Publications by Year: 2014

J. R. Laber, Borwankar, A. U., Maynard, J. A., Truskett, T. M., and Johnston, K. P., “Biochemical characterization of the low viscosity reversible protein nanocluster platform,” ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY, vol. 247. AMER CHEMICAL SOC 1155 16TH ST, NW, WASHINGTON, DC 20036 USA, 2014.
J. Dong, Worthen, A. J., Chen, Y., Foster, L. M., Bollinger, J. A., Truskett, T. M., Bryant, S. L., Bielawski, C. W., and Johnston, K. P., “Effective oil dispersible clay-based dispersant systems for oil-in-seawater emulsions,” ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY, vol. 247. AMER CHEMICAL SOC 1155 16TH ST, NW, WASHINGTON, DC 20036 USA, 2014.
R. I. Stover, Murthy, A., Gourisankar, S., Ne, G., Martinez, M., Truskett, T., Sokolov, K., and Johnston, K., “Biodegradable gold nanoclusters which exhibit high-NIR absorbance for biomedical imaging,” ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY, vol. 247. AMER CHEMICAL SOC 1155 16TH ST, NW, WASHINGTON, DC 20036 USA, 2014.
B. J. Dear, Borwankar, A. U., Hung, J., Wilson, B. K., Dahotre, S. N., Maynard, J. A., Truskett, T. M., and Johnston, K. P., “Low viscosity reversible protein nanocluster dispersions with tunable sizes,” ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY, vol. 247. AMER CHEMICAL SOC 1155 16TH ST, NW, WASHINGTON, DC 20036 USA, 2014.
J. J. Hung, Dinn, A. K., Borwankar, A. U., Dear, B. J., Wilson, B. K., Twu, A., Yue, J., Maynard, J. A., Truskett, T. M., and Johnston, K. P., “Self-assembly of tunable protein nanoclusters with molecular crowding agents (depletants),” ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY, vol. 247. AMER CHEMICAL SOC 1155 16TH ST, NW, WASHINGTON, DC 20036 USA, 2014.
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.
K. Johnston, Chen, Y., Elhag, A., Worthen, A., Xue, Z., Foster, E., Foster, L., Hirsaki, G., Biewlawski, C., and Nguyen, Q., “Design of surfactants and nanoparticles for CO2 sequestration, enhanced oil recovery, and electromagnetic imaging,” ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY, vol. 247. AMER CHEMICAL SOC 1155 16TH ST, NW, WASHINGTON, DC 20036 USA, 2014.
A. S. Elhag, Chen, Y., Chen, H., Reddy, P. P., Cui, L., Worthen, A. J., Ma, K., Hirasaki, G. J., Nguyen, Q. P., and Biswal, S. L., “Switchable amine surfactants for stable CO2/brine foams in high temperature, high salinity reservoirs,” SPE Improved Oil Recovery Symposium. Society of Petroleum Engineers, 2014. Publisher's VersionAbstract
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.
Y. Chen, Elhag, A. S., Poon, B. M., Cui, L., Ma, K., Liao, S. Y., Reddy, P. P., Worthen, A. J., Hirasaki, G. J., and Nguyen, Q. P., “Switchable nonionic to cationic ethoxylated amine surfactants for CO2 enhanced oil recovery in high-temperature, high-salinity carbonate reservoirs,” SPE Journal, vol. 19, no. 02, pp. 249-259, 2014. Publisher's VersionAbstract
To improve sweep efficiency for carbon dioxide (CO2) enhanced oil recovery (EOR) up to 120°C in the presence of high-salinity brine (182 g/L NaCl), novel CO2/water (C/W) foams have been formed with surfactants composed of ethoxylated amine headgroups with cocoalkyl tails. These surfactants are switchable from the nonionic (unprotonated amine) state in dry CO2 to cationic (protonated amine) in the presence of an aqueous phase with a pH less than 6. The high hydrophilicity in the protonated cationic state was evident in the high cloudpoint temperature up to 120°C. The high cloudpoint facilitated stabilization of lamellae between bubbles in CO2/water foams. In the nonionic form, the surfactant was soluble in CO2 at 120°C, and 3,300 psia at a concentration of 0.2% (w/w). C/W foams were produced by injecting the surfactant into either the CO2 phase or the brine phase, which indicated good contact between phases for transport of surfactant to the interface. Solubility of the surfactant in CO2 and a favorable C/W partition coefficient are beneficial for transport of surfactant with CO2-flow pathways in the reservoir, to minimize viscous fingering and gravity override. The ethoxylated cocoamine with two ethylene oxide (EO) groups was shown to stabilize C/W foams in a 30-darcy sandpack with NaCl concentrations up to 182 g/L at 120°C, 3,400 psia, and foam qualities from 50 to 95%. The foam produces an apparent viscosity of 6.2 cp in the sandpack and 6.3 cp in a 762-µm-inner-diameter capillary tube (downstream of the sandpack) in contrast with values well below 1 cp without surfactant present. Moreover, the cationic headgroup reduces the adsorption of ethoxylated alkyl amines on calcite, which is also positively charged in the presence of CO2 dissolved in brine. The surfactant partition coefficients (0 to 0.04) favored the water phase over the oil phase, which is beneficial for minimizing losses of surfactant to the oil phase for efficient surfactant usage. Furthermore, the surfactant was used to form C/W foams, without forming stable/viscous oil/water (O/W) emulsions. This selectivity is desirable for mobility control whereby CO2 will have low mobility in regions in which oil is not present and high contact with oil at the displacement front. In summary, the switchable ethoxylated alkyl amine surfactants provide both high cloudpoints in brine and high interfacial activities of ionic surfactants in water for foam generation, as well as significant solubilities in CO2 in the nonionic dry state for surfactant injection
R. Stover, Murthy, A., Gourisankar, S., Nie, G., Martinez, M., Truskett, T., Sokolov, K., and Johnston, K., “Plasmonic biodegradable gold nanoclusters with high NIR-absorbance for biomedical imaging,” SPIE BiOS. International Society for Optics and Photonics, pp. 89550T-89550T-7, 2014. Publisher's VersionAbstract
Gold plasmonic nanoparticles are receiving attention for a variety of types of NIR optical biomedical imaging including photoacoustic imaging. Herein we present a novel method to assemble equilibrium gold nanoclusters from 5 nm primary gold nanospheres, which exhibit high near-infrared (NIR) absorbance and subsequently fully dissociate back to primary particles, which has the potential to enable renal clearance. The nanoparticle assembly is manipulated via controlling colloidal interactions, specifically electrostatic repulsion and depletion attraction. The charge on the primary ~5 nm gold nanospheres is tailored via place exchange reactions with a variety of biocompatible ligands such as citrate, lysine and cysteine. The primary particles form clusters upon addition of a biodegradable polymer, PLA(1k)-b- PEG(10k)-b-PLA(1k), followed by controlled solvent evaporation. The cluster size may be tuned from 20-40 nm in diameter by manipulating the gold and polymer concentrations along with the solvent evaporation extent. Salt is also added to increase the NIR absorbance and reduce the nanocluster size by reducing polymer adsorption. The adsorption of the polymer onto the Au surfaces effectively quenches the nanoclusters. High NIR absorption facilitates photoacoustic imaging, even for the small cluster sizes. In response to acidic cellular pH environments, the polymer degrades and the clusters dissociate back to primary particle on the order of 5 nm, which are small enough for renal clearance. © (2014) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only
A. J. Worthen, Foster, L. M., Dong, J., Bollinger, J. A., Peterman, A. H., Pastora, L. E., Bryant, S. L., Truskett, T. M., Bielawski, C. W., and Johnston, K. P., “Synergistic formation and stabilization of oil-in-water emulsions by a weakly interacting mixture of zwitterionic surfactant and silica nanoparticles,” Langmuir, vol. 30, no. 4, pp. 984-994, 2014. Publisher's VersionAbstract
Oil-in-water emulsions were formed and stabilized at low amphiphile concentrations by combining hydrophilic nanoparticles (NPs) (i.e., bare colloidal silica) with a weakly interacting zwitterionic surfactant, caprylamidopropyl betaine, to generate a high hydrophilic–lipophilic balance. The weak interaction of the NPs with surfactant was quantified with contact angle measurements. Emulsions were characterized by static light scattering to determine the droplet size distributions, optical photography to quantify phase separation due to creaming, and both optical and electron microscopy to determine emulsion microstructure. The NPs and surfactant acted synergistically to produce finer emulsions with a greater stability to coalescence relative to the behavior with either NPs or surfactant alone. As a consequence of the weak adsorption of the highly hydrophilic surfactant on the anionic NPs along with the high critical micelle concentration, an unusually large surfactant concentration was available to adsorb at the oil–water interface and lower the interfacial tension. The synergy for emulsion formation and stabilization for the two amphiphiles was even greater in the case of a high-salinity synthetic seawater aqueous phase. Here, higher NP adsorption at the oil–water interface was caused by electrostatic screening of interactions between (1) NPs and the anionic oil–water interface and (2) between the NPs. This greater adsorption as well as partial flocculation of the NPs provided a more efficient barrier to droplet coalescence
A. J. Worthen, Parikh, P. S., Chen, Y., Bryant, S. L., Huh, C., and Johnston, K. P., “Carbon Dioxide-in-Water Foams Stabilized with a Mixture of Nanoparticles and Surfactant for CO2 Storage and Utilization Applications,” Energy Procedia, vol. 63, pp. 7929-7938, 2014. Publisher's VersionAbstract
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.
A. S. Elhag, Chen, Y., Reddy, P. P., Noguera, J. A., Ou, A. M., Hirasaki, G. J., Nguyen, Q. P., Biswal, S. L., and Johnston, K. P., “Switchable diamine surfactants for CO2 mobility control in enhanced oil recovery and sequestration,” Energy Procedia, vol. 63, pp. 7709-7716, 2014. Publisher's VersionAbstract
The design of switchable amine surfactants for CO2 EOR in carbonate reservoirs at high temperatures is challenging because of the increase in the pH due to dissolution of calcium carbonate at acidic conditions. The increased pH hinders the protonation of the surfactant and its aqueous solubility. In this work, the addition of a second amine headgroup ensured that C16-18 N(EO) C3N(EO)2 is soluble in 22%TDS brine at neutral pH conditions. Also, captive bubble tensiometry measurements confirmed the activity of the surfactant at the C-W interface by large reduction in the interfacial tension coupled with high adsorption. Also, the surfactant generated viscous foam that can stabilize the displacement front in CO2 EOR processes and decrease the mobility of CO2 for enhanced CO2 sequestration
G. Yu, Dong, J., Foster, L. M., Metaxas, A. E., Truskett, T. M., and Johnston, K. P., “Breakup of oil jets into droplets in seawater with environmentally benign nanoparticle and surfactant dispersants,” Industrial & Engineering Chemistry Research, vol. 54, no. 16, pp. 4243-4251, 2014. Publisher's VersionAbstract
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
T. Zhang, Murphy, M. J., Yu, H., Bagaria, H. G., Yoon, K. Y., Nielson, B. M., Bielawski, C. W., Johnston, K. P., Huh, C., and Bryant, S. L., “Investigation of nanoparticle adsorption during transport in porous media,” SPE Journal, 2014. Publisher's VersionAbstract
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
L. M. Foster, Worthen, A. J., Foster, E. L., Dong, J., Roach, C. M., Metaxas, A. E., Hardy, C. D., Larsen, E. S., Bollinger, J. A., and Truskett, T. M., “High interfacial activity of polymers “grafted through” functionalized iron oxide nanoparticle clusters,” Langmuir, vol. 30, no. 34, pp. 10188-10196, 2014. Publisher's VersionAbstract
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
E. L. Foster, Xue, Z., Roach, C. M., Larsen, E. S., Bielawski, C. W., and Johnston, K. P., “Iron oxide nanoparticles grafted with sulfonated and zwitterionic polymers: High stability and low adsorption in extreme aqueous environments,” ACS Macro Letters, vol. 3, no. 9, pp. 867-871, 2014. Publisher's VersionAbstract
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
K. P. Johnston, Mazuski, M. A., Engstrom, J., and Rodrigues, M. A., “Low viscosity highly concentrated suspensions”. US Patent 8,779,094, 2014. Publisher's VersionAbstract
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.
J. Dong, Worthen, A. J., Foster, L. M., Chen, Y., Cornell, K. A., Bryant, S. L., Truskett, T. M., Bielawski, C. W., and Johnston, K. P., “Modified montmorillonite clay microparticles for stable oil-in-seawater emulsions,” ACS applied materials & interfaces, vol. 6, no. 14, pp. 11502-11513, 2014. Publisher's VersionAbstract
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
T. J. Mefford, Hardin, W. G., Dai, S., Johnston, K. P., and Stevenson, K. J., “Anion charge storage through oxygen intercalation in LaMnO3 perovskite pseudocapacitor electrodes,” Nature materials, vol. 13, no. 7, pp. 726-732, 2014. Publisher's VersionAbstract
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