Electroconductive fibers composed of cellulose and carbon nanotubes (CNTs) were spun using aqueous alkaline/urea solution. The microstructure and physical properties of the resulting fibers were investigated by scanning electron microscopy, Raman microscopy, wide-angle X-ray diffraction, tensile tests, and electrical resistance measurements. We found that these flexible composite fibers have sufficient mechanical properties and good electrical conductivity, with volume resistivities in the range of about 230-1 Ohm cm for 2-8 wt % CNT loading. The multifunctional sensing behavior of these fibers to tensile strain, temperature, environmental humidity, and liquid water was investigated comprehensively. The results show that these novel CNT/cellulose composite fibers have impressive multifunctional sensing abilities and are promising to be used as wearable electronics and for the design of various smart materials.
We have synthesized nanostructured metal/organic networks by cross-linking preformed aluminum-organic-stabilized Pt nanoparticles in solution with organic spacer molecules. The protonolytic cross-linking mechanism presented makes use of reactive aluminum methyl groups at the surface of the particles. The particles and their networks have been characterized by electron microscopy and IR spectroscopy. For the structural characterization of the hybrids, anomalous small-angle X-ray scattering (ASAXS) was applied.
Anomalous small-angle X-ray scattering (ASAXS) experiments with synchrotron radiation were performed to study the three-dimensional nanostructures of metal/organic hybrids formed by crosslinking aluminium-organic-stabilized platinum nanoparticles with various bifunctional organic spacer molecules. The advantage of ASAXS is the possibility of separating the particle scattering from that of the organic components, thus providing unbiased information about particle size distributions and interparticle correlation. In order to obtain the structural information from the scattering data, a model function based on Vrij's analytical solution for a multicomponent system of hard spheres is proposed. The model is applied to three different samples and the results are compared with those obtained from the application of Fourier methods (characteristic function) and X-ray absorption measurements.
We study the structure and reorientation dynamics of nanometer-sized water droplets inside nonionic reverse micelles (water/Igepal-CO-520/cyclohexane) with time-resolved mid-infrared pumpprobe spectroscopy and small angle x-ray scattering. In the time-resolved experiments, we probe the vibrational and orientational dynamics of the O-D bonds of dilute HDO:H 2 O mixtures in Igepal reverse micelles as a function of temperature and micelle size. We find that even small micelles contain a large fraction of water that reorients at the same rate as water in the bulk, which indicates that the polyethylene oxide chains of the surfactant do not penetrate into the water volume. We also observe that the confinement affects the reorientation dynamics of only the first hydration layer. From the temperature dependent surfacewater dynamics, we estimate an activation enthalpy for reorientation of 45 ± 9 kJ mol −1 (11 ± 2 kcal mol −1 ), which is close to the activation energy of the reorientation of water molecules in ice.
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