The Experts below are selected from a list of 234 Experts worldwide ranked by ideXlab platform
Markus Gallei - One of the best experts on this subject based on the ideXlab platform.
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molecular ring rotation in poly Vinylferrocene
Physical Chemistry Chemical Physics, 2016Co-Authors: Markus Appel, Markus Gallei, B Frick, Johannes Elbert, Bernd StuhnAbstract:We investigate the ring rotation dynamics in poly(Vinylferrocene) (PVFc) using incoherent neutron spectroscopy. PVFc contains ferrocene units laterally attached to a polymer backbone, allowing for one cyclopentadienyl ring of the organometallic sandwich structure of ferrocene to undergo rotational jump diffusion. The barrier of rotation is found to be broadly distributed, but the dynamics can be well described using a rotation rate distribution model which is well known from the description of methyl group rotation in glassy polymers. As necessary information for the analysis of quasielastic scattering data, we measure the static structure factor of the polymer using polarized neutron diffraction. Neutron time-of-flight and backscattering data are then combined and consistently modeled over the large temperature range from 80 K to 350 K yielding an Arrhenius behavior of the jump rate distribution. The mean value of potential barrier distribution is found to be 〈EA〉 = 9.61(2) kJ mol−1 with a root mean square width of σE = 3.12(1) kJ mol−1, being the result of superposition of constant intramolecular and heterogeneous intermolecular rotational barriers.
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the renaissance of side chain ferrocene containing polymers scope and limitations of Vinylferrocene and ferrocenyl methacrylates
Macromolecular Chemistry and Physics, 2014Co-Authors: Markus GalleiAbstract:The synthesis of metal-containing polymers and block copolymers has led to a rapidly expanding field of research interest for manifold potential applications. Within this contribution, some recent advances in the field of side-chain ferrocene-containing polymers focusing on poly(Vinylferrocene) and poly(ferrocenyl methacrylates) are presented. The synthetic developments shown focus on living and controlled polymerizations, as well as surface-initiated polymerization strategies. First attempts and recent developments for these novel redox-responsive materials toward feasible applications are addressed.
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The Renaissance of Side‐Chain Ferrocene‐Containing Polymers: Scope and Limitations of Vinylferrocene and Ferrocenyl Methacrylates
Macromolecular Chemistry and Physics, 2014Co-Authors: Markus GalleiAbstract:The synthesis of metal-containing polymers and block copolymers has led to a rapidly expanding field of research interest for manifold potential applications. Within this contribution, some recent advances in the field of side-chain ferrocene-containing polymers focusing on poly(Vinylferrocene) and poly(ferrocenyl methacrylates) are presented. The synthetic developments shown focus on living and controlled polymerizations, as well as surface-initiated polymerization strategies. First attempts and recent developments for these novel redox-responsive materials toward feasible applications are addressed.
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redox responsive block copolymers poly Vinylferrocene b poly lactide diblock and miktoarm star polymers and their behavior in solution
Organometallics, 2013Co-Authors: Jan Morsbach, Holger Frey, Johannes Elbert, Adrian Natalello, Svenja Winzen, Anja Kroeger, Markus GalleiAbstract:The synthesis of diblock and miktoarm star polymers containing poly(Vinylferrocene) (PVFc) and poly(l-lactide) (PLA) blocks is introduced. End functionalization of PVFc was carried out via end capping of living carbanionic PVFc chains with benzyl glycidyl ether (BGE). By hydrogenolysis of the benzyl protecting group a dihydroxyl end-functionalized PVFc was obtained. Both monohydroxyl- and dihydroxyl-functionalized PVFcs have been utilized as macroinitiators for the subsequent polymerization of l-lactide via catalytic ring-opening polymerization. A series of block copolymers and AB2 miktoarm star polymers was synthesized with varied PLA chain lengths. All polymers were characterized in detail, using 1H NMR spectroscopy, size exclusion chromatography (SEC), and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-ToF). The molecular weight of the block copolymers and AB2 miktoarm star polymers are in the range of 8000–15000, containing a PVFc block of weight 7800. In addition,...
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patchy nanocapsules of poly Vinylferrocene based block copolymers for redox responsive release
ACS Nano, 2012Co-Authors: Roland H Staff, Markus Gallei, Markus Mazurowski, Matthias Rehahn, Rudiger Berger, Katharina Landfester, Daniel CrespyAbstract:Nanocapsules composed of a poly(Vinylferrocene)-block-poly(methyl methacrylate) shell and a hydrophobic liquid core are prepared in water. The nanocapsule shells display a patchy structure with poly(Vinylferrocene) patches with sizes of 25 ± 3 nm surrounded by poly(methyl methacrylate). The functional nanopatches can be selectively oxidized, thereby influencing the colloidal morphology and introducing polar domains in the nanocapsule shell. The hydrophobic to hydrophilic transition in the redox-responsive nanopatches can be advantageously used to release a hydrophobic payload encapsulated in the core by an oxidation reaction.
Nuran Özçiçek Pekmez - One of the best experts on this subject based on the ideXlab platform.
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Carbon nanotubes/alizarin red S–poly(Vinylferrocene) modified glassy carbon electrode for selective determination of dopamine in the presence of ascorbic acid
Journal of Solid State Electrochemistry, 2012Co-Authors: Uğur Tamer, Nuran Özçiçek PekmezAbstract:A modified electrode was fabricated by electrochemical formation of poly(Vinylferrocene) on the multi-wall carbon nanotube-alizarin red S matrix covered glassy carbon electrode. A higher electrochemical activity was obtained to the electrocatalytic oxidation of dopamine. The electrode surface was characterized electrochemically and spectroscopically. Poly(Vinylferrocene) (PVF) in electrode was used as an electron transfer mediator in the electrochemical oxidation of compounds due to its perfect reversible redox properties. Multi-wall carbon nanotubes (MWCNTs) / alizarin red S (ARS)–PVF electrode was used to the determination of dopamine in the presence of ascorbic acid in 0.1 M sulphate buffer solution at pH 7. The performance of the MWCNTs/ARS–PVF electrode was evaluated by DPV and amperometry.
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carbon nanotubes alizarin red s poly Vinylferrocene modified glassy carbon electrode for selective determination of dopamine in the presence of ascorbic acid
Journal of Solid State Electrochemistry, 2012Co-Authors: Uğur Tamer, Nuran Özçiçek PekmezAbstract:A modified electrode was fabricated by electrochemical formation of poly(Vinylferrocene) on the multi-wall carbon nanotube-alizarin red S matrix covered glassy carbon electrode. A higher electrochemical activity was obtained to the electrocatalytic oxidation of dopamine. The electrode surface was characterized electrochemically and spectroscopically. Poly(Vinylferrocene) (PVF) in electrode was used as an electron transfer mediator in the electrochemical oxidation of compounds due to its perfect reversible redox properties. Multi-wall carbon nanotubes (MWCNTs) / alizarin red S (ARS)–PVF electrode was used to the determination of dopamine in the presence of ascorbic acid in 0.1 M sulphate buffer solution at pH 7. The performance of the MWCNTs/ARS–PVF electrode was evaluated by DPV and amperometry.
Koichi Aoki - One of the best experts on this subject based on the ideXlab platform.
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enhancement of electrochemical activity by small sizing the Vinylferrocene immobilized polystyrene latex particles
Langmuir, 2004Co-Authors: Cuiling Xu, Koichi AokiAbstract:Voltammetry of Vinylferrocene (VFc)-immobilized polystyrene(PS)-based latex particles was carried out in aqueous suspensions by changing the size of latex particles in order to investigate the depe...
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partial charge transfer of poly Vinylferrocene coated latex particles adsorbed on pyrolytic graphite electrode
Electrochemistry Communications, 2003Co-Authors: Cuiling Xu, Jingyuan Chen, Koichi AokiAbstract:As a model of an electrode reaction of a big particle, Vinylferrocene immobilized on polystyrene latex particles were synthesized by copolymerization with styrene sulfonate and styrene. They had almost mono-dispersed spheres with 1.2 lm in diameter, and each had 3.1 � 10 7 ferrocene units. The particles adsorbed on pyrolytic graphite electrode (PGE) showed the redox activity for the ferrocene unit in NaBF4 aqueous solution. Particles without the sulfonate group had no electroactivity, and hence the electroactivity needs ionic micro-environment around the ferrocene unit. From the faradaic charge of the ferrocene unit, the electroactive sites per particle were estimated to be about 8% of the whole immobilized ferrocene units. A model of this partial charge transfer was proposed, in which the particles are adsorbed in hollows of the rough surface of the PGE. 2003 Elsevier Science B.V. All rights reserved.
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suspensions of poly Vinylferrocene coated latex particles
Journal of Electroanalytical Chemistry, 2003Co-Authors: Jingyuan Chen, Cuiling Xu, Koichi AokiAbstract:Abstract Aqueous suspensions of micrometer-sized latex particles coated with poly(Vinylferrocene) showed voltammetric responses of poly(Vinylferrocene) at the nitrobenzene(NB)-coated pyrolytic graphite electrode (PGE), although these were electroinactive at conventional metal electrodes. The whole process consists of diffusion of the latex particles in the water phase, dissolution of the particles in the NB film, the electrode reaction of dissolved poly(Vinylferrocene), and the partition of poly(Vinylferrocene) to the aqueous phase. The rate-determining process was in the dissolution kinetics, and hence the voltammogram showed surface waves of poly(Vinylferrocene) immobilized on the NB film. The amount of the redox charge increased with time of the immersion of the PGE into the suspension. The latex particles were synthesized with copolymerization of styrene and Vinylferrocene on polystyrene latex particles. One latex particle contains 2.1×10 7 ferrocene moieties in the overlayer of the core polystyrene.
Uğur Tamer - One of the best experts on this subject based on the ideXlab platform.
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Carbon nanotubes/alizarin red S–poly(Vinylferrocene) modified glassy carbon electrode for selective determination of dopamine in the presence of ascorbic acid
Journal of Solid State Electrochemistry, 2012Co-Authors: Uğur Tamer, Nuran Özçiçek PekmezAbstract:A modified electrode was fabricated by electrochemical formation of poly(Vinylferrocene) on the multi-wall carbon nanotube-alizarin red S matrix covered glassy carbon electrode. A higher electrochemical activity was obtained to the electrocatalytic oxidation of dopamine. The electrode surface was characterized electrochemically and spectroscopically. Poly(Vinylferrocene) (PVF) in electrode was used as an electron transfer mediator in the electrochemical oxidation of compounds due to its perfect reversible redox properties. Multi-wall carbon nanotubes (MWCNTs) / alizarin red S (ARS)–PVF electrode was used to the determination of dopamine in the presence of ascorbic acid in 0.1 M sulphate buffer solution at pH 7. The performance of the MWCNTs/ARS–PVF electrode was evaluated by DPV and amperometry.
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carbon nanotubes alizarin red s poly Vinylferrocene modified glassy carbon electrode for selective determination of dopamine in the presence of ascorbic acid
Journal of Solid State Electrochemistry, 2012Co-Authors: Uğur Tamer, Nuran Özçiçek PekmezAbstract:A modified electrode was fabricated by electrochemical formation of poly(Vinylferrocene) on the multi-wall carbon nanotube-alizarin red S matrix covered glassy carbon electrode. A higher electrochemical activity was obtained to the electrocatalytic oxidation of dopamine. The electrode surface was characterized electrochemically and spectroscopically. Poly(Vinylferrocene) (PVF) in electrode was used as an electron transfer mediator in the electrochemical oxidation of compounds due to its perfect reversible redox properties. Multi-wall carbon nanotubes (MWCNTs) / alizarin red S (ARS)–PVF electrode was used to the determination of dopamine in the presence of ascorbic acid in 0.1 M sulphate buffer solution at pH 7. The performance of the MWCNTs/ARS–PVF electrode was evaluated by DPV and amperometry.
Holger Frey - One of the best experts on this subject based on the ideXlab platform.
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redox responsive block copolymers poly Vinylferrocene b poly lactide diblock and miktoarm star polymers and their behavior in solution
Organometallics, 2013Co-Authors: Jan Morsbach, Holger Frey, Johannes Elbert, Adrian Natalello, Svenja Winzen, Anja Kroeger, Markus GalleiAbstract:The synthesis of diblock and miktoarm star polymers containing poly(Vinylferrocene) (PVFc) and poly(l-lactide) (PLA) blocks is introduced. End functionalization of PVFc was carried out via end capping of living carbanionic PVFc chains with benzyl glycidyl ether (BGE). By hydrogenolysis of the benzyl protecting group a dihydroxyl end-functionalized PVFc was obtained. Both monohydroxyl- and dihydroxyl-functionalized PVFcs have been utilized as macroinitiators for the subsequent polymerization of l-lactide via catalytic ring-opening polymerization. A series of block copolymers and AB2 miktoarm star polymers was synthesized with varied PLA chain lengths. All polymers were characterized in detail, using 1H NMR spectroscopy, size exclusion chromatography (SEC), and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-ToF). The molecular weight of the block copolymers and AB2 miktoarm star polymers are in the range of 8000–15000, containing a PVFc block of weight 7800. In addition,...
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water soluble poly Vinylferrocene b poly ethylene oxide diblock and miktoarm star polymers
Macromolecules, 2012Co-Authors: Christoph Tonhauser, Markus Gallei, Markus Mazurowski, Matthias Rehahn, Holger FreyAbstract:We describe the synthesis of water-soluble diblock and miktoarm star polymers consisting of poly(Vinylferrocene) (PVFc) and poly(ethylene oxide) (PEO) blocks. First, end-functionalized poly(Vinylferrocene) was generated by end-capping the living carbanionic PVFc chains with benzyl glycidyl ether (BGE) or ethoxy ethyl glycidyl ether (EEGE). Acidic hydrolysis of the EEGE-terminated PVFc partially oxidized the PVFc backbone. However, the dihydroxyl end-functional PVFc was obtained in quantitative yields by hydrogenolysis of the BGE-terminated PVFc. A series of block copolymers and AB2 miktoarm star copolymers was obtained in a second polymerization step, utilizing the respective end-functionalized PVFc as a macroinitiator for the ring-opening polymerization (ROP) of ethylene oxide. All polymers were analyzed in detail, using NMR spectroscopy and size-exclusion chromatography (SEC). Online SEC-viscosimetry as well as MALLS was carried out, confirming the formation of miktoarm structures. Quantitative function...
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styrene Vinylferrocene random and block copolymers by tempo mediated radical polymerization
Macromolecular Rapid Communications, 1999Co-Authors: Martin Baumert, Jorg Frohlich, Markus Stieger, Holger Frey, Rolf Mulhaupt, Herbert PlenioAbstract:TEMPO-mediated free radical polymerization was employed for homo- and copolymerization of Vinylferrocene (Vfc). Homopolymerization of Vfc resulted in relatively narrow polydispersities (Mw/Mn = 1.24–1.8), however, molecular weights were limited to 4 800. Copolymerization with styrene afforded random copolymers with molecular weights (Mn) up to 10 000, narrow polydispersity (1.2 > Mw/Mn > 1.4) and up to 42 mol-% Vfc. Block copolymers with PS block and P(S-co-Vfc) block with molecular weights (Mn) in the range of 9 000 to 17 600 (Mw/Mn > 1.3) were also prepared with up to 17 mol-% Vinylferrocene. DSC revealed two glass transition temperatures (Tg) evidencing phase separation.
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Styrene‐Vinylferrocene random and block copolymers by TEMPO‐mediated radical polymerization
Macromolecular Rapid Communications, 1999Co-Authors: Martin Baumert, Jorg Frohlich, Markus Stieger, Holger Frey, Rolf Mulhaupt, Herbert PlenioAbstract:TEMPO-mediated free radical polymerization was employed for homo- and copolymerization of Vinylferrocene (Vfc). Homopolymerization of Vfc resulted in relatively narrow polydispersities (Mw/Mn = 1.24–1.8), however, molecular weights were limited to 4 800. Copolymerization with styrene afforded random copolymers with molecular weights (Mn) up to 10 000, narrow polydispersity (1.2 > Mw/Mn > 1.4) and up to 42 mol-% Vfc. Block copolymers with PS block and P(S-co-Vfc) block with molecular weights (Mn) in the range of 9 000 to 17 600 (Mw/Mn > 1.3) were also prepared with up to 17 mol-% Vinylferrocene. DSC revealed two glass transition temperatures (Tg) evidencing phase separation.
