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Dissymmetric particles (janus particles), and method for synthesizing same by means of bipolar electrochemistry

a technology of dissymmetric particles and bipolar electrochemistry, which is applied in the field of dissymmetric particles, can solve the problems of not being compatible with a conventional industrial environment, unable to finely adjust the drive force of the modification, and difficult to prepare large quantities of particles, etc., and achieves the effect of high flexibility of us

Inactive Publication Date: 2014-01-30
CENT NAT DE LA RECHERCHE SCI +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Benefits of technology

The present invention provides a three-dimensional method for forming Janus particles with high flexibility in terms of material, size, shape, and nature of modification. The method allows for the formation of particles of micron or submicron size with an isotropic or anisotropic shape and a precise outline delimiting the modified part. In case of identical materials, voltage pulses can be applied to allow particles to rotate during the method. Additionally, a polarity reversal of the electrodes can switch the anodic and cathodic poles of the substrates during the method.

Problems solved by technology

However, this has the disadvantage of making the preparation of large quantities of particles rather difficult in as far as most techniques usually lead to equivalents of a monolayer of materials, since the particle modifications take place in a two-dimensional reaction space.
Currently, there are only three really specific three-dimensional methods, but which do not allow a fine adjusting of the drive force of the modification8,9,10.
This becomes a problem inherent to this approach when the objects to be functionalized are of micro- or nanometric size, since E must then reach values of the order of MV m−1.
This is not compatible with a conventional industrial environment, and particularly when using aqueous solutions, due to intrinsic parasitic reactions, which are accompanied by the formation of macroscopic gas bubbles at each electrode, such that it disrupts the orientation of objects in the electric field.
However, the technique used by Bradley et al. has the disadvantage of requiring the need to immobilize the objects on a surface such as to prevent them from rotating, meaning that the technique developed by Bradley et al. is in fact still a two-dimensional method and not a real three dimensional method taking place in the entire volume of the reactor.
However, considering that the modification of the particles is carried out in a capillary whereof the internal diameter cannot exceed a few hundred microns, the production of Janus particles is very slow, making this method unprofitable for industrial application.

Method used

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  • Dissymmetric particles (janus particles), and method for synthesizing same by means of bipolar electrochemistry
  • Dissymmetric particles (janus particles), and method for synthesizing same by means of bipolar electrochemistry
  • Dissymmetric particles (janus particles), and method for synthesizing same by means of bipolar electrochemistry

Examples

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example 1

[0086]Synthesis of micron Janus particles according to an embodiment of the invention, monofunctionnalized using the device represented in FIG. 2

[0087]Monofunctionnalized Janus particles were synthesized in accordance with the method according to an embodiment of the invention by using the electrodeposition device represented on FIG. 2 wherein:[0088]a potential difference E of the order of 2 kV is imposed between the electrodes, resulting in an electric field E of 100 kVm−1 in the electrodeposition cell,[0089]the separators are proton exchange membranes or sintered glass plates, and[0090]the electrodes 21, 22 are immersed in ethanol at −100° C. (to compensate for the effects of ohmic heating in the reactor) and at a distance of the order of 2 cm from each other.

[0091]The substrates 1 used are either carbon tubes (images 6A1, 6A2 and 6A3) or vitreous carbon beads (images 6B1, 6B2 and 6B3), the electrolytic solutions 40 are aqueous solutions which, as a source of electrodepositable ma...

example 2

[0094]Synthesis of micron Janus particles according to an embodiment of the invention, monofunctionnalized using the device represented on FIG. 3

[0095]Monofunctionnalized Janus particles were synthesized in accordance with the method according to an embodiment of the invention by using the electrodeposition device represented on FIG. 3 wherein:[0096]a potential difference E of the order of 6 kV is imposed between the electrodes, resulting in an electric field E of 20 MV m−1 in the electrodeposition cell,[0097]the separators are thin glass walls of 100 m and separated from each other also by 100 m;[0098]the substrates 1 used are either 1 carbon tubes (images 6A1 and 6A4) or vitreous carbon beads (images 6B1 and 6B4),[0099]the electrolytic solution 40 is a hydrogel of agar, which contains, as a source of electrodepositable material, the gold chloride AuCl4− at 10 mM (image 6A4) and gold chloride AuCl4− at 1 mM (image 6B4).

[0100]It was observed by scanning electron microscopy (SEM) the...

example 3

Synthesis of submicron Janus particles according to embodiments of the invention, monofunctionnalized by using the device represented on FIG. 2:

[0101]Monofunctionnalized Janus particles were synthesized in accordance with the method according to an embodiment of the invention by using the electrodeposition device represented on FIG. 2 wherein:[0102]a potential difference E of the order of 2 kV is imposed between the electrodes, resulting in an electric field of 100 kV m−1 in the electrodeposition cell;[0103]the separators are proton exchange membranes or sintered glass plates;[0104]the electrodes 21, 22 are immersed in ethanol at −100° C. (to compensate for the effects of ohmic heating in the reactor) and at a distance of the order of 2 cm from each other;[0105]the substrates 1 used are vitreous carbon beads; and[0106]the electrolytic solution 40 is a hydrogel of agar, which contains, as a source of electrodepositable material, gold chloride AuCl4− at 10 mM.

[0107]It was observed by ...

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Abstract

Dissymmetric particles also called Janus particles of micron or submicron size and methods of synthesis of Janus particles by bipolar electrochemistry, based on substrates of isotropic or anisotropic shape. The particles include an electrically conductive substrate having at least a chemically and / or physically modified part by deposit of a layer of electrochemically depositable material, and a non-modified part. The particles are of isotropic shape, and the layer of electrochemically depositable material has a specific shape delimited by a precise contour.

Description

PRIORITY[0001]The present application is a National Phase entry of PCT Application No. PCT / FR2011 / 053001, filed Dec. 15, 2011, which claims priority from FR Patent Application No. 1061031, filed Dec. 22, 2010, which applications are hereby incorporated by reference in their entireties.FIELD OF THE INVENTION[0002]The present invention generally relates to dissymmetric particles, also called Janus particles of micron or submicron size, as well as a method of synthesis of such particles by bipolar electrochemistry.REFERENCES[0003]In the description below, the references in exponent position refer to the list of references given after the examples.BACKGROUND OF THE INVENTION[0004]In Roman mythology, Janus is a god with a head but with two opposite faces. By analogy, the term “Janus” qualifies any dissymmetric object, such as a spherical particle whereof the two hemispheres would be physically and / or chemically different.[0005]In embodiments of the present invention, by the term Janus pa...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C25D13/12
CPCC25D13/12B01J13/04Y10T428/2991C25D5/02
Inventor LOGET, GABRIEL MICHEL PIERREKUHN, ALEXANDER
Owner CENT NAT DE LA RECHERCHE SCI
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