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    True Bulk Synthesis of Janus Objects by Bipolar Electrochemistry (2012) Adv. Mater.

True Bulk Synthesis of Janus Objects by Bipolar Electrochemistry (2012) Adv. Mater.

Janus particles have different features/chemistry on two opposite sides (see figure). So far, they have been obtained mainly by two-dimensional synthetic methods, which are able to break the symmetry but limit the amount of produced particles. A true bulk approach, based on bipolar electrochemistry, is presented that allows the straightforward synthesis of such asymmetric micro- and nano-objects. Lien vers la publication
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    Indirect Bipolar Electrodeposition J.Am.Chem.Soc. 134 (2012) 20033

Indirect Bipolar Electrodeposition J.Am.Chem.Soc. 134 (2012) 20033

Based on the principles of bipolar electrochemistry, localized pH gradients are generated at the surface of conducting particles in solution. This allows the toposelective deposition of inorganic and organic polymer layers via a pH-triggered precipitation mechanism. Due to the intrinsic symmetry breaking of the process, the concept can be used to generate in a straightforward way Janus particles, with one section consisting of deposits obtained from non-electroactive precursors. These indirect electrodeposits, such as SiO2, TiO2, or electrophoretic paints, can be further used as an immobilization matrix for other species like dyes or nanoparticles, thus opening promising perspectives for the synthesis of a variety of bifunctional objects with a controlled shape. Lien vers la publication
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    Wireless Electrografting of Molecular Layers for Janus Particle Synthesis Chem.Eur. J. 19 (2013) 1577

Wireless Electrografting of Molecular Layers for Janus Particle Synthesis Chem.Eur. J. 19 (2013) 1577

Glassy carbon beads are selectively functionalized on one side with an ultrathin organic layer by bipolar electrochemical reduction of diazonium salts to give Janus-type beads with a hybrid organic–inorganic composition (see scheme). The presence of the grafted organic layers is revealed either by co-adsorption of gold nanoparticles or by coupling with a fluorescent molecule. Lien vers online library
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    Controlled Orientation of Asymmetric Copper Deposits on Carbon Microobjects by Bipolar Electrochemistry J. Phys. Chem. C 116 (2012) 22021

Controlled Orientation of Asymmetric Copper Deposits on Carbon Microobjects by Bipolar Electrochemistry J. Phys. Chem. C 116 (2012) 22021

Asymmetric particles of various chemical compositions have attracted great attention because of their application potential in different areas, ranging from photosplitting of water to autonomous swimmers. In this context, the spatial arrangement of the different components can be of major importance. We report here a bulk procedure based on bipolar electrochemistry that allows generating asymmetric particles with a highly controlled spatial orientation of a metal deposit on a carbon substrate. Two fundamentally different topologies of the metal deposit can be obtained as a function of controllable experimental parameters like the orientation and amplitude of the electric field as well as the viscosity of the medium. Lien vers la publication
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    Direct Visualization of Symmetry Breaking During Janus Nanoparticle Formation (2012) Small

Direct Visualization of Symmetry Breaking During Janus Nanoparticle Formation (2012) Small

The straight-forward synthesis of Janus nanoparticles composed of Ag and AgBr is reported. For their formation, cucurbituril (CB)-stabilized AgBr nanoparticles are first generated in water by precipitation. Subsequent irradiation with an electron beam transforms a fraction of each AgBr nanoparticle into Ag0, leading to well-defined Janus particles, stabilized by the binding of CB to the surface of both AgBr and Ag0. With the silver ion reduction being triggered by the electron beam, the progress of the transformation can be directly monitored with a transmission electron microscope.   Lien: vers la publication