The Experts below are selected from a list of 276 Experts worldwide ranked by ideXlab platform
Moonhyun Oh - One of the best experts on this subject based on the ideXlab platform.
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advanced fabrication of metal organic frameworks template directed formation of Polystyrene zif 8 core shell and hollow zif 8 microspheres
Chemical Communications, 2012Co-Authors: Moonhyun OhAbstract:The conjunction of porous ZIF-8 with Polystyrene spheres is demonstrated to induce the formation of Polystyrene@ZIF-8 core–shell structures. A subsequent etching process on Polystyrene@ZIF-8 core–shells to remove Polystyrene cores results in a unique hollow ZIF-8.
A. Ueno - One of the best experts on this subject based on the ideXlab platform.
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Catalytic degradation of Polystyrene into styrene and a design of recyclable Polystyrene with dispersed catalysts
Catalysis Today, 2000Co-Authors: H. Ukei, M. Taka, N. Azuma, Sanae Horikawa, Y. Takai, T. Hirose, A. UenoAbstract:Degradation of Polystyrene into styrene, including monomer and dimer, was studied using various kinds of solid acids and bases as catalysts. It was found that solid bases were more effective catalysts than solid acids for the degradation of Polystyrene into styrene. This was attributed to differences in the degradation mechanisms of Polystyrene over solid acids and bases. Among the solid bases employed, BaO was found to be the most effective catalyst, and about 90 wt.% of Polystyrene was converted into styrene when thermally degraded Polystyrene was admitted to BaO powder at 623 K. Polystyrene films with dispersed BaO powder were then prepared as a model of a recyclable plastic using a twin-roller heated at 393 K; the amount of BaO dispersed was only 1 wt.% of the Polystyrene films. More than 85 wt.% of the Polystyrene films with dispersed BaO were converted into styrene by simple thermal degradation at 623 K without assistance of other catalytic compounds. The films were expanded into Polystyrene foams with dispersed BaO using a gas absorption/evolution technique. Styrene could be recovered from these foams by heating them at 673 K.
Yusuf Yagci - One of the best experts on this subject based on the ideXlab platform.
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Synthesis and characterization of pyrrole and thiophene functional Polystyrenes via “click chemistry”
Polymer Bulletin, 2011Co-Authors: Baris Kiskan, Burcin Gacal, Mirnur Asan, Emre Comert Gunaydin, Ismail Yilmaz, Yusuf YagciAbstract:Novel side-chain pyrrole or thiophene functional Polystyrenes (PS-Py and PS-Th) were synthesized by using ‘‘click chemistry’’ strategy. First, approximately 40% of chloro groups of poly(styrene- co -chloromethylstyrene) P(S- co -CMS), prepared by nitroxide mediated radical polymerization (NMRP), were converted to azido groups by using NaN_3 in N , N -dimethylformamide. Propargyl pyrrole was prepared by etherification of 4-(1 H -pyrrol-1-yl)phenol prepared by Clauson-Kaas reaction using propargylbromide. Propargyl thiophene was synthesized by heterogeneous esterification reaction between 3-thiophenecarboxylic acid and propargylbromide. Finally, azido-functionalized Polystyrene was coupled to these propargyl functional heterocyclics with high efficiency by click chemistry. The intermediates at various stages and final polymers were characterized by spectral analysis and cyclic voltammetry.
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Synthesis and characteristics of polymacromonomers composed of alternating binaphthalene-phenylene main chain and Polystyrene side chains
Polymer, 2007Co-Authors: Ioan Cianga, V. M. Mercore, Mircea Grigoras, Yusuf YagciAbstract:Well-defined Polystyrene (PSt) based polymers containing middle- or end-chain 2,5- or 3,5-dibromobenzene moieties, prepared by Atom Transfer Radical Polymerization (ATRP) were implied in Suzuki type couplings with 1-naphthalene boronic acid. The resulting polymers, containing a conjugated sequence with 1-naphthyl groups at the extremities, were used as macromonomers in chemical oxidative polymerization in the presence of anhydrous FeCl3. Polyarylenes, with a hairy-rod structure, having binaphthyl groups in the main chain and the respective PSt chains as lateral substituents, were obtained. All the starting, intermediate or final polymers were structurally analyzed by spectral methods (1H NMR, IR) and GPC measurements. Thermal behavior of the macromonomers and final polymers was investigated by Differential Scanning Calorimetry (DSC) analyses. Optical properties of the polymers were followed by UV and fluorescence spectroscopies. The absorption spectra of the polymers indicate only a limited extend of conjugation as compared to the naphthalene functionalized Polystyrenes. However, in the emission spectra of the polymers, a bathochromic shift with respect to the monomers was observed in all cases. © 2007 Elsevier Ltd. All rights reserved.
H. Ukei - One of the best experts on this subject based on the ideXlab platform.
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Catalytic degradation of Polystyrene into styrene and a design of recyclable Polystyrene with dispersed catalysts
Catalysis Today, 2000Co-Authors: H. Ukei, M. Taka, N. Azuma, Sanae Horikawa, Y. Takai, T. Hirose, A. UenoAbstract:Degradation of Polystyrene into styrene, including monomer and dimer, was studied using various kinds of solid acids and bases as catalysts. It was found that solid bases were more effective catalysts than solid acids for the degradation of Polystyrene into styrene. This was attributed to differences in the degradation mechanisms of Polystyrene over solid acids and bases. Among the solid bases employed, BaO was found to be the most effective catalyst, and about 90 wt.% of Polystyrene was converted into styrene when thermally degraded Polystyrene was admitted to BaO powder at 623 K. Polystyrene films with dispersed BaO powder were then prepared as a model of a recyclable plastic using a twin-roller heated at 393 K; the amount of BaO dispersed was only 1 wt.% of the Polystyrene films. More than 85 wt.% of the Polystyrene films with dispersed BaO were converted into styrene by simple thermal degradation at 623 K without assistance of other catalytic compounds. The films were expanded into Polystyrene foams with dispersed BaO using a gas absorption/evolution technique. Styrene could be recovered from these foams by heating them at 673 K.
Ludger Harnau - One of the best experts on this subject based on the ideXlab platform.
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a fluorescence correlation spectroscopy study of macromolecular tracer diffusion in polymer solutions
Journal of Physics: Condensed Matter, 2010Co-Authors: Ute Zettl, Matthias Ballauff, Ludger HarnauAbstract:We discuss the manner in which the dynamics of tracer Polystyrene chains varies with the concentration of matrix Polystyrene chains dissolved in toluene. Using fluorescence correlation spectroscopy and theory, it is shown that the cooperative diffusion coefficient of the matrix Polystyrene chains can be measured by fluorescence correlation spectroscopy in the semidilute entangled concentration regime. In addition the self-diffusion coefficient of the tracer Polystyrene chains can be detected for arbitrary concentrations. The measured cooperative diffusion coefficient is independent of the molecular weight of the tracer Polystyrene chains because it is a characteristic feature of the transient entanglement network.
