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Articles 1 - 8 of 8
Full-Text Articles in Materials Chemistry
Macroporous Silica Using A “Sticky” Stöber Process, Rebecca Cademartiri, Michael A. Brook, Robert Pelton, John D. Brennan
Macroporous Silica Using A “Sticky” Stöber Process, Rebecca Cademartiri, Michael A. Brook, Robert Pelton, John D. Brennan
Rebecca Cademartiri
The generation of macroporous silica structures using a sol–gel process generally requires the presence of high molecular weight, water-soluble polymers. We demonstrate that significantly lower molecular weight poly(ethylene glycol) (PEG) polymers can drive a particle aggregation process to generate macroporous silica. Compared to unfunctionalized PEGs (HO–PEG–HO, molecular weight > 10 000 g mol−1), PEG polymers with allyl (A–PEG–A) or silyl end groups (CH2)3Si(OEt)3 (Si–PEG–Si), with molecular weights of 2000 g mol−1 or greater, lead to monolithic macroporous structures derived from aggregates of nearly monodisperse particles. Lower molecular weight (less than 1000 g mol−1) allyl or silyl PEG, or hydroxy-terminated PEG–OH, lead …
Preparation Of Wo3 Nanoparticles Using Cetyl Trimethyl Ammonium Bromide Supermolecular Template, Nilofar Asim, S. Radiman, M.A. Bin Yarmo
Preparation Of Wo3 Nanoparticles Using Cetyl Trimethyl Ammonium Bromide Supermolecular Template, Nilofar Asim, S. Radiman, M.A. Bin Yarmo
Nilofar Asim
WO3 is one of the most interested metal oxides because of its application as catalysts, sensors, electrochromic devices, ceramic, solar cell, pigments and so on. More investigation is needed to find the good and low cost method for preparation of WO3 nanoparticles with uniform morphology and narrow distribution using a surfactant mediated method. Approach: In this study, the synthesis of WO3 nanoparticles was accomplished using a cationic surfactant (cetyl trimethyl ammonium bromide) as the organic supermolecular template and WCl6 and NH4 OH as the inorganic precursor and counter ion source, respectively. The effects of reaction temperature and surfactant concentration in …
Surface Investigation Of Chitosan Film With Fatty Acid Monolayers, M Misran
Surface Investigation Of Chitosan Film With Fatty Acid Monolayers, M Misran
Misni Misran
The surface pressure-molecular area (pi-A) isotherm curves of two fatty acids of different chain lengths, i.e. stearic (C(18)) and arachidic (C(20)) acids, were obtained by using Langmuir-Blodgett (LB) technique. Results showed clear isotherm plots with limiting mean molecular area around 21 angstrom(2) for both acids. However, the monolayer was found to collapse at higher than 33 mN m(-1) and 21 mN m(-1) for stearic acid and arachidic acid respectively. The effect of Langmuir-Blodgett monolayers of the acids was investigated by atomic force microscopy (AFM). Chitosan film, before and after dipping in water, was also studied by means of AFM so …
Rhodium Nanoparticle Shape Dependence In The Reduction Of No By Co, James Russell Renzas, Yawen Zhang, Wenyu Huang, Gabor Somoraji
Rhodium Nanoparticle Shape Dependence In The Reduction Of No By Co, James Russell Renzas, Yawen Zhang, Wenyu Huang, Gabor Somoraji
Wenyu Huang
The shape dependence of the catalytic reduction of nitric oxide by carbon monoxide on rhodium nanopoly- hedra and nanocubes was studied from 230 to 270 ° C. The nanocubes are found to exhibit higher turnover frequency and lower activation energy than the nanopolyhedra. These trends are compared to previous studies on Rh single crystals.
Sub-10 Nm Platinum Nanocrystals With Size And Shape Control: Catalytic Study For Ethylene And Pyrrole Hydrogenation, Chia-Kuang Tsung, John N. Kuhn, Wenyu Huang, Cesar Aliaga, Ling-I Hung, Gabor A. Somorjai, Peidong Yang
Sub-10 Nm Platinum Nanocrystals With Size And Shape Control: Catalytic Study For Ethylene And Pyrrole Hydrogenation, Chia-Kuang Tsung, John N. Kuhn, Wenyu Huang, Cesar Aliaga, Ling-I Hung, Gabor A. Somorjai, Peidong Yang
Wenyu Huang
Platinum nanocubes and nanopolyhedra with tunable size from 5 to 9 nm were synthesized by controlling the reducing rate of metal precursor ions in a one-pot polyol synthesis. A two-stage process is proposed for the simultaneous control of size and shape. In the first stage, the oxidation state of the metal ion precursors determined the nucleation rate and consequently the number of nuclei. The reaction temperature controlled the shape in the second stage by regulation of the growth kinetics. These well-defined nanocrystals were loaded into MCF-17 mesoporous silica for examination of catalytic properties. Pt loadings and dispersions of the supported …
Photoaffinity Labeling Via Nitrenium Ion Chemistry: Protonation Of The Nitrene Derived From 4-Amino-3-Nitrophenyl Azide To Afford Reactive Nitrenium Ion Pairs, Valentyna Voskresenska, R. Marshall Wilson, Maxim Panov, Alexander N. Tarnovsky, Jeanette A. Krause, Shubham Vyas, Arthur Winter, Christopher M. Hadad
Photoaffinity Labeling Via Nitrenium Ion Chemistry: Protonation Of The Nitrene Derived From 4-Amino-3-Nitrophenyl Azide To Afford Reactive Nitrenium Ion Pairs, Valentyna Voskresenska, R. Marshall Wilson, Maxim Panov, Alexander N. Tarnovsky, Jeanette A. Krause, Shubham Vyas, Arthur Winter, Christopher M. Hadad
Arthur Winter
Phenyl azides with powerful electron-donating substituents are known to deviate from the usual photochemical behavior of other phenyl azides. They do not undergo ring expansion but form basic nitrenes that protonate to form nitrenium ions. The photochemistry of the widely used photoaffinity labeling system 4-amino-3-nitrophenyl azide, 5, has been studied by transient absorption spectroscopy from femtosecond to microsecond time domains and from a theoretical perspective. The nitrene generation from azide 5 occurs on the S2 surface, in violation of Kasha’s rule. The resulting nitrene is a powerful base and abstracts protons extremely rapidly from a variety of sources to form …
Self-Organized Ultrathin Oxide Nanocrystals, Ziyang Huo, Chia-Kuang Tsung, Wenyu Huang, Melissa Fardy, Ruoxue Yan, Xiaofeng Zhang, Yandong Li, Peidong Yang
Self-Organized Ultrathin Oxide Nanocrystals, Ziyang Huo, Chia-Kuang Tsung, Wenyu Huang, Melissa Fardy, Ruoxue Yan, Xiaofeng Zhang, Yandong Li, Peidong Yang
Wenyu Huang
Sub-2-nm (down to one-unit cell) uniform oxide nanocrystals and highly ordered superstructures were obtained in one step using oleylamine and oleic acid as capping and structure directing agents. The cooperative nature of the nanocrystal growth and assembly resulted in mesoscopic one-dimensional ribbon-like superstructures made of these ultrathin nanocrystals. The process reported here is general and can be readily extended to the production of many other transition metal (TiO2, ZnO, Nb2O5) and rare earth oxide (Eu2O3, Sm2O3, Er2O3, Y2O3, Tb2O3, and Yb2O3) systems.
Highly Fluorous Complexes Of Ruthenium And Osmium And Their Solubility In Supercritical Carbon Dioxide, Brad Berven, George Koutsantonis, Brian Skelton, Robert Trengove, Allan White
Highly Fluorous Complexes Of Ruthenium And Osmium And Their Solubility In Supercritical Carbon Dioxide, Brad Berven, George Koutsantonis, Brian Skelton, Robert Trengove, Allan White
Brad Berven
A series of ruthenium and osmium complexes containing highly fluorous diphosphine ligands FPPF = (F13C6C6H4-p)2P(CH2)2P(p-C6H4C6F13)2 (dfppe) and (F13C6C6H4-p)2P(CH2)3P(p-C6H4C6F13)2 (dfppp) has been prepared. The fluorous diphosphine ligands incorporate four C6F13 “fluoro-ponytails”, and these have been effective in solubilizing the complexes in supercritical carbon dioxide (scCO2). Precise solubility measurements in scCO2 were performed for some of the complexes. The new complexes [MX2(FPPF)2] and [MX(FPPF)(η-C5H5)], M = Ru, Os, X = Cl, Br, have been characterized by a number of spectroscopic techniques and their electrochemical properties measured, three of the ruthenium complexes also being characterized by single-crystal X-ray studies. The noncovalent interactions observed …