TY - JOUR A1 - Goebel, Ronald A1 - Hesemann, Peter A1 - Weber, Jens A1 - Moeller, Eléonore A1 - Friedrich, Alwin A1 - Beuermann, Sabine A1 - Taubert, Andreas T1 - Surprisingly high, bulk liquid-like mobility of silica-confined ionic liquids N2 - Mesoporous silica monoliths were prepared by the sol - gel technique and. lled with 1-ethyl-3-methyl imidazolium [Emim]-X (X = dicyanamide [N(CN)(2)], ethyl sulfate [EtSO4], thiocyanate [SCN], and triflate [TfO]) ionic liquids (ILs) using a methanol-IL exchange technique. The structure and behavior of the ILs inside the silica monoliths were studied using X-ray scattering, nitrogen sorption, IR spectroscopy, solid-state NMR, and thermal analysis. DSC finds shifts in both the glass transition temperature and melting points (where applicable) of the ILs. Glass transition and melting occur well below room temperature. There is thus no conflict with the NMR and IR data, which show that the ILs are as mobile at room temperature as the bulk (not confined) ILs. The very narrow line widths of the NMR spectra suggest that the ILs in our materials have the highest mobility reported for confined ILs so far. As a result, our data suggest that it is possible to generate IL/silica hybrid materials (ionogels) with bulk-like properties of the IL. This could be interesting for applications in, e.g., the solar cell or membrane fields. Y1 - 2009 UR - http://xlink.rsc.org/jumptojournal.cfm?journal_code=CP U6 - https://doi.org/10.1039/B821833a SN - 1463-9076 ER - TY - JOUR A1 - Graf, Philipp A1 - Mantion, Alexandre A1 - Foelske, Annette A1 - Shkilnyy, Andriy A1 - MaÜic, Admir A1 - Thuenemann, Andreas F. A1 - Taubert, Andreas T1 - Peptide-coated silver nanoparticles : synthesis, surface chemistry, and pH-triggered, reversible assembly into particle assemblies N2 - Simple tripeptides are scaffolds for the synthesis and further assembly of peptide/silver nanoparticle composites. Herein, we further explore peptide-con trolled silver nanoparticle assembly processes. Silver nanoparticles with a pH-responsive peptide coating have been synthesized by using a one-step precipitation/coating route. The nature of the peptide/silver interaction and the effect of the peptide oil the formation of the silver particles have been studied via UV/Vis, X-ray photoelectron, and surface-enhanced Raman spectroscopies as well as through electron microscopy, small angle X-ray scattering and powder Xray diffraction with Rietveld refinement. The particles reversibly form aggregates of different sizes in aqueous solution. The state of aggregation call be controlled by the solution pH value. At low pH values, individual particles are present. At neutral pH values, small clusters form and at high pH values, large precipitates are observed. Y1 - 2009 UR - http://www3.interscience.wiley.com/cgi-bin/jhome/26293/ U6 - https://doi.org/10.1002/chem.200802329 SN - 0947-6539 ER - TY - JOUR A1 - Kind, Lucy A1 - Plamper, Felix A. A1 - Goebel, Ronald A1 - Mantion, Alexandre A1 - Mueller, Axel H. E. A1 - Pieles, Uwe A1 - Taubert, Andreas A1 - Meier, Wolfgang P. T1 - Silsesquioxane/polyamine nanoparticle-templated formation of star- or raspberry-like silica nanoparticles N2 - Silica is an important mineral in biology and technology, and many protocols have been developed for the synthesis of complex silica architectures. The current report shows that silsesquioxane nanoparticles carrying polymer arms on their surface are efficient templates for the fabrication of silica particles with a star- or raspberry-like morphology. The shape of the resulting particles depends on the chemistry of the polymer arms. With poly(N,N- dimethylaminoethyl methacrylate) (PDMAEMA) arms, spherical particles with a less electron dense core form. With poly {[2- (methacryloyloxy)ethyl] trimethylammonium iodide} (PMETAI), star- or raspberry-like particles form. Electron microscopy, electron tomography, and small-angle X-ray scattering show that the resulting silica particles have a complex structure, where a silsequioxane nanoparticle carrying the polymer arms is in the center. Next is a region that is polymer-rich. The outermost region of the particle is a silica layer, where the outer parts of the polymer arms are embedded. Time- resolved zeta-potential and pH measurements, dynamic light scattering, and electron microscopy reveal that silica formation proceeds differently if PDMAEMA is exchanged for PMETAI. Y1 - 2009 UR - http://pubs.acs.org/journal/langd5 U6 - https://doi.org/10.1021/La900229n SN - 0743-7463 ER - TY - GEN A1 - Li, Zhonghao A1 - Taubert, Andreas T1 - Cellulose/gold nanocrystal hybrids via an ionic liquid/aqueous precipitation route N2 - Injection of a mixture of HAuCl4 and cellulose dissolved in the ionic liquid (IL) 1-butyl-3-methylimidazolium chloride [Bmim]Cl into aqueous NaBH4 leads to colloidal gold nanoparticle/cellulose hybrid precipitates. This process is a model example for a very simple and generic approach towards (noble) metal/cellulose hybrids, which could find applications in sensing, sterile filtration, or as biomaterials. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 135 KW - Cellulose KW - Gold nanoparticles KW - Ionic liquid KW - Precipitation KW - Hybrid material Y1 - 2009 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-45046 ER - TY - JOUR A1 - Navarro, Salvador A1 - Shkilnyy, Andriy A1 - Tiersch, Brigitte A1 - Taubert, Andreas A1 - Menzel, Henning T1 - Preparation, characterization, and thermal gelation of amphiphilic alkyl-poly(ethyleneimine) N2 - Amphiphilic alkyl-poly(ethyleneimine)s (alkyl-PEI) with different degrees of polymerization have been produced by alkaline hydrolysis of alkyl-poly(2-methyl-2-oxazoline). Potentiometric titration of the alkyl-PEI shows the influence of the alkyl chain and the degree of polymerization on the titration curves and hence on the polymer conformation. Karl Fischer titration has been used to determine the water content in the polymers. Subsequent X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and differential scanning calorimetry (DSC) measurements prove the existence of different hydration states of the PEI even under dry storage conditions. Upon cooling from hot aqueous Solutions, hydrogels form. The gelation concentration decreases with increasing degree of polymerization of the PEI segment. Scanning electron microscopy (SEM and cryo-SEM) of the hydrogels reveal an alkyl-PEI fibrous network composed of fan-like units. DSC shows that the percentages of bound and free water in the hydrogels depend on the concentration of polar amino groups. Y1 - 2009 UR - http://pubs.acs.org/journal/langd5 U6 - https://doi.org/10.1021/La9013569 SN - 0743-7463 ER - TY - JOUR A1 - Shkilnyy, Andriy A1 - Brandt, Jessica A1 - Mantion, Alexandre A1 - Paris, Oskar A1 - Schlaad, Helmut A1 - Taubert, Andreas T1 - Calcium phosphate with a channel-like morphology by polymer templating N2 - Calcium phosphate mineralization from aqueous solution in the presence of organic growth modifiers has been intensely studied in the recent past. This is mostly due to potential applications of the resulting composites in the biomaterials field. Polymers in particular are efficient growth modifiers. As a result, there has been a large amount of work on polymeric growth modifiers. Interestingly, however, relatively little work has been done on polycationic additives. The current paper shows that poly(ethylene oxide)b-poly(L-lysine) block copolymers lead to an interesting morphology of calcium phosphate precipitated at room temperature and subjected to a mild heat treatment at 85 degrees C. Electron microscopy, synchrotron X-ray diffraction, and porosity analysis show that a (somewhat) porous material with channel-like features forms. Closer inspection using transmission electron microscopy shows that the channels are probably not real channels. Much rather the morphology is the result of the aggregation of ca. 100-nm-sized rodlike primary particles, which changes upon drying to exhibit the observed channel-like features. Comparison experiments conducted in the absence of polymer and with poly(ethylene oxide)-b-poly(L-glutamate) show that these features only form in the presence of the polycationic poly(L-lysine) block, suggesting a distinct interaction of the polycation with either the crystal or the phosphate ions prior to mineralization. Y1 - 2009 UR - http://pubs.acs.org/journal/cmatex U6 - https://doi.org/10.1021/Cm803244z SN - 0897-4756 ER - TY - JOUR A1 - Shkilnyy, Andriy A1 - Gräf, Ralph A1 - Hiebl, Bernhard A1 - Neffe, Axel T. A1 - Friedrich, Alwin A1 - Hartmann, Juergen A1 - Taubert, Andreas T1 - Unprecedented, low cytotoxicity of spongelike calcium phosphate/poly(ethylene imine) hydrogel composites N2 - Covalently crosslinked PEI hydrogels are efficient templates for calcium phosphate mineralization in SBF. In contrast to the PEI hydrogels, non-crosslinked PEI does not lead to calcium phosphate nucleation and growth in SBF. The precipitate is a mixture of brushite and hydroxyapatite. The PEI/calcium phosphate composite material exhibits a sponge like morphology and a chemical composition that is interesting for implants. Cytotoxicity tests using Dictyostelium discoideum amoebae show that both the non-mineralized and mineralized hydrogels have a very low cytotoxicity. This suggests that next generation PEI hydrogels, where also the degradation products are non-toxic, could be interesting for biomedical applications. Y1 - 2009 UR - http://www3.interscience.wiley.com/cgi-bin/jhome/77002860 U6 - https://doi.org/10.1002/mabi.200800266 SN - 1616-5187 ER -