Patent Application: US-201113996783-A

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:
fig1 , which is discussed in the description of the prior art , represents a block diagram of an example of a device for implementing the method according to a first embodiment of the invention . this figure particularly shows that sufficient polarization of a conductive particle makes it possible to break the symmetry . fig2 and 3 represent block diagrams of an electrodeposition device for implementing the method according to embodiments of the invention , each corresponding to a different embodiment . these figures show that the electrodeposition device comprises an electrodeposition cell 3 , defined by two separators 31 , 32 , and is arranged between two electrodes 21 , 22 . the operating principle for the two embodiments of the electrodeposition device , which is the same one , comprises the following steps : a . micron or submicron substrates 1 are introduced and at least one source 41 of an electrochemically material depositable in an electrolytic solution 40 contained in the cell 3 ; b . a potential difference e is applied between the two electrodes 21 , 22 such as to create a sufficiently strong electric field e and during a sufficiently long period for forming janus particles . fig3 more particularly represents an electrodeposition device 3 , which comprises an electrodeposition reactor 5 containing the electrolytic solution 40 , the electrodes 21 and 22 which are immersed into the electrolytic solution , and the separators 31 , 32 which consist of membranes or plates which are non - permeable to the substrates . these membranes 31 , 32 are arranged between the electrodes 21 , 22 such as to define : the electrodeposition cell 3 itself , wherein the substrates 1 of an electrically conductive material and the source 41 are introduced in order to put them in solution , a cathodic compartment 51 , which includes the electrode serving as cathode 21 and is adjacent to one of the membranes 31 , and an anodic compartment 52 , which includes the electrode serving as anode 22 and is adjacent to the other membrane 32 . fig4 more particularly represents an electrodeposition device 3 wherein the separators 31 , 32 are in watertight material ( glass or plexiglas ®). they delimit the electrodeposition cell 3 containing the electrolytic solution 40 and outside which 3 the electrodes 21 , 22 are contiguously arranged . the following examples illustrate the invention without however limiting its scope . synthesis of micron janus particles according to an embodiment of the invention , monofunctionnalized using the device represented in fig2 monofunctionnalized janus particles were synthesized in accordance with the method according to an embodiment of the invention by using the electrodeposition device represented on fig2 wherein : 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 , the separators are proton exchange membranes or sintered glass plates , and 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 . the substrates 1 used are either carbon tubes ( images 6 a 1 , 6 a 2 and 6 a 3 ) or vitreous carbon beads ( images 6 b 1 , 6 b 2 and 6 b 3 ), the electrolytic solutions 40 are aqueous solutions which , as a source of electrodepositable material , contain the following metal salts : aucl 4 − at 1 mm ( images 6 a 2 and 6 b 2 ), or ptcl 6 2 − at 10 mm ( image 6 a 3 ), or silver nitrate agno 3 1 mm ( image 6 b 3 ). in the particular case of the use of substrates of vitreous carbon beads , the electrolytic solution 40 is a hydrogel agar . it was observed by scanning electron microscopy ( sem ) the substrates before ( images 6 a 1 and 6 b 1 ) and after synthesis by electrodeposition ( images 6 a 2 , 6 a 3 , 6 b 2 , 6 b 3 ). on fig6 a 1 to 6 a 3 and 6 b 1 to 6 b 3 , the visible scale ( white line ) is of 5 m . the results of these observations are summarized in table 1 below . synthesis of micron janus particles according to an embodiment of the invention , monofunctionnalized using the device represented on fig3 monofunctionnalized janus particles were synthesized in accordance with the method according to an embodiment of the invention by using the electrodeposition device represented on fig3 wherein : 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 , the separators are thin glass walls of 100 m and separated from each other also by 100 m ; the substrates 1 used are either 1 carbon tubes ( images 6 a 1 and 6 a 4 ) or vitreous carbon beads ( images 6 b 1 and 6 b 4 ), the electrolytic solution 40 is a hydrogel of agar , which contains , as a source of electrodepositable material , the gold chloride aucl 4 − at 10 mm ( image 6 a 4 ) and gold chloride aucl 4 − at 1 mm ( image 6 b 4 ). it was observed by scanning electron microscopy ( sem ) the substrates before ( images 6 a 1 and 6 b 1 ) and after the synthesis by electrodeposition ( images 6 a 4 and 6 b 4 ). on fig6 a 4 and 6 b 4 , the visible scale ( white line ) is also of 5 m . results of these observations are summarized in table 1 below . monofunctionnalized janus particles were synthesized in accordance with the method according to an embodiment of the invention by using the electrodeposition device represented on fig2 wherein : 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 ; the separators are proton exchange membranes or sintered glass plates ; 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 ; the substrates 1 used are vitreous carbon beads ; and the electrolytic solution 40 is a hydrogel of agar , which contains , as a source of electrodepositable material , gold chloride aucl 4 − at 10 mm . it was observed by scanning electron microscopy ( sem ) the substrates before ( images 7 a ) and after the synthesis by electrodeposition ( images 7 b ). on fig7 a and 7b , the visible scale ( black line ) is of 1 m . synthesis of micron janus particles according to embodiments of the invention , copper / polypyrrole bi - functionalized by using the device represented on fig2 : bi - functionalized copper / polypyrrole janus particles were synthesized in accordance with the method according to an embodiment of the invention by using the electrodeposition device represented on fig2 wherein : a first electrolytic solution 40 consisting of a suspension of cu i in acetonitrile at the rate of 10 mm of cu i is prepared , wherein carbon nanotubes are introduced at the rate of 0 . 1 mg into the suspension ; a second electrolytic solution 40 is prepared comprising 10 mm of cu i and 50 mm of pyrrole , a sonication of these two solutions is carried out during one minute , these two suspensions 40 are introduced into the electrodeposition cell 3 ; a potential difference of the order of 2 kv is imposed between the electrodes ; the separators are proton exchange membranes ; and the formation of a copper deposit is generated on one of the ends of the tubes by reduction of cation cu + , and the formation of a deposit of pyrrole is generated on the other side by oxidation of the pyrrole . the thus obtained dissymmetrical copper / polypyrrole carbon tubes were observed by scanning electron microscopy ( sem ): fig9 b , the visible scale ( white line ) is of 10 m . the deposits were characterized by energy dispersive analysis ( eds )( fig9 c ). synthesis of micron janus particles according to the invention copper / copper bi - functionalized using the device shown on fig2 bi - functionalized janus particles were synthesized in accordance with the method according to an embodiment of the invention by using the electrodeposition device represented on fig2 wherein : an electrolytic solution 40 consisting of a suspension of cu i in acetonitrile at the rate of 10 mm of cu i is prepared , wherein carbon nanotubes are introduced at the rate of 0 . 1 mg into the suspension ; then a sonication of this solution is carried out during one minute , it is introduced into the electrodeposition cell 3 ; a potential difference is imposed in pulsed regime with an electric field of 125 mv m − 1 in the electrodeposition cell : according to the tested pulses varying between 12 s and 30 s , variations are observed at the deposits , with a time interval between the pulses ( relaxation time ) of 1 s or 5 minutes ; the separators are proton exchange membranes ; and the formation of a copper deposit is generated on each of the ends of the tubes . the thus obtained modified bi - functionalized copper / copper carbon nanotubes were observed by optical transmission microscopy : on fig8 a to 8 d , the visible scale ( black lines ) is of 20 m . fig8 a ( with a pulse interval of 5 minutes ) and 8 b ( with a pulse interval of 10 s ) correspond to a pulse of 12 s , whereas fig8 c ( with a pulse interval of 5 minutes ) and 8 d ( with a pulse interval of 10 s ) correspond to a pulse of 30 s . the obtained particles were also observed with a scanning electron microscope ( sem ) ( fig9 a ). when the relaxation time ( time between pulse potentials where the potential is stopped ) is sufficiently long , symmetrically modified tubes ( fig8 a and 8 c ) are obtained , whereas when this time is short , the particles are only modified at one end ( fig8 b and 8 d ). the imposition time of the electric field also makes it possible to control the size of the deposit . synthesis of micron janus particles according to embodiments of the invention , monofunctionnalized , using the device represented on fig2 monofunctionnalized janus particles were synthesized in accordance with the method according to an embodiment of the invention by using the electrodeposition device represented on fig2 wherein : a potential difference e of the order of 1 kv is imposed between the electrodes , resulting in an electric field of 25 kv m − 1 in the electrodeposition cell ; the separators are sintered glass plates ; the electrodes 21 , 22 are immersed in ethanol at − 100 ° c . 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