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

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.

1 . Janus particles of micron or submicron size, each particle comprising:
 an electrically conductive substrate having at least one chemically and/or physically modified part by deposit of a layer of electrochemically depositable material, and an unmodified part,   wherein said particles are of isotropic shape, and   wherein the layer of electrochemically depositable material has a specific shape delimited by a precise contour.   
     
     
         2 . The particles according to  claim 1 , wherein the particles exhibit at least two chemically and/or physically modified parts. 
     
     
         3 . The particles according to  claim 2 , wherein one of said at least two modified parts is covered with a layer of a first electrochemically depositable material, and the other part of said at least two modified parts is covered with a layer of a second electrochemically depositable material different from said first material. 
     
     
         4 . The particles according to  claim 3 , wherein said first and second materials are electrically conductive materials. 
     
     
         5 . The particles according to  claim 3 , wherein said first and second materials are insulating materials. 
     
     
         6 . The particles according to  claim 3 , wherein said first material is an electrically conductive material and said second material is an insulating material. 
     
     
         7 . The particles according to  claim 1 , wherein the shape of the layer of electrochemically depositable material is a circular line of variable diameter, a point, a hemisphere, or a portion of a hemisphere. 
     
     
         8 . The particles according to  claim 1 , wherein electrically conductive materials forming the substrate of the particles comprise metals or semi-conductive metals. 
     
     
         9 . The particle according to  claim 8 , wherein the material comprises a metal selected from the group consisting of gold, copper, zinc, silver, platinum and nickel. 
     
     
         10 . The particles according to  claim 8 , wherein the material comprises a semi-conductive metal, selected from the group consisting of ZnO, CdS, CdSe and TiO 2 . 
     
     
         11 . The particles according to  claim 3 , wherein the insulating materials are polymeric materials, organic molecules, silica-based sol-gel materials, metal oxides or metal salts. 
     
     
         12 . The particles according to  claim 11 , wherein the polymeric material are chosen from among the families of polypyrroles, polyanilines and polythiophenes. 
     
     
         13 . The particles according to  claim 1 , wherein the substrate is a bead of a conductive or semi-conductive material. 
     
     
         14 . The particles according to  claim 13 , wherein the substrate is a bead of carbon or metal or metal alloy. 
     
     
         15 . An electrochemical method of synthesis of Janus particles based on submicron or micron electrically conductive substrates, the method comprising:
 A. introducing said substrates and at least one source of electrochemically depositable material in an electrolytic solution contained in an electrodeposition cell defined by two separators, said cell being positioned between two electrodes; and   B. applying a potential difference E between the two electrodes such as to create a sufficiently strong electric field E and for a sufficiently long period of time for forming Janus particles.   
     
     
         16 . The method according to  claim 15 , wherein the separators are not permeable to the substrates, and are placed in a same reactor of electrodeposition containing the electrolytic solution and the electrodes, by being positioned between said electrodes such as to define:
 the electrodeposition cell wherein the substrates and the source(s) of electrically conductive material are put in solution,   a cathodic compartment, incorporating the electrode serving as cathode and adjacent to one of said separators, and   an anodic compartment, incorporating the electrode serving as anode and adjacent to the other separator.   
     
     
         17 . The method according to  claim 15 , wherein the separators of the electrodeposition cell are in a waterproof material. 
     
     
         18 . The method according to  claim 15 , wherein the at least one source of electrochemically depositable material is selected from the group consisting of metal ions, semi-conductors formed from metal salts, electro-polymerizable monomers, organic electro-crystallizable salts, inorganic electro-crystallizable salts, organic electro-graftable molecules, electrophoretic paints and precursors of silica-based sol-gel materials. 
     
     
         19 . The method according to  claim 15 , wherein the at least one source of electrochemically depositable material is selected from the group consisting of monomers derived from pyrrole, aniline and thiophene. 
     
     
         20 . The method according to  claim 15 , wherein the at least one source of the material is selected from the group consisting of precursors of alkoxysilane type which are selected from methyl trimethoxysilane (MTMS), tetraethoxysilane (TEOS), methyltriethoxylsilane (MTES) dimethyldiethoxysilane, and combinations thereof. 
     
     
         21 . The method according to  claim 15 , wherein the at least one source of the material is selected from the group consisting of metal ions of gold, copper, zinc, silver, platinum and nickel. 
     
     
         22 . The method according to  claim 15 , wherein before application of the potential difference E between the two electrodes, a shape of the layer of the electrochemically depositable material is defined. 
     
     
         23 . The method according to  claim 15 , wherein the electrolytic solution is an aqueous solution. 
     
     
         24 . The method according to  claim 15 , wherein the electrolytic solution is an aqueous solution, a non-aqueous solvent solution, or a combination thereof. 
     
     
         25 . The method according to  claim 15 , wherein the substrates are particles of isotropic shape. 
     
     
         26 . The method according to  claim 15 , wherein the substrates are particles of anisotropic shape. 
     
     
         27 . The method according to  claim 15 , wherein the substrates are beads or nanotubes of carbon or metal. 
     
     
         28 . The method according to  claim 25 , wherein the electrolytic solution is in the form of a gel. 
     
     
         29 . The method according to  claim 28 , wherein the electrolytic solution is a hydrogel. 
     
     
         30 . A device for implementing the method according to  claim 16 , wherein the device comprises: an electrodeposition cell containing the electrolytic solution, said cell being bounded by separators into a sealing material, outside which electrodes are positioned contiguously.