TY - JOUR A1 - Adelsberger, Joseph A1 - Kulkarni, Amit A1 - Jain, Abhinav A1 - Wang, Weinan A1 - Bivigou Koumba, Achille Mayelle A1 - Busch, Peter A1 - Pipich, Vitaliy A1 - Holderer, Olaf A1 - Hellweg, Thomas A1 - Laschewsky, André A1 - Müller-Buschbaum, Peter A1 - Papadakis, Christine M. T1 - Thermoresponsive PS-b-PNIPAM-b-PS micelles : aggregation behavior, segmental dynamics, and thermal response N2 - We have studied I lie thermal behavior of amphiphilic, symmetric triblock copolymers having short, deuterated polystyrene (PS) end blocks and a large poly(N-isopropylacrylarnicle) (PNIPAM) middle block exhibiting a lower critical solution temperature (LCST) in aqueous solution. A wide range of concentrations (0.1-300 mg/mL) is investigated using it number of analytical methods such as fluorescence correlation spectroscopy (FCS), turbidimetry, dynamic light scattering (DLS), small-angle neutron scattering (SANS), and neutron spin-echo spectroscopy (NSE). The critical micelle concentration is determined using FCS to be 1 mu M or less. The collapse of the micelles at the LCST is investigated using turbidimetry and DLS and shows a weak dependence on the degree of polymerization of the PNIPAM block. SANS with contrast matching allows its to reveal the core-shell Structure of the micelles as well as their correlation as a function of temperature. The segmental dynamics of the PNIPAM shell are studied as a function of temperature and arc found to be faster in the collapsed state than in the swollen state. The mode detected has a linear dispersion in q(2) and is found to be faster in the collapsed state as compared to the swollen state. We attribute this result to the averaging over mobile and immobilized segments. Y1 - 2010 UR - http://pubs.acs.org/journal/mamobx U6 - https://doi.org/10.1021/Ma902714p SN - 0024-9297 ER - TY - JOUR A1 - Awad, Duha Jawad A1 - Conrad, Franziska A1 - Koch, Andreas A1 - Friedrich, Alwin A1 - Poeppl, Andreas A1 - Strauch, Peter T1 - 2,2'-Bipyridin-1,2-dithiolat Gemischtligand-Komplexe : Systhese, Charakterisierung und EPR-Spektroskopie N2 - A series of new 2 2'-bipyridine/1 2-dithiolate transition metal complexes has been synthesised and characterised As 1,2-dithiolate ligands 1,2 dithiooxalate (dto) and 1 2-dithiosquarate (dtsq) were used It follows from the IR spectra that the multidentate dithiolate ligands coordinate exclusively via their sulfur atoms forming an MN2S2 coordination sphere The central metal ions (M) are Cu2+ Ni2+ Pd2+ Pt2+, and Zn2+ The complex [Cu-II(bpy)(dto)] could be studied by EPR spectroscopy and was measured as powder diamagnetically diluted in the isostructural [Ni-II(bpy)(dto)] host structure The spin density contribution calculated from the experimental parameters is compared with the electronic situation in the frontier orbitals namely in the semi occupied SOMO of the copper complex derived from quantum chemical calculations on different levels (EHT and DFT) Y1 - 2010 UR - http://www.znaturforsch.com/b.htm SN - 0932-0776 ER - TY - JOUR A1 - Awad, Duha Jawad A1 - Conrad, Franziska A1 - Koch, Andreas A1 - Schilde, Uwe A1 - Poeppl, Andreas A1 - Strauch, Peter T1 - 1,10-phenanthroline-dithiolate mixed ligand transition metal complexes : synthesis, characterization and EPR spectroscopy N2 - A series of new N2S2 mixed ligand transition metal complexes, where N-2 is phenanthroline and S-2 is 1,2- dithiooxalate (dto) or 1,2-dithiosquarate (dtsq), has been synthesized and characterized. IR spectra reveal that the 1,2- dithiolate ligands are coordinated via the sulfur atoms forming a N2S2 coordination sphere. The copper(II) complex [Cu(phen)(dto)] was studied by EPR spectroscopy as a diamagnetically diluted powder. The diamagnetic dilution resulted from doping of the copper complex into the isostructural host lattice of the nickel complex [Ni(phen)(dto)]. The electronic situation in the frontier orbitals of the copper complex calculated from the experimental data is compared to the results of EHT and DFT calculations. Furthermore, one side product, chlorobis(1,10-phenanthroline)copper(I) ethanol solvate hydrate [(phen)(2)CuCl]center dot C2H5OH center dot H2O, was formed by a reduction process and characterized by X-ray diffraction. In the crystal packing one-dimensional columns of dimers are formed, stabilized by significant pi-pi interactions. Y1 - 2010 UR - http://www.sciencedirect.com/science/journal/00201693 U6 - https://doi.org/10.1016/j.ica.2010.01.021 SN - 0020-1693 ER - TY - JOUR A1 - Ayi, Ayi A. A1 - Khare, Varsha A1 - Strauch, Peter A1 - Girard, Jèrôme A1 - Fromm, Katharina M. A1 - Taubert, Andreas T1 - On the chemical synthesis of titanium nanoparticles from ionic liquids N2 - We report on attempts towards the synthesis of titanium nanoparticles using a wet chemical approach in imidazolium-based ionic liquids (ILs) under reducing conditions. Transmission electron microscopy finds nanoparticles in all cases. UV/Vis spectroscopy confirms the nanoparticulate nature of the precipitate, as in all cases an absorption band between ca. 280 and 300 nm is visible. IR spectroscopy shows that even after extensive washing and drying, some IL remains adsorbed on the nanoparticles. Raman spectroscopy suggests the formation of anatase nanoparticles, but X-ray diffraction reveals that, possibly, amorphous titania forms or that the nanoparticles are so small that a clear structure assignment is not possible. The report thus shows that (possibly amorphous) titanium oxides even form under reducing conditions and that the chemical synthesis of titanium nanoparticles in ILs remains elusive. Y1 - 2010 UR - http://www.springerlink.com/content/101572 U6 - https://doi.org/10.1007/s00706-010-0403-4 SN - 0026-9247 ER - TY - THES A1 - Bai, Shuo T1 - Active hydrogels with nanocomposites Y1 - 2010 CY - Potsdam ER - TY - JOUR A1 - Baranac-Stojanovic, Marija A1 - Klaumuenzer, Ute A1 - Markovic, Rade A1 - Kleinpeter, Erich T1 - Structure, configuration, conformation and quantification of the push pull-effect of 2-alkylidene-4- thiazolidinones and 2-alkylidene-4,5-fused bicyclic thiazolidine derivatives N2 - Structures of a series of push-pull 2-alkylidene-4-thiazolidinones and 2-alkylidene-4,5-fused bicyclic thiazolidine derivatives were optimized at the B3LYP/6-31G(d) level of theory in the gas phase and discussed with respect to configurational and conformational stability. Employing the GIAO method, C-13 NMR chemical shifts of the C-2, C-2', C-4 and C-5 atoms were calculated at the same level of theory in the gas phase and with inclusion of solvent, and compared with experimental data. Push-pull effect of all compounds was quantified by means of the quotient pi*/pi, length of the partial double bond, C-13 NMR chemical shift difference (Delta delta(C=C)) and H-1 NMR chemical shifts of olefinic protons. The effect of bromine on donating and accepting ability of other substituents of the push- pull C=C double bond is discussed, too. Y1 - 2010 UR - http://www.sciencedirect.com/science/journal/00404020 U6 - https://doi.org/10.1016/j.tet.2010.09.040 SN - 0040-4020 ER - TY - THES A1 - Belova, Valentina T1 - Composite fabrication and surface modification via high intensity ultrasound Y1 - 2010 CY - Potsdam ER - TY - JOUR A1 - Biermann, Ursula A1 - Metzger, Juergen O. A1 - Meier, Michael A. R. T1 - Acyclic triene metathesis oligo- and polymerization of high oleic sun flower oil N2 - High oleic sunflower oil, a renewable raw material consisting of triglycerides with internal C=C-double bonds, was polymerized via acyclic triene metathesis (ATMET) to highly branched and functionalized polyesters. If the Hoveyda- Grubbs second generation catalyst was used and methyl acrylate was introduced as a chain stopper, the molecular weight of the obtained polymers could be tuned by varying the ratio of the triglyceride and methyl acrylate. Using the first generation Grubbs catalyst for the polymerization of high oleic sunflower oil, no cross-linking was observed, even without the use of a chain stopper. The resulting branched materials were characterized by GPC, H-1 and C-13 NMR, and ESI-MS. Y1 - 2010 UR - http://www3.interscience.wiley.com/journal/10003495/home U6 - https://doi.org/10.1002/macp.200900615 SN - 1022-1352 ER - TY - JOUR A1 - Bivigou Koumba, Achille Mayelle A1 - Goernitz, Eckhard A1 - Laschewsky, André A1 - Müller-Buschbaum, Peter A1 - Papadakis, Christine M. T1 - Thermoresponsive amphiphilic symmetrical triblock copolymers with a hydrophilic middle block made of poly(N- isopropylacrylamide) : synthesis, self-organization, and hydrogel formation N2 - Several series of symmetrical triblock copolymers were synthesized by the reversible addition fragmentation chain transfer method. They consist of a long block of poly(N-isopropylacrylamide) as hydrophilic, thermoresponsive middle block, which is end-capped by two small strongly hydrophobic blocks made from five different vinyl polymers. The association of the amphiphilic polymers was studied in dilute and concentrated aqueous solution. The polymer micelles found at low concentrations form hydrogels at high concentrations, typically above 30-35 wt.%. Hydrogel formation and the thermosensitive rheological behavior were studied exemplarily for copolymers with hydrophobic blocks of polystyrene, poly(2-ethylhexyl acrylate), and poly(n-octadecyl acrylate). All systems exhibited a cloud point around 30 A degrees C. Heating beyond the cloud point initially favors hydrogel formation but continued heating results in macroscopic phase separation. The rheological behavior suggests that the copolymers associate into flower-like micelles, with only a small share of polymers that bridge the micelles and act as physical cross-linkers, even at high concentrations. Y1 - 2010 UR - http://www.springerlink.com/content/101551 U6 - https://doi.org/10.1007/s00396-009-2179-9 SN - 0303-402X ER - TY - JOUR A1 - Borchert, Manuela A1 - Wilke, Max A1 - Schmidt, Christian A1 - Rickers, Karen T1 - Rb and Sr partitioning between haplogranitic melts and aqueous solutions N2 - Rubidium and strontium partitioning experiments between haplogranitic melts and aqueous fluids (water or 1.16- 3.56 m (NaCl + KCl) +/- HCl) were conducted at 750-950 degrees C and 0.2-1.4 GPa to investigate the effects of melt and fluid composition, pressure, and temperature. In addition, we studied if the applied technique (rapid and slow quench, and in-situ determination of trace element concentration in the fluid) has a bearing on the obtained data. There is good agreement of the data from different techniques for chloridic solutions, whereas back reactions between fluid and Melt upon cooling have a significant effect on results from the experiments with water. The Rb fluid-melt partition coefficient shows no recognizable dependence on melt composition and temperature. For chloridic Solutions, it is similar to 0.4, independent of pressure. In experiments with water, it is one to two orders of magnitude lower and increases with pressure. The strontium fluid-melt partition coefficient does not depend on temperature. It increases slightly with pressure in Cl free experiments. In chloridic fluids, there is a sharp increase in the Sr partition coefficient with the alumina saturation index (ASI) from 0.003 at an ASI of 0.8 to a maximum of 0.3 at an ASI of 1.05. At higher ASI, it decreases slightly to 0.2 at an ASI of 1.6. It is one to two orders of magnitude higher in chloridic fluids compared to those found in H2O experiments. The Rb/Sr ratio in non-chloridic solutions in equilibrium with metaluminous melts increases with pressure, whereas the Rb/Sr ratio in chloridic fluids is independent of pressure and decreases with fluid salinity. The obtained fluid-melt partition coefficients are in good agreement with data from natural cogenetic fluid and melt inclusions. Numerical modeling shows that although the Rb/Sr ratio in the residual melt is particularly sensitive to the degree of fractional crystallization, exsolution of a fluid phase, and associated fluid-melt partitioning is not a significant factor controlling Rb and Sr concentrations in the residual melt during crystallization of most granitoids. Y1 - 2010 UR - http://www.sciencedirect.com/science/journal/00167037 U6 - https://doi.org/10.1016/j.gca.2009.10.033 SN - 0016-7037 ER -