The electrospinning technique was used successfully to fabricate one-dimensional arrays of Au nanoparticles within nanofibers in which the intrinsic nature of the semicrystalline polymer poly(ethylene oxide) (PEO) was employed as a template for the controlled nanoscale organization of nanoparticles. Differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy, UV-visible spectroscopy, scanning electron microscopy, atomic force microscopy, and transmission electron microscopy (TEM) were performed to characterize the resulting electrospun fibers in comparison with pure PEO and PEO/Au nanocomposite before electrospinning. By choosing chloroform as the solvent in this work the observed electrospun fibers were about 400-650 nm in diameter and revealed a well-defined Gaussian distribution. Thermal analysis showed that the dodecanethiol-capped Au nanoparticles preferentially act as heterogeneous nucleating agents for PEO crystallization. Conformational changes occurred by incorporating Au nanoparticles as well as electrospinning. The most common helical structure of PEO was transformed into a trans zigzag planar structure due to the high extensional flow caused by electrospinning. As a striking result, fairly long and one-dimensional chainlike structures consisting of Au nanoparticles within the electrospun fibers were observed by TEM. The present findings demonstrate that the electrospinning process provides not only a fundamental understanding of the conformational changes upon process conditions, but also a straightforward and cost-effective technique to fabricate one-dimensional arrays of nanoparticles for future nanodevices with unique properties in various applications, such as biological sensors, single-electron transistors, photonic materials, etc.
13C-NMR MAS solid-state spectroscopy and 1H-NMR relaxation measurements have been applied for quantitative determination of crosslink density in sulfur-accelerated NR vulcanizates. It is shown that the 13C-NMR method is able to distinguish between monosulfidic crosslinks and polysulfldic structures; therefore a quantitative determination of chemical crosslinks was possible. An analysis of 13-NMR transversal relaxation measurements provided the network densities which were in good agreement with the results of the 13C-NMR measurements. Comparing stress-strain data with the spectroscopically determined crosslink density of the NR vulcanizates and calculated crosslink densities of peroxide-cured vulcanizates, it is shown that the same relation between low-strain modulus and crosslink density is valid independent of the structure of the vulcanizates. The chemical crosslink density determined by a theoretical approach based on the tube concept was in approximate agreement with the NMR results.
Low-pressure microwave plasma has been used to incorporate new functionalities onto the surface of cyclic olefin copolymers (COC). The main goal of the plasma treatment was to hydrophilize the COC's surface in order to enhance its adhesion to metals. The effect of two plasma parameters (treatment time and type of plasma gas) on the adhesion properties has been investigated. In order to investigate the opportunity for optimization of the adhesive strength in the COC-metal composite, an adhesion-promoting layer of acrylic acid (AA), or inorganic SiO 2 , has been deposited.
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