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A simple model for surfactants in solution is used to investigate the effect of diblock spacer molecules on the structure of micellar systems. The solvent is modeled by a simple Lennard-Jones fluid and the surfactants and spacer molecules are modeled by chains of Lennard-Hones sites connected by simple harmonic bonds. The surfactant is modeled as a solventphobic tail attached to a single solventphilic head site; the spacer is modeled as a solventphobic tail attached to a chain of solventphilic head sites. Molecular dynamics simulations on large systems ({approximately}40 000 particles) are performed to investigate the properties of the model. The strength of the interaction between the solventphilic portion of the spacer and the solvent and the effect of the length of both the solventphobic and the solventphilic portions of the spacer on the structure of the micelle solution are investigated. The simulations suggest that for the spacer to keep micelles apart, the interaction between the solvent and solventphilic portion of the spacer must be fairly strong. Weak interactions between the solventphilic portion of the spacer and the solvent cause the spacer to collapse on the surface of the micelle.

Onboard hydrogen generation using compact plasmatron devices could provide important new possibilities for reducing pollution from motor vehicles, making use of alternative fuels, and increasing engine efficiency. These improvements would involve the use of the plasmatron as a very small, rugged, rapid response and highly flexible means of electrical heating of gases. Plasmatron heating could be used to facilitate conversion of a wide range of hydrocarbon fuels into hydrogen-rich gas onboard a vehicle. Use of combinations of fuels is possible through potential transformation of a variety of fuels into hydrogen-rich gas. Another advantage of use of onboard plasmatron generation of hydrogen is that it could be used only when required and could be readily turned on and off. Preliminary experimental studies of plasmatron conversion of difficult-to-use alternative fuels (biofuels), iso-octane (representative of gasoline), and diesel fuel are described. Concepts for application to trucks and other heavy duty vehicles, sport utility vehicles and automobiles are discussed.

Cyclic polarization of TiN electrodes in 6 M KOH at room temperature revealed relatively large anodic and cathodic overpotentials for water decomposition that depend on the surface structure of the material. Polished TiN electrodes also underwent a slow reaction during anodic polarization above the reversible potential for O{sub 2} evolution that involved the formation of a reaction product film. The film was uniform over the surface of the electrodes and contained hydrous potassium titanate. A corrosion product, similar in composition but less uniform in appearance, formed on TiN after 4 months under open-circuit conditions in the same solution. Results indicate that the film forms slowly by a dissolution/precipitation mechanism and that the dissolution step gives rise to an oxidation peak observed in the cyclic voltammogram during anodic polarization. Since the film forms above the reversible potential for O{sub 2} evolution and since the overvoltage for O{sub 2} evolution depends on surface structure, it is not yet clear whether the formation of the corrosion film will compete with electrolysis reactions during the charging of structurally tailored, high surface area, TiN electrodes that are under development for ultracapacitor applications.

The self-assembly process provides an effective and environmentally benign method for synthesizing novel ceramic and composite materials. Three different approaches are discussed in this article: (1) self-assembly of colloidal crystals, (2) self-assembled monolayers, and (3) three-dimensional self-assembly with amphiphilic molecules. The self-assembly of colloidal crystals allows the synthesis of periodic optical devices and quantum dots from simple monodispersed particles. Self-assembled monolayers provide a molecular template to control the nucleation and growth of ceramic thin films. The emphasis of this paper will be on the self-assembly process with amphiphilic molecules, which represents the latest breakthrough in the design and synthesis of tailored nanoscale materials and composites. In the past few years, self-assembled materials have become a very active research area. This article illustrates how the basic principles of self-assembly can be applied in the synthesis of ceramic materials and discusses the role of various inter-molecular and into-particular forces.

A new mesoporous structure, silicate spherulite, has been produced in dilute surfactant and silicate solutions. The spherulites were formed from radially arranged rod-like micelles. The surfactant molecules in the rod-like micelles can be removed by heat treatment to leave a unique mesoporous material with radially arranged channels for easy access. Although the spherulite morphology has been observed in the nucleation and growth of polymeric crystals for a long time, it has not been reported in surfactant solutions. Similar to the polymeric materials, the surfactant spherulites are most likely the fingerprints of the early nucleation process in the preparation of ordered mesophase silicates.

This paper investigates the effect of hydrolysis and the formation of hydrated polycations on the colloidal stability and rheological properties of fine alumina suspensions. This is an important phenomenon in colloidal processing of advanced ceramic materials and nanocomposite materials from fine particles. The aging process and the formation of large polycations in the solution are monitored by nuclear magnetic resonance, and the aggregation rate and viscosity of the suspension are measured under similar conditions. It is observed that aging under acidic conditions increases colloidal stability against aggregation in dispersed suspensions, and reduces the viscosity in flocculated suspensions. This behavior corresponds well to the formation of large polynuclear species through hydrolysis. It is suggested that the hydrated polycations significantly modify the total interaction energy between two particles at short separation distances.

This research investigates the effect of colloidal particles on the preparation of ordered mesoporous materials (M41S). It demonstrates that colloidal silica and colloidal titania particles promote the formation of these materials. Under similar conditions no ordered structure is observed without the colloidal particles. A heterogeneous nucleation mechanism is proposed based on these observations and is supported by direct evidence from transmission electron microscopy (TEM). 15 refs., 5 figs.

Steric stabilization of small unilamellar vesicles composed of dipalmitoyl phosphatidylglycerol (DPPG) is achieved by the incorporation of nonylphenol poly(ethylene oxide) ethers at varying mol%. Nonylphenol poly(ethylene oxide) ethers with an average of either 10.8 (NP 10 or 50 (NP 50 ethylene oxide groups are incorporated into vesicles at between 2.5 and 10 mol%. Vesicle aggregation is induced by the addition of either NaCl or CaCl 2 with the effective diameter of the vesicle dispersion measured as a function of time using photon correlation spectroscopy. The addition of between 5 and 20 mol% NP 10 to DPPG vesicles increases dispersion stability 10-fold in the presence of NaCl but only 2-fold in the presence of CaCl 2 . Dispersion stability is increased 100-fold with the addition of 10–20 mol% NP 50 in NaCl and 1000-fold in the presence of CaCl 2 . Vesicle aggregation is found to be reversible with 5 mol% added NP 50 in NaCl but only partially reversible in the presence of CaCl 2 . The hydrophobic nonylphenol moiety of NP 50 is found to be critical for imparting dispersion stability when compared to the addition of pure poly(ethylene oxide) to vesicles.

An expression is derived relating the rate constant for doublet formation to the experimentally measured rate of change of the intensity-weighted mean particle radius, at early times, determined from photon correlation spectroscopy (PCS). The rate constant for doublet formation is proportional to a derived “optical factor” that is a function of particle size, scattering angle, and wavelength of light in the dispersing medium. The optical factor is calculated using form factors from Rayleigh-Debye theory and diffusion coefficients from Kirkwood-Riseman theory. Estimation of the rate constant for doublet formation using early-time PCS measurements suggests that particle concentrations no greater than 10 9 particles/cm 3 should be used.

Setting the Foundation for Transforming the U.S. Energy System: Three Federal Action Plans for Near- and Long-term Success is a short document written for the incoming U.S. Federal Administration's Transistion Team. The document represents what we believe to be foundational elements of a broad campaign to make rapid progress towards these goals for the longterm transformation necessary to meet our national economic, security, and environmental goals. The three immediate action plans include: * Creating Tomorrow’s Electricity Infrastructure * Decarbonizing the Energy Economy *Enabling Science-Based Policy

Energy storage will play a critical in the electrification of the transportation industry and modernization of the power grid infrastructure. Currently, many technologies are investigated, including Li-ion, redox flow, Li and Na sulfur batteries. Li-ion batteries have attracted wide attention for automobile applications, and redox flow, sodium and new sulfur chemistries are under intense development. Significant breakthroughs in performance, cost and safety is needed to meet the requirement of various applications, but no single technology will be able to address all the challenges. This seminar will summarize our recent progress in developing analytical tools to understand the energy storage requirements for balancing service and other applications in different regions in the United States, and the cost and life cycle requirements for such applications. The current status, advantages and limitations of some key technologies will be discussed. This seminar will also discuss our recent breakthroughs in a new generation of low cost, redox flow batteries that can increase the energy density by several times, and Na batteries that can operate at temperatures at below 100°C.

Recently we proposed that heterogenous nucleation is an important phenomenon for the preparation of ordered mesoporous materials. In this paper we further investigate the effect of colloidal particles on the nucleation process of mesoporous materials. Based on the change of the electrical mobilities of the particles in the surfactant solution, we suggest that the adsorption and co-adsorption of surfactant and ceramic precursors changes local structural and chemistry on the particle surfaces, and favors the nucleation events within these regions.

A non-aqueous synthesis route broadens the spectrum of useful precursors and the range of compositions which can be achieved in the synthesis of ordered, mesoporous multicomponent materials. A formamide solution of surfactant (cetyltrimethylammonium chloride/hydroxide) allows for distribution of a water-sensitive metal oxide precursor prior to reaction. Hydrolysis of the metal oxide precursor and phase separation to the pure oxide are controlled by adding limited amounts of water. Subsequent addition of a second metal oxide source as an aqueous solution initiates the reactions leading to a mixed oxide having ordered mesopores. Ordered mesoporous titanium silicates having final Ti/Si mole ratios in excess of 1/20 are synthesized.

Two aspects of phospholipid vesicle aggregation are examined: the low rate at which it occurs, even at high electrolyte concentrations, and its unusual temperature dependence. A comparison of experimental data with theoretical calculations suggests that phospholipid vesicles aggregate into a shallow minimum, resulting in weak, reversible aggregation. The incorporation of a hydration effect gives the total interaction potential the necessary features for such behavior. The temperature dependence of the aggregation kinetics appears to result from a temperature dependence of the effective Hamaker constant and the hydration parameters.