tests, the observed attachment of IO NPs was attributed to divalent cation (Ca2+) mediated bridging and hydrophobic interactions. Collectively, the rapid, high throughput combinatorial approach of grafting and screening (via batch adsorption) provides for the development of high mobility NPs for delivery in various porous media under high salinity conditions
Upon consideration of dispersant-related research, both before and after the Macondo Well oil release, it can be divided into two general categories: (1) the fundamentals of how dispersants work and the effects that may result from their use (e.g., physicochemical and transport characteristics of drops, bubbles, hydrates, surfactants), and (2) an applied focus that has emphasized the design of new dispersants or an enhancement of the performance of those products that are currently available.
While there is an extensive amount of data relating to dispersants, a main focus has been on the demonstration of their effectiveness in bench tests and examination of the toxicity of dispersants and dispersed oil. As a result, there is a need for an enhanced understanding of dispersant and dispersed oil thermodynamics and their fate and transport, with a goal to translate the science and engineering to the development of new, effective dispersant systems. The focus of the work to be discussed addresses the following areas:
Formation of small oil droplets: Widely dispersed stable oil droplets in the water column are easily accessible to microbes and therefore highly susceptible to degradation. It is important therefore, to understand the fundamental mechanisms of oil breakup and colloidal stabilization in order to develop new and effective dispersants.
Dispersant-related processes under deep sea conditions: Current dispersants have been developed for surface spills. The efficacy of such formulations when applied at the high pressures and low temperatures representative of deep ocean release has not been systematically studied. Because of concomitant gas release at the discharge point, and the pressures involved, the liquid droplet is essentially a gas-expanded liquid which could behave quite differently when treated with dispersant components depending upon how they partition at the phase interfaces, i.e., gas/water, gas/oil, oil/water.
Fluid mechanics of stabilized oil droplets: Droplet transport, as influenced by all thermodynamic variables of relevance under deep sea conditions, is being studied.
Droplet interactions with solid particulates: A better understanding of these processes, either in marine sediments or in the water column, will help predict the environmental fate of the droplets.
Development of alternative dispersants: Based on the knowledge gained with respect to the fundamentals, a key goal is the systematic translation of that understanding to the development of new and improved materials.
This paper summarizes recent work of a collaborative research effort involving investigators from 22 universities, with particular emphasis on increasing the understanding of the science and engineering of oil spill dispersants.
The mechanism by which polymers, when grafted to inorganic nanoparticles, lower the interfacial tension at the oil–water interface is not well understood, despite the great interest in particle stabilized emulsions and foams. A simple and highly versatile free radical “grafting through” technique was used to bond high organic fractions (by weight) of poly(oligo(ethylene oxide) monomethyl ether methacrylate) onto iron oxide clusters, without the need for catalysts. In the resulting ∼1 μm hybrid particles, the inorganic cores and grafting architecture contribute to the high local concentration of grafted polymer chains to the dodecane/water interface to produce low interfacial tensions of only 0.003 w/v % (polymer and particle core). This “critical particle concentration” (CPC) for these hybrid inorganic/polymer amphiphilic particles to lower the interfacial tension by 36 mN/m was over 30-fold lower than the critical micelle concentration of the free polymer (without inorganic cores) to produce nearly the same interfacial tension. The low CPC is favored by the high adsorption energy (∼106 kBT) for the large ∼1 μm hybrid particles, the high local polymer concentration on the particles surfaces, and the ability of the deformable hybrid nanocluster cores as well as the polymer chains to conform to the interface. The nanocluster cores also increased the entanglement of the polymer chains in bulk DI water or synthetic seawater, producing a viscosity up to 35 000 cP at 0.01 s–1, in contrast with only 600 cP for the free polymer. As a consequence of these interfacial and rheological properties, the hybrid particles stabilized oil-in-water emulsions at concentrations as low as 0.01 w/v %, with average drop sizes down to 30 μm. In contrast, the bulk viscosity was low for the free polymer, and it did not stabilize the emulsions. The ability to influence the interfacial activity and rheology of polymers upon grafting them to inorganic particles, including clusters, may be expected to be broadly applicable to stabilization of emulsions and foams
Nanoparticles (diameter of approximately 5 to 50 nm) easily pass through typical pore throats in reservoirs, but physicochemical attraction between nanoparticles and pore walls may still lead to significant retention. We conducted an extensive series of nanoparticle-transport experiments in core plugs and in columns packed with crushed sedimentary rock, systematically varying flow rate, type of nanoparticle, injection-dispersion concentration, and porous-medium properties. Effluent-nanoparticle-concentration histories were measured with fine resolution in time, enabling the evaluation of nanoparticle adsorption in the columns during slug injection and post-flushes. We also applied this analysis to nanoparticle-transport experiments reported in the literature.
Our analysis suggests that nanoparticles undergo both reversible and irreversible adsorption. Effluent-nanoparticle concentration reaches the injection concentration during slug injection, indicating the existence of an adsorption capacity. Experiments with a variety of nanoparticles and porous media yield a wide range of adsorption capacities (from 10–5 to 101 mg/g for nanoparticles and rock, respectively) and also a wide range of proportions of reversible and irreversible adsorption. Reversible- and irreversible-adsorption sites are distinct and interact with nanoparticles independently. The adsorption capacities are typically much smaller than monolayer coverage. Their values depend not only on the type of nanoparticle and porous media, but also on the operating conditions, such as injection concentration and flow rate
A facile “grafting through” approach was developed to tether tunable quantities of poly(2-acrylamido-2-methylpropanesulfonic acid) (PAMPS) as well as zwitterionic poly([3-(methacryloylamino)propyl]dimethyl(3-sulfopropyl)ammonium hydroxide) (PMPDSA) homopolymer onto iron oxide (IO) nanoparticles (NPs). In this case, homopolymers may be grafted, unlike “grafting to” approaches that often require copolymers containing anchor groups. The polymer coating provided steric stabilization of the NP dispersions at high salinities and elevated temperature (90 °C) and almost completely prevented adsorption of the NPs on silica microparticles and crushed Berea sandstone. The adsorption of PAMPS IO NPs decreased with the polymer loading, whereby the magnitude of the particle-surface electrosteric repulsion increased. The zwitterionic PMPDSA IO NPs displayed 1 order of magnitude less adsorption onto crushed Berea sandstone relative to the anionic PAMPS IO NPs. The ability to design homopolymer coatings on nanoparticle surfaces by the “grafting through” technique is of broad interest for designing stable dispersions and modulating the interactions between nanoparticles and solid surfaces
The present invention also provides a high concentration low viscosity suspension of an pharmaceutically acceptable solvent with one or more sub-micron or micron-sized non-crystalline particles comprising one or more proteins or peptides. Optionally one or more additives in the pharmaceutically acceptable solvent to form a high concentration low viscosity suspension with a concentration of at least 20 mg/ml and a solution viscosity of between 2 and 100 centipoise that is suspendable upon shaking or agitation, wherein upon delivery the one or more sub-micron or micron-sized peptides dissolves and do not form peptide aggregates syringeable through a 21 to 27-gauge needle.