Island clusters: By using kinetic control, stable Agn clusters (n≤10) are synthesized in microemulsions. Nanoislands composed of the subnanosized clusters can be deposited onto a substrate (see picture). The clusters are characterized by a variety of methods, including scanning tunneling microscopy (STM), mass spectrometry, UV/Vis spectroscopy, and differential pulse voltammetry.
The most significant results concerning a chemical study to evaluate the degradability of polymeric components in four contemporary works of art, partially or completely realized in plastics, are presented and discussed in this paper. The procedure applied is mainly based on the use of Fourier transform IR and UV-vis spectroscopies and pyrolysis-gas chromatography/mass spectrometry, and consists of the following steps: (1) compositional analysis of the artworks, with particular attention to components which may have a negative effect on the overall ageing; (2) evaluation of the actual state of conservation; (3) investigation of the accelerated ageing of reference polymer samples; and (4) monitoring of the natural ageing of the artworks. On such a basis, the following could be concluded. Stage Evidence by Loris Cecchini is made of poly(ether urethane) elastomer which contains a high amount of phthalates. Their exudation gives a sticky appearance to the artwork and their removal during ageing is the main cause of the loss of flexibility. The latex used by Andrés Pinal for tailoring Traxe de Home is a natural polyisoprene, whose oxidative degradation accounts for the extensive deterioration and yellowing of the artwork. The plaster sculptures of 3D Bodyscans 1:9 by Karin Sander are coated with an aliphatic epoxy resin. Its oxidation with formation of amides is the cause of the surface yellowing. The adhesive used by Dario Villalba for Tierra, Ladrillo y Agua is a commercial poly(vinyl acetate). Simulated photoageing suggests a fast deterioration due to deacetylation and cross-linking, which possibly is the main reason for the actual detachment of debris from the support.
Cobalt nanoparticles (NPs) were synthesized via an electrochemical method in the presence of tetraalkylammonium salt. The nanometer dimensions of the NPs can be controlled in a simple way by adjustment of the current density. From these particles stable colloidal suspensions are prepared in the presence of a fatty acid (oleic acid) and triphenylphosphine. The colloidal system is stable against oxidation when they are kept in heptane (C 7 H 16 ).Transmission electron microscopy (TEM) was employed to determine the core size and the shape of metal nanoparticles. The chemical interaction of the surfactant with the Co nanoparticles was studied by using Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR). Thermogravimetric analysis (TGA) was used to study the thermal stability and the composition of the capped cobalt nanoparticles.
Thermal annealing was used for the bottom-up fabrication of morphologically controlled gold-block-copolymer (Au-BC) nanocomposites. Three different blends formed by polystyrene (PS) homopolymer and PS-coated gold nanoparticles (PSSH@Au) were used as modifiers of asymmetric polystyrene-b-polymethylmethacrylate (PS-b-PMMA): PS26/PS26SH@Au, PS75/PS75SH@Au and PS167/PS167SH@Au (where the subscripts refer to the number of styrene monomeric units).The results indicated that all three blends used as modifiers (PSn/PSnSH@Au) were successfully located in the PS phase during thermally induced BC self-assembly for a composition range from 5 to 43 wt% without macro-phase separation. The PSnSH@Au moiety experienced molecular desorption, nanocrystal core coalescence and partial molecular re-encapsulation processes during thermal annealing, leading to sphere-like gold NPs with a larger average size (without exceeding an interdomain distance). Ligand chain length regulated the degree of coalescence and re-encapsulation, defining ultimate core size. Furthermore, proper combination of chain length and composition enabled tuning of NP partitioning and arrangement on different length scales through thermally activated cooperative assembly processes. These results have not only significant impact for establishing thermal processing as a useful tool for the precise control of NP size and distribution, but also much broader implications for many nanoparticle-based technologies.
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