Magnetic Assembly and Pyrolysis of Functional Ferromagnetic Colloids into One-Dimensional Carbon Nanostructures

Bowles, Steven E.; Wu, Wei; Kowalewski, Tomasz; Schalnat, Matthew C.; Davis, R. J.; Pemberton, Jeanne E.; Shim, In‐Bo; Korth, Bryan D.; Pyun, Jeffrey

doi:10.1021/ja072757x

Cited by 66 publications

(47 citation statements)

References 17 publications

(9 reference statements)

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“…Polymer-coated magnetic colloid chains have been assembled to create carbon-particle chains after pyrolysis and magneticparticle removal. [216] Colloidal-crystal templating is a relatively mature technique for the preparation of 3D porous structures. [217] When colloidal Janus particles coated with titania on one hemisphere were used for templating, the titania coating was transferred onto the surface of the porous replica for catalytic reactions.…”

Section: Applications Of Colloidal Assemblymentioning

confidence: 99%

Colloidal Assembly: The Road from Particles to Colloidal Molecules and Crystals

2010

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Colloidal particles may be considered as building blocks for materials, just like atoms are the bricks of molecules, macromolecules, and crystals. Periodic arrays of colloids (colloidal crystals) have attracted much interest over the last two decades, largely because of their unique photonic properties. The archetype opal structures are based on close-packed arrays of spheres of submicrometer diameter. Interest in structuring materials at this length scale, but with more complex features and ideally by self-assembly processes, has led to much progress in controlling features of both building blocks and assemblies. The necessary ingredients include colloids, colloidal clusters, and colloidal "molecules" which have special shapes and the ability to bind directionally, the control over short-range and long-range interactions, and the capability to place and orientate these bricks. This Review highlights recent experimental and theoretical progress in the assembly of colloids larger than 50 nm.

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Section: Applications Of Colloidal Assemblymentioning

confidence: 99%

Colloidal Assembly: The Road from Particles to Colloidal Molecules and Crystals

2010

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“…In the majority of cases, these methods deal with a post-synthetic modification12 because monodisperse NPs are often obtained by solvothermal methods at high temperatures when capping ligand functionalities are either unstable or negatively influence the NP synthesis 13. For biomedical applications, iron oxide NPs are favored because they are generally stable in air and can be metabolized or degraded in vivo 14,15.…”

Section: Introductionmentioning

confidence: 99%

Magnetic nanoparticles with functional silanes: evolution of well-defined shells from anhydride containing silane

et al. 2009

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Modification of iron oxide nanoparticles (NPs) synthesized by high temperature solvothermal routes is carried out using two silanes: (i) N-(6-aminohexyl)-aminopropyltrimethoxysilane (AHAPS) where only one end of the molecule reacts with the surface Fe-OH groups and (ii) 3-(triethoxysilyl) propylsuccinic anhydride (SSA) where both ends are reactive with Fe-OH. Depending on the NP synthesis protocol, the amount of surface OH groups on the NPs may differ, however, for all the cases presented here, the comparatively low OH group density prevents a high density of AHAPS coverage, yielding NP aggregates instead of single particles in aqueous solutions. Alternatively, use of SSA containing two terminal functionalities, anhydride and siloxy, which are both reactive towards the NP surface, results in the formation of discrete dense polymeric shells, providing stability of individual NPs in water. The mechanism of the SSA shell formation is discussed. The evolution of the chemical transformations leads to shells of different thickness and density, yet this evolution can be halted by hydrolysis, after which the NPs are water soluble, negatively charged and exhibit excellent stability in aqueous media.

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“…Pyun et al have employed nitroxide-mediated radical polymerization (NMP) to prepare well-defined polymeric surfactants that stabilize magnetic nanoparticles. By casting nanoparticle dispersions from organic media onto surfaces, a diverse range of mesoscale morphologies have been observed, ranging from randomly entangled chains, field aligned 1D mesostructures, and nematiclike liquid crystal colloidal assemblies [124,133,134]. After ligand exchange to obtain a dispersion of polyacrylonitrile-stabilized ferromagnetic Co nanoparticles, a film was cast under an applied magnetic field [133].…”

Section: Magnetoresponsive Polymersmentioning

confidence: 99%