PEO‐normalLiX false(X=CF3SO3−,ClO4−,and AsF6−false) systems have been characterized by x‐ray diffraction and optical microscopy, and the resulting phase diagrams are taken into account for the interpretation of ac impedance measurements. Eutectic reactions and multiple‐intermediate‐compound formation are characteristic of most systems. Simple phenomenological models do not explain the overall conductivity behavior. The activation energy of ion transport is independent of the anion, and remains mainly constant at 0.7 eV over the concentration range studied for T>60°C . Ion‐pair formation seems to occur at low salt concentration.

Results of the physicochemical characterization of poly(ethylene oxide)-sodium iodide polymer electrolytes by DSC, WAXS, microscopy, and ac conductivity, together with the values of transition temperatures reported in the literature, led to the determination of a phase diagram for this system. A study of the transport properties, based on ac impedance measurements of the total ionic conductivities and on measurement of the ionic diffusion coefficients by radiotracer, shows a predominant anionic mobility for amorphous single-phase PEO-NaI electrolytes. The mechanism proposed for the ionic transport process implies that associations are formed between ions. This associative process may determine the value of the apparent activation energy terms of the measured ionic diffusion coefficients. ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 128.122.253.228 Downloaded on 2015-05-27 to IP

The changes in thermal and mechanical properties produced by complexation with NaSCN of a polyethylene oxide-b-isoprene-b-ethylene oxide) (PEO-PI-PEO) block polymer are described. The number-average molecular weight of the PEO-PI-PEO polymer was 1.67 X 105, and its PEO weight fraction was 0.14. It is shown that complexation, which occurs selectively with the PEO end blocks, can yield a semicrystalline thermoplastic elastomer that melts at about 450 K. The main characteristics of the complexed block polymer are a crystallization temperature, which occurs 90 K lower than that of complexed homo-PEO, and good dimensional stability at high temperature. However, the tensile strength of the complexed material appears to be considerably reduced with increasing temperature. A pronounced supercooling was also observed for the uncomplexed PEO-PI-PEO block polymer. This phenomenon seems to be a general feature of two-phase block polymers in which the crystallizable component is finely dispersed into isolated microdomains.

While the concentration of airborne particulate matter is well-known to be correlated with people's health, a chemical evaluation must also be important. Noting that airborne dust particles in the 3À5 μm size regime are among the largest that get into people's lungs, such particles were collected by pumping air through plasmonic metal films with a 12.6 μm square lattice of 5 μm square holes. Capture of a dust particle in a metallic hole enables the recording of "scatter-free" infrared absorption spectra whose peaks reveal the infrared active components. The study of the spectra of individual particles allows minority components to be characterized in a way that is quite incisive which is difficult with bulk samples. A library of 63 spectra of individual particles captured from our laboratory air is presented along with a preliminary analysis of the contributing components.

The melting behavior of series of solvent-cast mixtures of a low molecular weight (a,, = 4 Y . lo3) poly(ethy1ene oxide) (PEO) with NaSCN and KSCN has been studied by DSC and optical microscopy.The results show great similarities between the two systems. Their common characteristics are f i t the formation of a single solid compound, P(E03.NaSCN) and P(EO,,.KSCN), that melts incongruently to yield the solid salt and a peritectic liquid and second a liquid-liquid miscibility gap occurring at the melting point of the pure salt. Both systems exhibit a nearly vertical salt liquidus curve, indicating that complex formation also takes place in the liquid phase. The stoichiometry of the solvate is close to 4/1 for NaSCN and 5/1 for KSCN. The mixtures with NaSCN were highly crystalline over the whole composition range while those with KSCN showed either partial crystallinity or the absence of crystallinity at PEO contents above that of the solid compound. Because of the peritectic reaction, in either system the solid compound cannot participate in the formation of a eutectic mixture with the solid salt. In turn, it can form a eutectic mixture with solid PEO. In the case of the PEO-NaSCN system for which the construction of a complete phase diagram was possible, the eutectic composition is close to 93% by weight in PEO with a corresponding tie line located 4 "C below the melting point of pure PEO. The analysis of the P(E03-NaSCN) liquidus curve in terms of the Flory-Huggins thermodynamic concepts indicates the presence of a strong exothermic interaction (x = -1.2), associated with the solvation of P(E03.NaSCN) by PEO yielding the solvate P(EO,.NaSCN). For either system, the reverse path of the peritectic reaction is not quantitative for a mixture having the composition of the solid compound. In either case, melt recrystallization yields a material that contains the solid salt in addition to the solid compound.ABSTRACT: 2,2'-Azobis([ 2-13C]propionitrile) (1) was prepared in 35% overall yield starting from [ 1-'3C]-acetaldehyde (99 atom 7%). Quantitative I3C NMR analysis of end groups in styrene-acrylonitrile copolymers prepared with 1 as initiator allows determination of the relative rates of addition of these olefins to the 1-cyanoethyl radical. We have found k A / k s = 0.12 f 0.03, a result conistent with the penultimate model treatment of this copolymerization system by Hill, O'Donnell, and O'Sullivan.