The Experts below are selected from a list of 1188 Experts worldwide ranked by ideXlab platform
Ian Manners - One of the best experts on this subject based on the ideXlab platform.
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capillary bound dense Micelle brush supports for continuous flow catalysis
Angewandte Chemie, 2021Co-Authors: Geyu Lin, Ian Manners, Jiandong Cai, Yan Sun, Yan Cui, Qiuwen Liu, Huibin QiuAbstract:Flow reactors are appealing alternatives to conventional batch reactors for heterogeneous catalysis. However, it remains a key challenge to firmly immobilize the catalysts in a facile and flexible manner and to simultaneously maintain a high catalytic efficiency and throughput. Herein, we introduce a dense Cylindrical Micelle brush support in glass capillary flow reactors through a living crystallization-driven self-assembly process initiated by pre-immobilized short Micelle seeds. The active hairy corona of these micellar brushes allows the flexible decoration of a diverse array of nanocatalysts, either through a direct capture process or an in situ growth method. The resulting flow reactors reveal excellent catalytic efficiency for a broad range of frequently utilized transformations, including organic reductions, Suzuki couplings, photolytic degradations, and multistep cascade reactions and the system was both recyclable and durable. Significantly, this approach is readily applicable to long capillaries, which enables the construction of flow reactors with remarkably higher throughput.
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uniform patchy and hollow rectangular platelet Micelles from crystallizable polymer blends
Science, 2016Co-Authors: Huibin Qiu, Mitchell A Winnik, Yang Gao, Charlotte E Boott, Oliver E C Gould, Robert L Harniman, Mervyn J Miles, Stephen E D Webb, Ian MannersAbstract:The preparation of colloidally stable, self-assembled materials with tailorable solid or hollow two-dimensional (2D) structures represents a major challenge. We describe the formation of uniform, monodisperse rectangular platelet Micelles of controlled size by means of seeded-growth methods that involve the addition of blends of crystalline-coil block copolymers and the corresponding crystalline homopolymer to Cylindrical Micelle seeds. Sequential addition of different blends yields solid platelet block coMicelles with concentric rectangular patches with distinct coronal chemistries. These complex nano-objects can be subject to spatially selective processing that allows their disassembly to form perforated platelets, such as well-defined hollow rectangular rings. The solid and hollow 2D Micelles provide a tunable platform for further functionalization and potential for a variety of applications.
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complex and hierarchical Micelle architectures from diblock copolymers using living crystallization driven polymerizations
Nature Materials, 2009Co-Authors: Torben Gadt, Nga Sze Ieong, Graeme Cambridge, Mitchell A Winnik, Ian MannersAbstract:Block copolymers consist of two or more chemically distinct polymer segments, or blocks, connected by a covalent link. In a selective solvent for one of the blocks, core–corona Micelle structures are formed. We demonstrate that living polymerizations driven by the epitaxial crystallization of a core-forming metalloblock represent a synthetic tool that can be used to generate complex and hierarchical Micelle architectures from diblock copolymers. The use of platelet Micelles as initiators enables the formation of scarf-like architectures in which Cylindrical Micelle tassels of controlled length are grown from specific crystal faces. A similar process enables the fabrication of brushes of Cylindrical Micelles on a crystalline homopolymer substrate. Living polymerizations driven by heteroepitaxial growth can also be accomplished and are illustrated by the formation of tri- and pentablock and scarf architectures with cylinder–cylinder and platelet–cylinder connections, respectively, that involve different core-forming metalloblocks. A synthetic tool that uses living polymerizations driven by epitaxial crystallization is shown to create a range of complex Micelle architectures made from diblock copolymers. Platelet Micelles act as initiators for the formation of scarf-like structures with micellar tassels of controlled length, grown from specific locations.
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complex and hierarchical Micelle architectures from diblock copolymers using living crystallization driven polymerizations
Nature Materials, 2009Co-Authors: Torben Gadt, Nga Sze Ieong, Graeme Cambridge, Mitchell A Winnik, Ian MannersAbstract:Block copolymers consist of two or more chemically distinct polymer segments, or blocks, connected by a covalent link. In a selective solvent for one of the blocks, core-corona Micelle structures are formed. We demonstrate that living polymerizations driven by the epitaxial crystallization of a core-forming metalloblock represent a synthetic tool that can be used to generate complex and hierarchical Micelle architectures from diblock copolymers. The use of platelet Micelles as initiators enables the formation of scarf-like architectures in which Cylindrical Micelle tassels of controlled length are grown from specific crystal faces. A similar process enables the fabrication of brushes of Cylindrical Micelles on a crystalline homopolymer substrate. Living polymerizations driven by heteroepitaxial growth can also be accomplished and are illustrated by the formation of tri- and pentablock and scarf architectures with cylinder-cylinder and platelet-cylinder connections, respectively, that involve different core-forming metalloblocks.
Torben Gadt - One of the best experts on this subject based on the ideXlab platform.
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complex and hierarchical Micelle architectures from diblock copolymers using living crystallization driven polymerizations
Nature Materials, 2009Co-Authors: Torben Gadt, Nga Sze Ieong, Graeme Cambridge, Mitchell A Winnik, Ian MannersAbstract:Block copolymers consist of two or more chemically distinct polymer segments, or blocks, connected by a covalent link. In a selective solvent for one of the blocks, core–corona Micelle structures are formed. We demonstrate that living polymerizations driven by the epitaxial crystallization of a core-forming metalloblock represent a synthetic tool that can be used to generate complex and hierarchical Micelle architectures from diblock copolymers. The use of platelet Micelles as initiators enables the formation of scarf-like architectures in which Cylindrical Micelle tassels of controlled length are grown from specific crystal faces. A similar process enables the fabrication of brushes of Cylindrical Micelles on a crystalline homopolymer substrate. Living polymerizations driven by heteroepitaxial growth can also be accomplished and are illustrated by the formation of tri- and pentablock and scarf architectures with cylinder–cylinder and platelet–cylinder connections, respectively, that involve different core-forming metalloblocks. A synthetic tool that uses living polymerizations driven by epitaxial crystallization is shown to create a range of complex Micelle architectures made from diblock copolymers. Platelet Micelles act as initiators for the formation of scarf-like structures with micellar tassels of controlled length, grown from specific locations.
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complex and hierarchical Micelle architectures from diblock copolymers using living crystallization driven polymerizations
Nature Materials, 2009Co-Authors: Torben Gadt, Nga Sze Ieong, Graeme Cambridge, Mitchell A Winnik, Ian MannersAbstract:Block copolymers consist of two or more chemically distinct polymer segments, or blocks, connected by a covalent link. In a selective solvent for one of the blocks, core-corona Micelle structures are formed. We demonstrate that living polymerizations driven by the epitaxial crystallization of a core-forming metalloblock represent a synthetic tool that can be used to generate complex and hierarchical Micelle architectures from diblock copolymers. The use of platelet Micelles as initiators enables the formation of scarf-like architectures in which Cylindrical Micelle tassels of controlled length are grown from specific crystal faces. A similar process enables the fabrication of brushes of Cylindrical Micelles on a crystalline homopolymer substrate. Living polymerizations driven by heteroepitaxial growth can also be accomplished and are illustrated by the formation of tri- and pentablock and scarf architectures with cylinder-cylinder and platelet-cylinder connections, respectively, that involve different core-forming metalloblocks.
Jyongsik Jang - One of the best experts on this subject based on the ideXlab platform.
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sensing behaviors of polypyrrole nanotubes prepared in reverse microemulsions effects of transducer size and transduction mechanism
Journal of Physical Chemistry B, 2006Co-Authors: Hyeonseok Yoon, Mincheol Chang, Jyongsik JangAbstract:Polypyrrole (PPy) nanotubes with different diameters were readily fabricated using Cylindrical Micelle templates in sodium bis(2-ethylhexyl) sulfosuccinate (AOT) reverse microemulsions. Interestingly, Raman spectroscopy and ultraviolet (UV)-visible spectroscopy revealed that the PPy nanotubes with smaller diameters had a more extended conjugation length as well as a higher oxidation level. The PPy nanotubes were deposited onto a microelectrode array and were exposed to chemical vapor and electromagnetic radiation: typically, NH(3) vapor and UV light were chosen. The electrical response of PPy nanotubes to two different kinds of analytes was strongly dependent on their diameters. Moreover, since the small dimensions of PPy nanotubes facilitated the interaction between nanotubes and analytes, the PPy nanotube sensors showed conspicuously enhanced responses compared with conventional PPy.
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formation mechanism of conducting polypyrrole nanotubes in reverse Micelle systems
Langmuir, 2005Co-Authors: Jyongsik Jang, Hyeonseok YoonAbstract:Polypyrrole (PPy) nanotubes were readily fabricated through chemical oxidation polymerization in sodium bis(2-ethylhexyl) sulfosuccinate (AOT) reverse (water-in-oil) emulsions. The reverse Cylindrical Micelle phase was characterized, and the key factors affecting the formation of PPy nanotubes were systematically inspected. AOT reverse Cylindrical Micelles were prepared via a cooperative interaction between an aqueous FeCl3 solution and AOT in an apolar solvent. In the H2O/FeCl3/AOT/apolar solvent system, the aqueous FeCl3 solution played a role in increasing the ionic strength and decreasing the second critical Micelle concentration of AOT. As a result, AOT reverse Cylindrical Micelles could be spontaneously formed in an apolar solvent. In addition, iron cations were adsorbed to the anionic AOT headgroups that were capable of extracting metal cations from the aqueous core. Under these conditions, the addition of pyrrole monomer resulted in the chemical oxidation polymerization of the corresponding monome...
Hyeonseok Yoon - One of the best experts on this subject based on the ideXlab platform.
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sensing behaviors of polypyrrole nanotubes prepared in reverse microemulsions effects of transducer size and transduction mechanism
Journal of Physical Chemistry B, 2006Co-Authors: Hyeonseok Yoon, Mincheol Chang, Jyongsik JangAbstract:Polypyrrole (PPy) nanotubes with different diameters were readily fabricated using Cylindrical Micelle templates in sodium bis(2-ethylhexyl) sulfosuccinate (AOT) reverse microemulsions. Interestingly, Raman spectroscopy and ultraviolet (UV)-visible spectroscopy revealed that the PPy nanotubes with smaller diameters had a more extended conjugation length as well as a higher oxidation level. The PPy nanotubes were deposited onto a microelectrode array and were exposed to chemical vapor and electromagnetic radiation: typically, NH(3) vapor and UV light were chosen. The electrical response of PPy nanotubes to two different kinds of analytes was strongly dependent on their diameters. Moreover, since the small dimensions of PPy nanotubes facilitated the interaction between nanotubes and analytes, the PPy nanotube sensors showed conspicuously enhanced responses compared with conventional PPy.
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formation mechanism of conducting polypyrrole nanotubes in reverse Micelle systems
Langmuir, 2005Co-Authors: Jyongsik Jang, Hyeonseok YoonAbstract:Polypyrrole (PPy) nanotubes were readily fabricated through chemical oxidation polymerization in sodium bis(2-ethylhexyl) sulfosuccinate (AOT) reverse (water-in-oil) emulsions. The reverse Cylindrical Micelle phase was characterized, and the key factors affecting the formation of PPy nanotubes were systematically inspected. AOT reverse Cylindrical Micelles were prepared via a cooperative interaction between an aqueous FeCl3 solution and AOT in an apolar solvent. In the H2O/FeCl3/AOT/apolar solvent system, the aqueous FeCl3 solution played a role in increasing the ionic strength and decreasing the second critical Micelle concentration of AOT. As a result, AOT reverse Cylindrical Micelles could be spontaneously formed in an apolar solvent. In addition, iron cations were adsorbed to the anionic AOT headgroups that were capable of extracting metal cations from the aqueous core. Under these conditions, the addition of pyrrole monomer resulted in the chemical oxidation polymerization of the corresponding monome...
Daniel E Resasco - One of the best experts on this subject based on the ideXlab platform.
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dispersion of single walled carbon nanotubes in aqueous solutions of the anionic surfactant naddbs
Journal of Physical Chemistry B, 2003Co-Authors: Olga Matarredona, Heather Rhoads, Zhongrui Li, Jeffrey H Harwell, Leandro Balzano, Daniel E ResascoAbstract:The insolubility of single-walled carbon nanotubes (SWNT) in either water or organic solvents has been a limitation for the practical application of this unique material. Recent studies have demonstrated that the suspendability of SWNT can be greatly enhanced by employing appropriate surfactants. Although the efficiency of anionic, cationic, and nonionic surfactants has been demonstrated to different extents, the exact mechanism by which carbon nanotubes and the different surfactants interact is still uncertain. To deepen the understanding of this interfacial phenomenon, we have investigated the effects of chemical modifications of the surface on the extent of nanotube-surfactant interaction. Such changes in the surface chemistry of the SWNT can be achieved by simply varying the pretreatment method, which can be acidic or basic. We have found that intrinsic surface properties such as the PZC (point of zero charge) are greatly affected by the purification method. That is, the electrical charge of the SWNT surface varies with the pH of the surrounding media. However, it has been found that during the adsorption of the anionic surfactant sodium dodecylbenzenesulfonate (NaDDBS) on SWNT Coulombic forces do not play a central role, but are overcome by the hydrophobic interactions between the surfactant tail and the nanotube walls. Only at pH values far from the PZC do the Coulombic forces become important. The hydrophobic forces between the surfactant tail and the nanotube determine the structure of the surfactant-stabilized nanotubes. In such a structure, each nanotube is covered by a monolayer of surfactant molecules in which the heads form a compact outer surface while the tails remain in contact with the nanotube walls. It is important to note that although the final configuration can be described as a Cylindrical Micelle with a nanotube in the center, the mechanism of formation of this structure does not proceed by incorporation of a nanotube into a Micelle, but rather by a two-step adsorption that ends up in the formation of a surfactant monolayer.
