Micro/nano structures of colloidal nanoparticles attached to an electret substrate and method for producing such micro/nano structures

Patent metadata

Field	Value
Publication number	US-2016009552-A1
Application number	US-201414772980-A
Country	US
Kind code	A1
Filing date	Feb 27, 2014
Priority date	Mar 8, 2013
Publication date	Jan 14, 2016
Grant date	—

Abstract

The invention relates to a method for producing a directed monolayer or multilayer assembly of colloidal nanoparticles attached to an electret substrate, including a step ( 4 ) of imparting a surface electric potential to an electret substrate according to a pattern of positive and/or negative electric charges, and a step ( 6 ) of contacting an electret substrate with a colloidal dispersion. The colloidal dispersion comprises electrically neutral or near neutral and electrically polarizable colloidal nanoparticles, and a nonpolarizing or weakly polarizing dispersion medium. The absolute value of the surface electric potential and the concentration of polarizable nanoparticles are no lower than a first surface electric potential threshold and no lower than a second concentration threshold, respectively, such as to obtain an assembly having a desired geometric shape, at least the first layer of which is compact in terms of the absence of undesired gaps having sizes greater than the size of two adjacent nanoparticles, preferably not greater than the size of one nanoparticle.

First claim

1 . A process for the manufacture of a micro/nanostructure formed of colloidal nanoparticles comprising a monolayer or multilayer assembly of colloidal nanoparticles which are attached to an electret substrate, having a freely chosen and predetermined geometric shape, at least the first layer of which is compact in terms of absence of undesired gaps with sizes of greater than or equal to the size of two adjacent nanoparticles, optionally greater than or equal to the size of one nanoparticle, comprising the stages consisting of:
in a first stage, providing an electret substrate, composed of an electret material and having a free receiving surface, then in a second stage, writing a surface electric potential on the receiving surface of the electret substrate according to a predetermined pattern of positive and/or negative electric charges corresponding to the monolayer or multilayer assembly of nanoparticles, then in a third stage, bringing the electret substrate having the receiving surface written with the surface potential according to the desired pattern of electric charges into contact with a colloidal dispersion for a contacting time which is less than or equal to fifteen minutes, wherein: the colloidal dispersion comprises electrically neutral or quasineutral colloidal particles which are electrically polarizable under the action of an external electric field and a dispersing medium, in the form of a liquid solvent or a gas which is substantially devoid of an electrical polarization action, in which the colloidal nanoparticles are dispersed, and the absolute value of the surface electric potential and the concentration of polarizable nanoparticles are respectively greater than or equal to a first surface electric potential threshold and to a second concentration threshold, the first and second thresholds each depending on the nature of the dispersing medium and on the nature of the polarizable nanoparticles, so that after the first contacting time, the micro/nanostructure obtained is a monolayer or multilayer micro/nanostructure having the desired geometric shape, at least the first layer of which is compact in terms of absence of undesired gaps with sizes greater than or equal to the size of two adjacent nanoparticles, optionally greater than or equal to the size of one nanoparticle, the nanoparticles being bonded to one another and/or to the substrate under the action of dielectrophoretic forces created from the interaction between the polarizable nanoparticles and the written surface potential.

2 . The process as claimed in claim 1 , in which:
the assembly of colloidal nanoparticles which are attached to the electret substrate, having a freely chosen and predetermined geometric shape, is a multilayer assembly, at least the first layer of which is compact, and the absolute value of the surface electric potential and the concentration of polarizable nanoparticles are respectively greater than or equal to a third surface electric potential threshold and greater than or equal to a fourth concentration threshold, the third and fourth thresholds each depending on the nature of the dispersing medium and on the nature of the polarizable nanoparticles, so that after the contacting time, the micro/nanostructure obtained is the multilayer micro/nanostructure having the desired geometric shape, at least the first layer of which is compact in terms of absence of undesired gaps with sizes of greater than or equal to the size of two adjacent nanoparticles, optionally with sizes greater than or equal to the size of one nanoparticle, the nanoparticles being bonded to one another and/or to the substrate under the action of dielectrophoretic forces created from the interaction between the neutral and electrically polarizable nanoparticles and the written surface potential.

3 . The process as claimed in claim 1 , in which:
the assembly of colloidal nanoparticles which are attached to an electret substrate, having a freely chosen and predetermined geometric shape, is a multilayer assembly of a certain number NI of layers, each of the layers of which is compact in terms of absence of undesired gaps with sizes greater than the size of two adjacent nanoparticles, optionally greater than the size of one nanoparticle, and the absolute value of the surface electric potential and the concentration of polarizable nanoparticles are respectively greater than or equal to a fifth surface electric potential threshold and to a sixth concentration threshold, the fifth and sixth thresholds each depending on the nature of the dispersing medium, on the nature of the polarizable nanoparticles and on the number of layers, so that after the contacting time, the micro/nanostructure obtained is the multilayer micro/nanostructure having the desired geometric shape, all the layers of which are compact in terms of absence of undesired gaps with a size greater than or equal to the size of two adjacent nanoparticles, optionally greater than or equal to the size of one nanoparticle, the nanoparticles being bonded to one another and/or to the substrate under the action of dielectrophoretic forces created from the interaction between the polarizable nanoparticles and the written surface potential.

4 . A process of manufacturing a binary micro/nanostructure formed of two types of colloidal nanoparticles, comprising:
a first monolayer assembly of colloidal nanoparticles of the first type, which are attached to an electret substrate, having a first freely chosen and predetermined geometric shape, and a second monolayer or multilayer assembly of colloidal nanoparticles of the second type, which are attached to an electret substrate, having a second freely chosen and predetermined geometric shape, at least the first layer of which is compact in terms of absence of undesired gaps with a size greater than or equal to the size of two adjacent nanoparticles of the second type, optionally greater than or equal to the size of one nanoparticle, wherein the process comprises the stages consisting in: in a first stage, providing an electret substrate composed of an electret material and having a free receiving surface, then in a second stage, writing, sequentially or in parallel, a surface electric potential on the receiving surface of the electret substrate according to a predetermined pattern of electric charges having a first sign and of electric charges having a second sign opposite the first, the pattern of charges being composed of a first subpattern of charges of the first sign, corresponding to the first monolayer assembly of nanoparticles of the first type, and of a second subpattern of charges of the second sign, corresponding to the second monolayer or multilayer assembly of nanoparticles of the second type, in a third stage, bringing the electret substrate having the receiving surface written with the surface potential into contact with a first colloidal dispersion for a first contacting time, the first colloidal dispersion comprising nanoparticles of the first type electrically charged according to the second sign and a first dispersing medium in the form of a liquid solvent or of a gas and the first contacting time being sufficiently long to allow the formation, on the first subpattern of charges written in the electret substrate, of the first monolayer assembly, having the desired first geometric shape, of nanoparticles of the first type bonded to the substrate under the action of electrophoretic forces created from the Coulomb interaction between the nanoparticles of the first type and the surface potential of the first subpattern of charges, then in a fourth stage, drying the electret substrate and the first assembly, together forming an intermediate micro/nanostructure of end of third stage, by removing the first dispersing medium, then in a fifth stage, bringing the dried intermed

Assignees

• Inst Nat Sciences Appliq
• Centre Nat Rech Scient
• Univ Sabatier Toulouse Iii
• Univ Toulouse 3 Paul Sabatier

Inventors

• Ressier Laurence
• Neralagatta Munikrishnaiah Sangeetha
• Moutet Pierre

Classifications

• B82Y30/00

  Nanotechnology for materials or surface science, e.g. nanocomposites · CPC title

• B82Y40/00

  Manufacture or treatment of nanostructures · CPC title

• B05D3/14

  by electrical means · CPC title

• B81C1/00373 Primary

  Selective deposition, e.g. printing or microcontact printing · CPC title

• G03G5/024

  Photoelectret layers · CPC title