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Electrostatic Self-assembly (electrostatic + self-assembly)
Selected AbstractsElectrostatic Self-Assembly of a Pt-around-Au Nanocomposite with High Activity towards Formic Acid Oxidation,ANGEWANDTE CHEMIE, Issue 12 2010Sheng Zhang Gegensätze ziehen sich an: ,Pt-auf-Au"-Nanokomposite entstehen durch elektrostatische Selbstorganisation (siehe Bild; PDDA=Poly(diallyldimethylammoniumchlorid)) und sind in der Oxidation von Ameisensäure viel aktiver als reine Pt-Katalysatoren. Ein möglicher Grund hierfür ist der effiziente HCOO-Übertritt vom Au- auf die umgebenden Pt-Nanopartikel, wo HCOO zu CO2 weiteroxidiert wird. [source] Switchable Nanoassemblies from Macroions and Multivalent Dye CounterionsCHEMISTRY - A EUROPEAN JOURNAL, Issue 30 2008Immanuel Willerich Switching aggregation on and off: Electrostatic self-assembly in aqueous solution allows formation of supramolecular structures that can be switched "on" and "off" by pH. Thereby a reversible change between 5,nm building blocks and 150,nm assemblies occurs, while the color of the solution switches between red and yellow (see figure). The system presented consists of dendrimer macroions connected by multivalent dye counterions. [source] Chemical Bonding Assembly of Multifunctional Oxide NanocompositesADVANCED FUNCTIONAL MATERIALS, Issue 2 2010Gary Evans Abstract The synthesis, functionalization and assembly of metal oxide nanoparticles BaTiO3 and CoFe2O4 is presented. The ferroelectric (BaTiO3) and ferromagnetic (CoFe2O4) oxide nanoparticle surfaces are directly functionalized via the anchoring of phosphonic acid and aminosilane molecules that engender the nanoparticles with terminal carboxylic acid and amine functional groups, respectively. These promote the electrostatic self-assembly of the particles in non-polar solvents and permit the synthesis of more chemically robust assemblies linked by the covalent amide bond via the addition of the chemical coupling agent N - N, -dicyclohexylcarbodiimide. This functionalization and assembly procedure is applied to two systems: the first comprised of 50,nm BaTiO3 and 10,nm CoFe2O4 particles and the second of 200,nm BaTiO3 and 12.5,nm CoFe2O4 particles. The latter composites possess magnetoelectric properties when processed into dense ceramics and, as a direct result of the assembly performed in solution, have a high degree of homogeneity between the ferroelectric and ferromagnetic phases. The developed functionalization and assembly procedure is considered to be adaptable to the preparation of other hybrid oxide nanomaterials with different property combinations. [source] Photoluminescence Quenching Control in Quantum Dot,Carbon Nanotube Composite Colloids Using a Silica-Shell Spacer,ADVANCED MATERIALS, Issue 4 2006M. Grzelczak One-dimensional nanocomposite colloids are prepared by means of electrostatic self-assembly of CdTe nanocrystals on both carbon nanotubes (CNTs) and silica-coated CNTs (see Figure). The dense coverage of these linear nanoparticle assemblies minimizes the spacing between the nanocrystals, thereby facilitating efficient electronic and energy transfer along the nanotubes. [source] Topological polymer chemistry by electrostatic self-assemblyJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 19 2003Yasuyuki Tezuka Abstract Recent developments in topological polymer chemistry are outlined. First, nonlinear polymer topologies are systematically classified on the basis of topological considerations of constitutional isomerism in a series of alkanes (CnH2n+2), monocycloalkanes (CnH2n), and polycycloalkanes (CnH2n,2, CnH2n,4, etc.). Various pairs of topological isomers are identified in randomly coiled, flexible polymer molecules with cyclic and branched structures. An electro- static self-assembly and covalent fixation strategy has subsequently been developed for the efficient synthesis of a variety of topologically unique polymers, including monocyclic and polycyclic polymers, topological isomers, and topological block copolymers. In this process, new telechelics with moderately strained cyclic onium salt groups carrying multifunctional carboxylate counteranions have been designed as key polymeric precursors. Further extensions of topological polymer chem- istry have been achieved by the use of cyclic telechelics (kyklo -telechelics) and cyclic macromonomers, obtainable also by means of the electrostatic self-assembly and covalent fixation process. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2905,2917, 2003 [source] Chiral Induction, Memory, and Amplification in Porphyrin Homoaggregates Based on Electrostatic InteractionsCHEMPHYSCHEM, Issue 6 2009LiXi Zeng Dr. Abstract Supramolecular chirality in two configurational homoaggregates of anionic meso -tetrakis(4-sulfonatophenyl)porphyrin (TPPS) can be induced by D - and L -alanine in acidic water (see picture). The chirality can be further memorized and enforced through strong electrostatic interactions between TPPS aggregates and achiral poly(allylamine) [PAA]. Supramolecular chirality in two configurational homoaggregates of anionic meso -tetrakis(4-sulfonatophenyl)porphyrin (TPPS) can be induced by D - and L -alanine (Ala) in acidic water, respectively. The induced supramolecular chirality can be further memorized and enforced, even after complete removal of Ala or in the presence of excess Ala with the opposite configuration, through strong electrostatic interactions with achiral poly(allylamine) [PAA]. The ionic chiral interactions between TPPS and Ala or PAA are characterized by means of UV/Vis absorption and circular dichroism spectrometry. Fluorescence spectroscopy and atomic force microscopy are used as complementary techniques. On the basis of the comprehensive experimental results, a possible mechanism for chiral induction, memory, and amplification of TPPS homoaggregates by chiral amino acids and achiral PAA is proposed. Thus, we demonstrate a novel strategy to realize chiral memory in supramolecular systems by polyelectrolytes through hierarchical electrostatic self-assembly. [source] | |||||||||||||