Incorporating ions within electrodeposited polymer dielectric films creates ultrathin solid electrolytes on a length scale (<50 nm) that bridges molecular electronics and conventional electrochemical devices. Electrooxidation of phenol in basic acetonitrile generates electrodeposited nanoscale (21 ± 2 nm), pinhole-free poly(phenylene oxide), PPO, films on indium−tin-oxide substrates. Solid-state electrical measurements using top electrode contacts (vapor-deposited Au, liquid Hg, or liquid Ga−In eutectic) confirm that these PPO films are electronically insulating (7 ± 2 × 10-12 S cm-1) with a high dielectric strength (1.7 ± 0.1 × 106 V cm-1). The insulating film is converted to an ultrathin solid polymer electrolyte by soaking in a solution of LiClO4−propylene carbonate and then heating under vacuum to remove solvent. Atomic force microscopy establishes that the salt-impregnated film is thicker (43 ± 10 nm) than the as-prepared PPO film. The X-ray photoelectron spectroscopic measurements suggest minimal retention of solvent in the film. Electrochemical impedance measurements demonstrate that the incorporated ions are mobile in the solid state with an ionic conductivity of 7 ± 4 × 10-10 S cm-1. Such ultrathin solid polymer electrolytes should enable progress toward nanoscopic solid-state ionic devices and power sources.

Measurements of the electrical conductivity and proton and fluorine-19 NMR spin−lattice relaxation times (T 1) in acid form NAFION 105, 117, and 120 conditioned at various levels of relative humidity have been carried out. Complex impedance studies were made along the plane of the polymer film at frequencies from 10 to 108 Hz at room temperature and pressures up to 0.3 GPa. The NMR measurements were made at room temperature and pressures up to 0.25 GPa. Both types of measurement were also carried out on various concentrations of sulfuric acid in water. The electrical conductivity decreases with increasing pressure for low water content acid solutions and low water content NAFION samples. This behavior (positive activation volumes) is that expected for “normal” liquids and for ions in polymers where the motion of the ions is determined by the host matrix. However, for high water contents, the reverse is true. The electrical conductivity increases with increasing pressure which gives rise to a negative activation volume. The results show that at high water contents, the electrical conductivity mechanism in NAFION is essentially identical to that for a dilute acid where the transport is controlled by the aqueous component. The activation volumes extracted from the proton NMR T 1 data are in qualitative agreement with those obtained from the electrical conductivity measurements at intermediate and low water contents, suggesting that motion of the sulfonic acid-terminated pendant chains contributes to the conduction mechanism at low water contents.

The Johari-Goldstein (JG) secondary relaxation, presumed to be universal, has never been seen in 1,4-polyisoprene (PI) by dielectric spectroscopy, despite very many measurements extending over the past half-century. By using a high-resolution capacitance bridge, we are able to show the existence of a secondary relaxation in PI that has the properties of the JG process. Measurements were also carried out at lower temperatures, which probe the dynamics of chain units "caged" by neighboring segments comprising the local structure. The caged dynamics precede by decades of time the JG relaxation and, from general physical principles, are also expected to be a property of all glass-forming materials. Collectively, the caged dynamics and JG relaxation serve as precursors to structural relaxation (i.e., the glass transition) and thus are of central importance to understanding vitrification. The present data show that the dynamics of caged PI repeat units are manifested as a nearly constant loss (NCL). This NCL has been found in other glass-formers, both molecular and polymeric, and its temperature dependence in PI is similar to that for other materials. The experimental results are consistent with the predictions from the coupling model.

Subambient thermal decomposition of ruthenium tetroxide from nonaqueous solution onto porous SiO(2) substrates creates 2-3 nm thick coatings of RuO(2) that cover the convex silica walls comprising the open, porous structure. The physical properties of the resultant self-wired nanoscale ruthenia significantly differ depending on the nature of the porous support. Previously reported RuO(2)-modified SiO(2) aerogels display electron conductivity of 5 x 10(-4) S cm(-1) (as normalized to the geometric factor of the insulating substrate, not the conducting ruthenia phase), whereas RuO(2)-modified silica filter paper at approximately 5 wt % RuO(2) exhibits approximately 0.5 S cm(-1). Electron conduction through the ruthenia phase as examined from -160 to 260 degrees C requires minimal activation energy, only 8 meV, from 20 to 260 degrees C. The RuO(2)(SiO(2)) fiber membranes are electrically addressable, capable of supporting fast electron-transfer reactions, express an electrochemical surface area of approximately 90 m(2) g(-1) RuO(2), and exhibit energy storage in which 90% of the total electron-proton charge is stored at the outer surface of the ruthenia phase. The electrochemical capacitive response indicates that the nanocrystalline RuO(2) coating can be considered to be a single-unit-thick layer of the conductive oxide, as physically stabilized by the supporting silica fiber.

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