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.
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
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.
Environmentally benign clay particles are of great interest for the stabilization of Pickering emulsions. Dodecane-in-synthetic seawater (SSW) emulsions formed with montmorillonite (MMT) clay microparticles modified with bis(2-hydroxyethyl)oleylamine were stable against coalescence, even at clay concentrations down to 0.1% w/v. Remarkably, as little as 0.001% w/v surfactant lowered the hydrophilicity of the clay to a sufficient level for stabilization of oil-in-SSW emulsions. The favorable effect of SSW on droplet size reduction and emulsion stability enhancement is hypothesized to be due to reduced electrostatic repulsion between adsorbed clay particles and a consequent increase in the continuous phase (an aqueous clay suspension) viscosity. Water/oil (W/O) emulsions were inverted to O/W either by decreasing the mass ratio of surfactant-to-clay (transitional inversion) or by increasing the water volume fraction (catastrophic inversion). For both types of emulsions, coalescence was minimal and the sedimentation or creaming was highly correlated with the droplet size. For catastrophic inversions, the droplet size of the emulsions was smaller in the case of the preferred curvature. Suspensions of concentrated clay in oil dispersions in the presence of surfactant were stable against settling. The mass transfer pathways during emulsification of oil containing the clay particles were analyzed on the droplet size/stability phase diagrams to provide insight for the design of dispersant systems for remediating surface and subsurface oceanic oil spills
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
Gold nanospheres coated with a binary monolayer of bound citrate and cysteine ligands were assembled into nanoclusters, in which the size and near-infrared (NIR) extinction were tuned by varying the pH and concentration of added NaCl. During full evaporation of an aqueous dispersion of 4.5 ± 1.8 nm Au primary particles, the nanoclusters were formed and quenched by the triblock copolymer polylactic acid (PLA)(1K)-b-poly(ethylene glycol) (PEG)(10K)-b-PLA(1K), which also provided steric stabilization. The short-ranged depletion and van der Waals attractive forces were balanced against longer ranged electrostatic repulsion to tune the nanocluster diameter and NIR extinction. Upon lowering the pH from 7 to 5 at a given salinity, the magnitude of the charge on the primary particles decreased, such that the weaker electrostatic repulsion increased the hydrodynamic diameter and, consequently, NIR extinction of the clusters. At a given pH, as the concentration of NaCl was increased, the NIR extinction decreased monotonically. Furthermore, the greater screening of the charges on the nanoclusters weakened the interactions with PLA(1K)-b-PEG(10K)-b-PLA(1K) and thus lowered the amount of adsorbed polymer on the nanocluster surface. The generalization of the concept of self-assembly of small NIR-active nanoclusters to include a strongly bound thiol and the manipulation of the morphologies and NIR extinction by variation of pH and salinity not only is of fundamental interest but also is important for optical biomedical imaging and therapy
The present invent ion 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
We present a series of perovskite electrocatalysts that are highly active for both the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) in an aqueous alkaline electrolyte. Lanthanum-based perovskites containing different transition metal active sites (LaBO3, B = Ni, Ni0.75Fe0.25, Co, Mn) are synthesized by a general colloidal method, yielding phase pure catalysts of homogeneous morphology and surface area (8–14 m2/g). Each perovskite’s ability to catalyze the OER and ORR is examined using thin film rotating disk electrochemistry (RDE). LaCoO3 supported on nitrogen-doped carbon is shown to be ∼3 times more active for the OER than high-surface-area IrO2. Furthermore, LaCoO3 is demonstrated to be highly bifunctional by having a lower total overpotential between the OER and ORR (ΔE = 1.00 V) than Pt (ΔE = 1.16) and Ru (ΔE = 1.01). The OER and ORR pathways are perturbed by the introduction of peroxide disproportionation functionality via support interactions and selective doping of the catalyst. LaNi0.75Fe0.25O3’s ability to disproportionate peroxide is hypothesized to be responsible for the ∼50% improvement over LaNiO3 in catalytic activity toward the ORR, despite similar electronic structure. These results allow us to examine the pathways for OER and ORR in context of support interactions, transition metal redox processes, and catalytic bifunctionality.
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.
We evaluate the transport of surface-treated superparamagnetic iron-oxide nanoparticles in Boise-sandstone rocks by injecting aqueous dispersions of the particles into core plugs. Several different surface treatments yield stable dispersions of these particles, but provide very different transport characteristics. Effluent concentration histories are measured to obtain the particle retention in the rock. The results are used to optimize the particle surface coating so that the reservoir application requirements for the functional nanoparticles can be achieved. The application of interest here requires the nanoparticles to adsorb to oil/water interfaces.
Our earlier experiments (Yu et al., 2010) showed that the paramagnetic nanoparticles stabilized with small negatively-charged citrate ligands have little retention in sedimentary rocks, but their preferred adsorption at the oil/water interfaces in rock pores was not achieved. A major improvement in surface coating optimization is achieved by creating a crosslinked polymer film that wraps around the nanoparticle so that it does not detach from the particle surface even under the harsh reservoir conditions. To fine-tune the coating to satisfy the reservoir application requirements, co-polymers and ter-polymers with different constituent monomers are employed. Nanoparticles stabilized with (poly-styrene sulfonate–alt-maleic acid) coating show a good adsorption tendency at the oil/water interfaces, while with very low adsorption at rock surface (~0.02 mg/m2). The dispersion also has long-term stability even at high salinity (8 wt% NaCl). Other polymers, such as (polyacrylic acid–r-butyl acrylate), (polyacrylic acid–b-styrene sulfonic acid), and (polyacrylic acid–r-butyl acrylate–b-styrene sulfonic acid), were also tested. The coating with the last polymer (PAA–PBA–PSS) provides a very low retention of particles in the rock, but only marginal preferred adsorption at oil/water interfaces.
pSS-alt-pMA co-polymer coating to paramagnetic nanoclusters (TEM image) provides good reservoir transportability (blue effluent curve) and preferential adsorption of nanoclusters to oil/water interfaces (red curve).
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
Description of the material. Stable CO2/water (C/W) foams at high temperatures and salinities have been achieved with substituted amines in limestone, sandstone and glass bead packs with permeabilities from 1 to 78 Darcy. Foams were formed upon injection of the CO2 soluble surfactant in the CO2 phase and would be beneficial for improving sweep efficiency in EOR process.Application. Despite significant interest in CO2 foams for EOR, very few studies have reported stable foams at high temperatures (120 °C) and high salinities, which are often encountered in the Middle East and elsewhere. The foams provide mobility control and stabilize the displacement front in CO2flooded zones to improve sweep efficiency.Results, Observations, Conclusions. The amine surfactants are switchable between the nonionic and cationic states with pH or the nature of the solvent. They exhibit nonionic behavior when introduced in the CO2 phase, which favors injectivity, and cationic in the presence of concentrated brine with dissolved CO2. The hydrophilic/lipophilic balance of the amines was tuned by modification of the amine head group or tail length to design strong foams. It was important to increase the basicity of surfactants to enhance the solvation in the aqueous phase over a pH range of 4 to 7. These surfactants were effective in lowering the interfacial tension between water and CO2 at high temperature and salinity. They generated viscous C/W foams in limestone, sandstone and glass bead packs at 120 °C in the presence of 22% TDS brine when surfactants were injected from either the aqueous or CO2 phase. At pH below 6, these surfactants exhibited low oil/water partition coefficients on the order of 0.1 which suggests that these surfactants will have minimal retardation due to partitioning into oil in the EOR process.Significance of Subject Matter. These surfactants stabilized C/W foam at high temperature and salinity, and partitioned to the water phase over dodecane phase for efficient surfactant utilization. The high solubility in CO2 is beneficial for the surfactant to be available along CO2 flow pathways in a reservoir to minimize viscous fingering and gravity override.