We report a new surface-initiated polymerization strategy that yields superhydrophobic polymethylene (PM) films from initially smooth substrates of gold and silicon. The films are prepared by assembling a vinyl-terminated self-assembled monolayer, followed by exposure of the surface to a 0.1 M solution of borane, and polymerizing from the borane sites upon exposure to a solution of diazomethane at -17 degrees C. Surface-initiated polymethylenation (SIPM) presents rapid growth in relation to other surface-initiated reactions, producing PM films thicker than 500 nm after 2 min of reaction and 3 microm after 24 h of reaction. AFM and SEM images show the presence of micro- and nanoscale features that enable the entrapment of air when exposed to water. Consistent with this result, these films exhibit advancing water contact angles greater than 160 degrees, dramatically different than 103 degrees measured for smooth PM films, and hysteresis values ranging from 2 degrees to 40 degrees, depending on the substrate and polymerization time. The superhydrophobic character of the films results in the entrapment of air at the polymer/solution interface to provide remarkable resistances greater than 10(10) Omega x cm(2) against the transport of aqueous redox probes and cause the film to behave as a "perfect" capacitor.

Superhydrophobic polymethylene (PM) films provide remarkable protection against the transport of aqueous redox probes as a result of entrapped air at the water/polymer interface. The wetting properties and the topography for a set of superhydrophobic (SH) and nonsuperhydrophobic (NSH) PM films were established to compare their interfacial behavior using electrochemical impedance spectroscopy (EIS). EIS results show that SH PM films exhibit resistances against ion transfer that are approximately 3 orders of magnitude higher than those of NSH PM films. Rationalization of these results in the context of the Helmholtz theory reveals that the imaginary impedance or inverse capacitance of SH PM films exhibits positive deviations from that predicted by Helmholtz theory for smooth PM films. Here, we model the capacitance behavior of a SH film as a PM/air composite that acts as a circuit of capacitors. The resulting mathematical model of this analysis enables correlation of the effective dielectric properties of the film (d(effective), epsilon(effective)) to measurable properties such as thickness (d(film)) and the dielectric constant (epsilon(PM)) of the PM film. Finally, a sensitivity analysis shows that the limited contact area between the aqueous solution and PM in SH films is the primary reason for the enhancement in the barrier properties of the film.

High-pressure oxygen is an integral part of fuel cell systems, many NASA in situ resource utilization concepts, and life support systems for extravehicular activity. Due to the limited information available for system designs over wide ranges of temperature and pressure, volumetric methods are applied to measure adsorption isotherms of O(2) and N(2) on NaX and NaY zeolites covering temperatures from 105 to 448 K and pressures up to 150 bar. Experimental data measured using two apparatuses with distinctly different designs show good agreement for overlapping temperatures. Excess adsorption isotherms are modeled using a traditional isotherm model for absolute adsorption with a correction for the gas capacity of the adsorption space. Comparing two models with temperature-dependent coefficients, a virial isotherm model provides a better description than a Toth isotherm model, even with the same number of parameters. With more virial coefficients, such as a cubic form in loading and quadratic form in reciprocal temperature, the virial model can describe all data accurately over wide ranges of temperature and pressure.

We have found that the addition of low concentrations of certain inexpensive light cosolvents to alkaline/polymer (AP) solutions dramatically improves the performance of AP corefloods in two important ways. First, the addition of cosolvent promotes the formation of low-viscosity microemulsions rather than viscous macroemulsions. Second, these light cosolvents greatly improve the phase behavior in a way that can be tailored to a particular oil, temperature, and salinity. This new chemical enhanced-oil-recovery (EOR) technology uses polymer for mobility control and has been termed alkali/cosolvent/polymer (ACP) flooding. ACP corefloods perform as well as alkaline/surfactant/polymer (ASP) corefloods while being simpler and more robust. We report 12 successful ACP corefloods using four different crude oils ranging from 12 to 24 API. The ACP process shows special promise for heavy oils, which tend to have large fractions of soap-forming acidic components, but is applicable across a wide range of oil gravity.

Alkali flooding in heavy oil reservoirs is known to stabilize emulsion in-situ and improve the recovery beyond that of conventional waterflood under certain boundary and initial conditions. The overarching goal of this study is to develop a systematic approach to optimize this process and capture underlying recovery mechanisms. Therefore, we experimentally evaluated the performance of alkali flood as a function of emulsion type and viscosity. Phase behavior and viscosity of the microemulsion are modified by introducing seven different surfactants. Microscope imaging techniques are employed to measure the droplet size distribution for type I and II emulsions. Viscosities of generated emulsions are measured with a rotational rheometer at low temperatures and with an electromagnetic viscometer at reservoir conditions. Finally, corefloods are conducted at different conditions to evaluate the performance of displacement as a function of emulsion type and viscosity. Enhanced alkali floods showed an incremental recovery of 8 – 50% beyond that of waterflood. Formation of higher viscosity emulsion has a large contribution on the sweep efficiency and therefore improved oil recovery during alkali flood; however, other mechanisms (e.g. entrainment and entrapment) also have contribute to the incremental recovery. Results of our experiments indicated that the incremental recovery is a strong function of emulsion type, emulsion viscosity, and the droplet size distribution.