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    • 专利摘要:
    The invention relates to a method for manufacturing a membrane (16) from an amphiphilic block copolymer (20) comprising a hydrophilic block (21) and a hydrophobic block (22). This method comprises successive steps of immersing a support (10) comprising functions capable of forming a bond with the hydrophilic block (21) in a bath (11) containing the copolymer in solution in an apolar organic solvent, during a a time sufficient to allow the formation of non-covalent bonds between the hydrophilic block (21) and the support (10) and the immobilization of a first layer of the copolymer on the surface of the support; then adding (13) water in the bath (11), so as to cause the self-assembly of a second layer of copolymer on the first layer.
    公开号:FR3061440A1
    申请号:FR1750095
    申请日:2017-01-05
    公开日:2018-07-06
    发明作者:Jean-Paul Chapel；Christophe Schatz
    申请人:Centre National de la Recherche Scientifique CNRS；Universite de Bordeaux；Institut Polytechnique de Bordeaux；
    IPC主号:
    专利说明:

    (© Agent (s): IPSIDE.
    FR 3 061 440 - A1 © PROCESS FOR THE MANUFACTURE OF A COPOLYMER MEMBRANE WITH AMPHIPHILIC BLOCKS.
    (57) The invention relates to a method for manufacturing a membrane (16) from an amphiphilic block copolymer (20) comprising a hydrophilic block (21) and a hydrophobic block (22). This method comprises successive steps of immersing a support (10) comprising functions capable of forming a bond with the hydrophilic block (21) in a bath (11) containing the copolymer in solution in an apolar organic solvent, for one sufficient time to allow the formation of non-covalent bonds between the hydrophilic block (21) and the support (10) and the immobilization of a first layer of the copolymer on the surface of the support; then the addition (13) of water to the bath (11), so as to cause the self-assembly of a second layer of copolymer on the first layer.
    MULTILAYER ON SOLID SUPPORT BASED ON

    The present invention relates to a method for manufacturing a multilayer membrane supported on a solid surface, from one or more copolymers with amphiphilic blocks. The invention also relates to a membrane capable of being obtained by such a process.
    Block copolymers are a class of materials with the ability to self-assemble at the nanoscale, which today are ideal candidates for the preparation of organized thin films. These thin films find application in fields as varied as nanolithography, synthesis of nanoparticles, optoelectronic devices, non-porous membranes, sensors, etc. It is also entirely advantageous for such films to be established on solid supports, which generally give them greater mechanical stability than that of vesicle membranes or self-supporting planar films. The solid support makes it possible in particular to preserve the structure of the film even after drying.
    The best known methods for the preparation of organic thin films are spin-coating, self-assembly of monolayers, grafting of polymers and assembly by the Langmuir-Blodgett technique.
    The Langmuir-Blodgett technique is in particular one of the most efficient techniques at present for preparing ultrafine multilayer membranes supported on a solid support, based on amphiphilic block copolymers.
    More particularly, homogeneous membranes based on copolymers with amphiphilic blocks on a solid support can be prepared by consecutively using Langmuir-Blodgett and Langmuir-Shaefer techniques. In a first step, a functionalized amphiphilic block copolymer is physically, specifically or covalently attached to a substrate by the Langmuir-Blodgett technique. Then, the substrate thus covered with the first layer of copolymer is placed on top of a Langmuir-Blodgett film and passed through an air-water interface, so as to transfer a second layer of copolymer on the first layer. This method has the advantage of good control of the density of the layers.
    However, this method is difficult to implement on an industrial scale, in particular because of the technical and economic difficulties which this implementation raises. It is also not applicable to all copolymers, nor to all types of supports, for example hollow objects. It also does not make it possible to control the nanometric orientation of the blocks of copolymer in the film.
    Other methods of preparing membranes on a solid support, based on copolymers with amphiphilic blocks, have been proposed by the prior art.
    In this regard, we can for example cite the document WO 03/008646, which describes a method of forming a monolayer coating on a substrate such as a sensor, by self-assembly of multiblock surfactant molecules comprising a hydrophilic domain and a hydrophobic domain, such as a block copolymer of ethylene oxide and propylene oxide, then covalent fixing of this monolayer on the substrate, this fixing using specific reactive groups carried by the molecules.
    Document WO 02/24792 describes a method for preparing thin films called self-assembled by soaking a substrate in a dilute solution of a self-assembling amphiphile, or exposure to a vapor phase containing the amphiphile, so that a single-layer organized molecular architecture spontaneously forms on the substrate. A film precursor is incorporated into an adhesive composition, so as to allow attachment to the substrate.
    None of these methods, however, proves satisfactory for implementation on an industrial scale on all types of surfaces, and the preparation of multilayer membranes, in particular bilayers, on a large scale, under conditions allowing the control of the organization. and functionality of the constituent layers of the membrane, remains very difficult to obtain from amphiphilic block copolymers.
    The present invention aims to remedy the drawbacks of the processes for manufacturing membranes by self-assembly of an amphiphilic block copolymer proposed by the prior art, in particular the drawbacks set out above, by proposing such a process which makes it possible to prepare a organized ultra-thin membrane, supported on a solid support, with precise control of the thickness of the membrane and of the orientation of the copolymer blocks which constitute it on a nanometric scale, this process being able to be easily implemented works on an industrial scale.
    The invention also aims to make this method applicable: to a very wide variety of solid supports, in particular from the point of view of their shape and size, in particular to supports of flat, curved, hollow, macroscopic, colloidal shape , and / or from the point of view of the material entering into their constitution; and to a very wide variety of copolymers with amphiphilic blocks, this for example whatever the mass ratio between the hydrophilic blocks and the hydrophobic blocks.
    The invention also aims to ensure that this process makes it possible to form membranes of both symmetrical and asymmetrical structure, in particular to form asymmetrical membranes composed of two different block copolymers, in order to give the membrane a high degree of functionality. .
    Additional objectives of the invention are that this process is both effective, ecological and economical to implement.
    In the present description is meant by amphiphilic block copolymer any block copolymer of which at least one block is hydrophilic and at least one block is hydrophobic.
    Within the meaning of the present invention, the expression “block copolymer” includes both block copolymers themselves, that is to say copolymers comprising blocks of different compositions connected together in linear sequences, as well as graft copolymers, in which at least one block is connected laterally to the main chain, and the composition of which is different from that of this main chain, which constitutes another block of the copolymer.
    Because of their particular structure, copolymers with amphiphilic blocks adopt specific conformations in solution, in particular a micellar conformation.
    Conventionally, the following description also means:
    - by hydrophilic block, a block of the water-soluble copolymer. The hydrophilic block can consist of a hydrophilic homopolymer, or of a random copolymer containing one or more hydrophilic monomers;
    - by hydrophobic block, a block of the copolymer which is not soluble, or poorly soluble, in water. The hydrophobic block can consist of a hydrophobic homopolymer, or a random copolymer containing one or more hydrophobic monomers.
    By asymmetric membrane is meant a membrane having on its two faces, that is to say its so-called inner face and its so-called outer face, block copolymers of different chemical nature.
    At the origin of the present invention, it has been discovered by the inventors that it is possible to prepare ultrathin membranes supported on solid support from copolymers with amphiphilic blocks, by a two-phase process, which can be implemented. in situ, the first phase of which consists in controlling / modulating the interactions between the support and one of the blocks of the copolymer in order to create a first monolayer of copolymer immobilized by strong interaction on the surface of the solid support, and the second phase consists in trigger the self-assembly of a second monolayer of copolymer on the first monolayer, by tilting the polarity of the solvent used, in order to form a bilayer membrane structure firmly immobilized on the solid support.
    Thus, it is proposed by the present inventors a process for manufacturing a membrane comprising at least two layers, from at least one amphiphilic block copolymer comprising at least one hydrophilic block and at least one hydrophobic block, known as the first copolymer with amphiphilic blocks.
    This process includes successive stages of:
    a / immersion of a support comprising functions capable of forming a bond, in particular a non-covalent bond, with the hydrophilic block of the first amphiphilic block copolymer in a first bath containing said first amphiphilic block copolymer in solution in a non-organic solvent selective for said first amphiphilic block copolymer, in which said hydrophilic block and said hydrophobic block are soluble, this for a sufficient time to allow the formation of bonds between said hydrophilic block and the support, and the immobilization of a first layer of the first amphiphilic block copolymer on the surface of the support;
    b / where appropriate, when it is intended to form a membrane of asymmetrical structure, replacement of the first bath by a second bath containing a second copolymer with amphiphilic blocks comprising at least one hydrophilic block and at least one hydrophobic block, in solution in a non-selective organic solvent for said second amphiphilic block copolymer, in which the hydrophilic block and the hydrophobic block of the second amphiphilic block copolymer are soluble;
    c / and addition of water to the bath containing the support on the surface of which said first layer is immobilized, so as to cause, by hydrophobic effect, the self-assembly of a second layer of amphiphilic block copolymer on said first layer. Depending on whether the intermediate step b / has been implemented or not, this second layer is constituted respectively by the second amphiphilic block copolymer, or by the first amphiphilic block copolymer.
    A non-selective solvent for a copolymer here designates, in a conventional manner in itself, a solvent in which all of the blocks constituting this copolymer are soluble.
    Such a method is advantageously applicable to a wide variety of amphiphilic block copolymers, and to all types of supports, these supports being able to have any shape, in particular a curved, hollow, spherical, macroscopic, or even divided shape, for example a nanoparticulate shape. , etc.
    It is also easy and inexpensive to implement, including on an industrial scale, and more environmentally friendly than the methods of the prior art. In particular, it requires little energy, the various stages preferably being carried out at ambient temperature and at atmospheric pressure. It also requires, as raw materials, only water, organic solvent, advantageously in an amount less than 1 liter per m 2 of membrane, and few copolymers with amphiphilic blocks, most generally an amount of amphiphilic block copolymers not exceeding 30 mg / m 2 of membrane. The organic solvent can also be easily recovered at the end of the process, recycled and reused.
    The different stages of the process according to the invention can also be carried out in situ. They allow the membrane to be constructed layer by layer, so that it is possible to finely control the architecture of each of the layers, in particular their thickness, the molecular orientations within them, in particular the nanometric orientation of the copolymer blocks. in the membrane, etc.
    In particular, by an adequate choice of the copolymer (s) with amphiphilic blocks, in particular of the nature (glassy or rubbery) of the hydrophobic block, of the molecular mass of the hydrophilic block and of the hydrophobic block and / or of the hydrophobicity of the hydrophobic block, and by an adequate choice of the solid support and of the solvents used, it is possible to control the adhesion of the membrane to the support, the cohesion, the thickness and the chemical affinity of the membrane, and in particular of the hydrophobic reservoir which 'it forms, as well as its surface functionalities, with a view to the subsequent interactions which it is intended to form within the framework of its application.
    In the first step a /, thanks to the nature of the solvent used, there is advantageously no self-assembly of the first amphiphilic block copolymer in the bath. The hydrophilic blocks of the copolymer molecules form bonds with the support, and spread over the surface on the surface of the latter, to form a monolayer whose characteristics can advantageously be precisely controlled by an adequate choice of operating parameters. This monolayer is immobilized on the support. The hydrophobic blocks are then exposed on the surface of this monolayer.
    The bonds formed between the hydrophilic blocks of the molecules of the first amphiphilic block copolymer and the support can be both covalent and non-covalent.
    When it is desired to obtain a symmetrical membrane, in which the two layers are of similar constitution, the intermediate step b /, replacing the first bath with a second bath containing a copolymer with different amphiphilic blocks, is not carried out. Step c / of modifying the polarity of the medium by adding water is carried out directly in the first bath.
    When it is desired to obtain an asymmetrical membrane, the first layer and the second layer of which are of different constitution, the intermediate step b / is carried out. In particular embodiments of the invention, an intermediate rinsing of the support is then carried out on the surface of which the first layer is immobilized, before its immersion in the second bath.
    In step c /, a hydrophobic interaction between the hydrophobic blocks of the copolymer molecules is generated by the controlled addition of water to the organic medium, which has the effect of modifying the polarity of this medium. This advantageously triggers, by hydrophobic effect, the self-assembly of a second layer of copolymer on the first layer already immobilized on the support, and, therefore, the formation of a bilayer membrane supported on the solid support.
    The process according to the invention thus makes it possible to form ultrathin bilayer organic membranes, of thickness which may be as low as 100 nm, and which may even be less than 20 nm.
    These membranes advantageously find application in fields as diverse as electronics; optoelectronics; microfluidics; the field of sensors, whether they are vibration, image, medical, solar thermal sensors, etc. ; photonics; photovoltaics; plasmonics; catalysis; textiles, paints and ceramics; cosmetics; pharmaceuticals, in particular for the administration of drugs, the immobilization of antigens or antibodies in the bilayer; medical diagnosis; etc.
    In such fields, the membranes obtained by a process according to the present invention can for example be used for one of their following possible functions, these functions being linked to the structure of the amphiphilic block copolymer (s) which constitute them, and more particularly the functionalities present on their surface: wetting, corrosion inhibition, anti-UV radiation, amphiphobicity, impermeability, anti-fouling, anti-dust, hydrophobic self-cleaning, lubrication, adhesion, electrical insulation or electrical conductivity, immobilization of biomolecules, membrane mimes cells, biosensor, chemosensor, ability to immobilize nanoparticles on their surface (for the preparation of plasmonic materials, catalysis), etc.
    Such functions can be imparted to the membrane by the amphiphilic block copolymer (s) themselves. For example, when the copolymer comprises a hydrophobic block of polyethylene glycol type, this block, exposed on the surface of the membrane, gives the latter a non-stick function.
    Otherwise, such functions can be provided by modification of the surface of the membrane, at the end or in the last step of the process according to the invention. Any modification method, in particular chemical, conventional in itself for those skilled in the art can be used for this purpose.
    Particular functions can also be provided to the membrane during its manufacture, by introduction into the first bath, for step a / of immersion of the support in this first bath, of one or more active agents which are then found trapped in the membrane during the self-assembly of the second layer on the first layer. The membrane then acts as a hydrophobic reservoir for active agents whose properties can advantageously be used for numerous applications. For example, it can be included in this way in the membrane of gold nanoparticles, for example for photonics / plasmonics applications.
    Each amphiphilic block copolymer used in the context of the invention may equally well be of the two-block type, that is to say a diblock copolymer, than of three blocks, that is to say a triblock copolymer (hydrophobic block - hydrophilic block - hydrophobic block, in which the hydrophobic blocks are identical or different; or hydrophilic block - hydrophobic block - hydrophilic block, in which the hydrophilic blocks are identical or different), or even more. It can have a linear, star or grafted architecture.
    By different blocks is meant both blocks of different nature and blocks of the same nature and of different molar masses.
    The architecture of the first amphiphilic block copolymer, and where appropriate that of the second amphiphilic block copolymer, is preferably of the diblock type, that is to say comprising a hydrophilic block and a hydrophobic block, or of the triblock type.
    Preferably, the copolymer (s) with amphiphilic block (s) comprises (s) a hydrophilic block relatively short compared to the hydrophobic block. For example, the copolymer (s) with amphiphilic block (s) may / may comprise a hydrophilic block with a degree of polymerization between 5 and 50, and a hydrophobic block with a degree of polymerization between 50 and 500.
    In particular embodiments of the invention, which are however in no way limitative of the latter, when the intermediate step b / is implemented, at least one hydrophobic block of the second copolymer with amphiphilic blocks is identical to the minus one hydrophobic block of the first amphiphilic block copolymer. The other blocks, both hydrophilic and hydrophobic, may be the same or different. The different amphiphilic block copolymers used can comprise the same number of blocks, or different numbers of blocks, and the same architecture, or different architectures.
    In other particular embodiments of the invention, when the intermediate step b / is implemented, the second amphiphilic block copolymer and the first amphiphilic block copolymer comprise different hydrophobic blocks.
    More generally, the first bath may contain a single copolymer with amphiphilic blocks, or several such copolymers capable of forming a bond with the solid support. The second bath can also contain a single amphiphilic block copolymer, or several such copolymers.
    The hydrophobic block of the first amphiphilic block copolymer, and if necessary of the second amphiphilic block copolymer, is for example chosen from the group consisting of polystyrenes (such as polystyrene, poly (a-methylstyrene), polyacrylates (such as polyethylacrylate, n-butyl polyacrylate, tert-butyl polyacrylate, polymethyl methacrylate, alkyl polycyanocrylate), polydienes (such as polybutadiene, polyisoprene, poly (1-4- cyclohexadiene)), polylactones (such as poly (e-caprolactone), poly (ô-valerolactone), polylactides and polyglycolides (such as poly (L-lactide), poly (D-lactide), poly (D, L3061440 lactide), polyglycolide, poly (lactide-co-glycolide)), polyolefins (such as polyethylene, poly (isobutylene)), polyoxiranes (such as polypropylene glycol, polybutylene glycol) , polysiloxanes (such as poly (dimethylsiloxane), poly (diet hylsiloxane), poly (methylsiloxane), poly (ethyl methyl siloxane), poly (ferrocenyl dimethylsilane)), polyacrylonitriles, polyvinyl acetates, poly (tetrahydrofuran), polyhydroxyalkanoates, polythiophenes, polypeptides (such as poly (y-benzyl of L-glutamate), polyvalin, polyisoleucine), and polycarbonates (such as poly (trimethylene carbonate)), such a list being in no way limitative of the invention.
    Preferably, the copolymer or amphiphilic block copolymers used in the context of the invention comprise at least one hydrophobic block of styrenic or acrylate type. Such a hydrophobic block can for example be chosen from polystyrenes such as atactic polystyrene (with polydispersity index PDI <1.2), isotactic polystyrene, syndiotactic polystyrene, poly (4-acetoxy-styrene), poly (3-bromostyrene) , poly (4-bromostyrene), poly (2chlorostyrene), poly (3-chlorostyrene), poly (4-chlorostyrene), poly (pentafluorostyrene), poly (4-dimethylsilyl-styrene), poly (4-hydroxy-styrene), poly (4-methoxy-styrene), poly (4-methyl-styrene), poly (4-t-butyl-styrene), poly (4 (tert-butoxycarbonyl) oxy-styrene), poly (3- (hexafluoro-2 -hydroxypropyl) styrene), poly (vinyl benzyl chloride), poly (4-vinyl benzoic acid), poly (4 vinyl benzoic acid, tert-butyl ester), poly (4-cyano-styrene), poly (4- [N , Nbis (trimethylsilyl-amino-methyl] styrene), poly (methyl 4-vinyl benzoate); or among polyacrylates such as poly (benzyl α-ethyl acrylate), poly (benzyl a-propyl acrylate), poly (acrylate cyclohexyl), poly (cyclohe methacrylate) xyl), poly (isopropyl acrylate), poly (ethyl methacrylate), poly (ethyl a-ethyl acrylate), poly (ethyl a-propyl acrylate), poly (glycidyl methacrylate), poly ( hydroxypropyl acrylate), poly (isobornyl methacrylate), poly (isobutyl methacrylate), poly (lauryl methacrylate), poly (methyl acrylate), poly (methyl a-bromoacrylate), poly (methacrylate N, N-dimethylaminoethyl), poly (2,2,2-trifluoroethyl methacrylate), poly (n-butyl methacrylate), poly (neopentyl methacrylate), poly (neopentyl acrylate), poly (n- methacrylate) hexyl), poly (n-nonyl acrylate), poly (n-nonyl methacrylate), poly (n-octyl acrylate), poly (n-propyl methacrylate), poly (octadecyl methacrylate), poly (methacrylate sec-butyl), poly (tert-butyl aethylacrylate), poly (a-propyl tert-Butyl acrylate), poly (tetrahydrofurfanyl methacrylate), poly (methyl 2,4-dimethylpenta-2,4-dienoate) ), poly (2- acrylate ethyl hexyl), poly (1-adamantyl methacrylate), poly (2-hydroxypropyl methacrylate), etc.
    The hydrophilic block of the first amphiphilic block copolymer, and where appropriate the hydrophilic block of the second amphiphilic block copolymer, is for example chosen from the group consisting of polyacrylic acids (such as polyacrylic acid, methacrylic polyacid, polyacrylamic acid), polyacrylamides ( such as polyacrylamide, polydimethyl acrylamide, poly (Nisopropyl acrylamide)), polyethers (such as polyethylene oxide or polyethylene glycol, poly (methyl vinyl ether)), polystyrene sulfonic acids, polyvinyl alcohols, poly (2-vinyl N- methyl pyridinium), poly (4-vinyl N-methyl pyridinium), polyamines, polypeptides (such as polylysine, polyhistidine, polyarginine, polyglutamic acid, polyaspartic acid), polyoxazolines (such as poly (2-methyl-2-oxazoline)), polysaccharides (such as chitosan, alginate, hyaluronan, carrageenan, pectin, dextran, dextran sulfate, amylose, xylan, xyloglucan, beta glucans, fucans, poly (sialic acid, cellulose oligomers), polyureas, zwitterionic polymers (such as poly (sulfobetaines) and poly (carboxybetaines)), or any of their salts, such a list being in no way limiting of the invention.
    The support used is a solid support, comprising functions capable of forming covalent or non-covalent bonds with a hydrophilic block of the first amphiphilic block copolymer used for the formation of the first layer in step a / of the process according to l 'invention. Such non-covalent bonds can be of any type. They may in particular be hydrogen bonds, electrostatic interactions, van der Waals interactions, charge transfer interactions, or even specific interactions such as interactions between the complementary bases of DNA by example.
    The support can be formed of any material that cannot be dissolved by the organic solvent (s) forming part of the first bath, and if necessary of the second bath.
    The support can for example be formed from a material chosen from ceramics, glasses, silicates, polymers, graphite and metals.
    The support can have any shape, in particular a planar shape, a dispersed shape, such as a particle shape, nanoparticle, tube, sheet, a hollow, mesoporous shape, etc.
    For example, the support may have a planar or hollow shape, preferably a planar shape, and be formed from silica, silicon, mica, gold, silver or from a polymer material such as polyethylene, polyethylene terephthalate or polymethacrylate. methyl, if necessary functionalized on the surface beforehand. It can otherwise be in the form of organic micro- or nanoparticles, for example in carbon latex or nanotubes, or inorganic, for example in silicon dioxide SiO 2 , cerium oxide CeO 2 , iron tetraoxide Fe 3 O 4 , oxide iron Fe 2 O 3 , silver, gold, etc. The process according to the invention can also use, as a solid support, bulky molecules such as dendrimers.
    The method according to the invention may include a prior step of modifying the surface of the support in order to form on its surface functions capable of forming bonds, covalent or non-covalent, with a hydrophilic block of the first copolymer with amphiphilic blocks.
    Such a surface modification can be of any conventional type in itself for the skilled person. For example, it may consist of a physical treatment such as a plasma treatment, in the adsorption of charged polymers, such as polyelectrolytes, or also in a chemical grafting introducing reactive functions of alcohol, acid, amine, silane type, thiol, etc.
    For example, the method according to the invention may comprise a prior step of aminating the surface of a silica support, by electrostatic adsorption of a polyamine, such as polylysine, poly (allylamine) or polyethyleneimine, by preferably placed at a pH below the pKa thereof. The silica support modified at the surface by amine groups can then interact with a polyacid block, for example in tetrahydrofuran, by a simple acid / base neutralization generating pairs of strongly interacting ions (-COO ', -NH 3 + ).
    Other intermolecular forces, such as hydrogen bonds, can be used to immobilize the first layer of the membrane on the solid support, for example to allow the bonding of a block (polyethylene oxide) with silanol groups formed on the surface of a silica support.
    Examples of hydrophilic block / solid support pairs which can be used in the context of the invention are, for example, without limitation: polyethylene glycol block / silica support; polyacid acrylic block / amino silica support; poly (2-vinyl N-methyl pyridinium) block / carboxylated silica support; poly (3-hexylthiophene) block / gold support.
    The organic solvent of the first bath, and where appropriate the organic solvent of the second bath, is chosen as a function of the particular amphiphilic block copolymer used in the bath, so as to ensure good solubilization of this copolymer.
    This solvent is not selective for the associated hydrophilic block copolymer, that is to say that all the blocks of the block copolymer have good solubility there.
    The organic solvent of the first bath, and if appropriate the organic solvent of the second bath, is preferably chosen from the group consisting of tetrahydrofuran, dimethylsulfoxide, dimethylformamide, dimethylacetamide, acetonitrile, dioxane, acetone, ethylene glycol, methanol, pyridine, N-methyl -2-pyrrolidone, toluene, xylene, dichloromethane, chloroform, hexafluoroisopropanol, or any of their mixtures.
    In general, in the present description, the term solvent is understood to mean both single solvents and mixtures of solvents.
    The organic solvent used in the first bath, and if necessary in the second bath, is preferably a water-miscible solvent.
    The method according to the invention can also respond to one or more of the characteristics described below, implemented in isolation or in each of their technically operative combinations.
    In particular embodiments of the invention, the method comprises, after step c / of adding water to the bath, a step d / of rinsing the support and the layers of amphiphilic block copolymer by an aqueous solution. Such a rinsing step advantageously makes it possible to remove the micelles or vesicles formed by the amphiphilic block copolymer during the implementation of the method according to the invention, which are free in the bath. During such a step, the two layers of amphiphilic block copolymer forming the membrane remain immobilized on the support.
    Preferably, the rinsing step includes the gradual replacement of the organic solvent contained in the bath with water.
    Such a replacement can in particular be carried out by introducing water in liquid form into the bath, and concomitant suction of the liquid contained in the bath above the membrane immobilized on the support, until all the organic solvent has been replaced. with water. A water / air interface is then created in the tank containing the bath, which advantageously makes it possible to avoid the destructuring of the membrane when it comes into contact with the air, when it is removed from the bath.
    The different operating parameters of this rinsing step, in particular the rate of introduction of the rinsing water into the bath, and the suction rate of the liquid, are preferably chosen, depending in particular on the volume of the bath put in work, so that the complete replacement of the organic solvent with water is carried out in a time which can range from a few minutes to a few hours.
    In particular embodiments of the invention, the rate of introduction of the rinsing water into the bath and the suction rate of the liquid are chosen such that the volume of liquid in the bath remains constant throughout the d / rinsing step.
    When all the solution has been exchanged with water, the membrane and its support are removed from the bath.
    The method according to the invention can then include a final step of drying the membrane thus obtained.
    The organic solvent removed from the bath progressively, by exchange with water, can advantageously be recovered and recycled, according to any conventional method in itself.
    Preferably, the volume of the bath for the implementation of step c / of adding water to the bath is low, while nevertheless ensuring that the support on the surface of which the first layer is immobilized is completely immersed in the bath. Such a characteristic minimizes the phenomenon of self-assembly of the amphiphilic block copolymer in solution, in favor of the self-assembly of a second layer on the first layer immobilized on the solid support.
    More particularly, for the implementation of step c / of adding water to the bath, the height of liquid above the support on the surface of which the first layer of copolymer is immobilized is preferably low, and in particular less than 5 mm, and for example around 1 mm. Such a characteristic makes it possible to minimize, on the one hand, the cost in reagents of the process, and, on the other hand, the phenomenon of self-assembly in solution.
    In particular embodiments of the invention, step c / of adding water to the bath comprises the gradual introduction of a liquid aqueous solution into said bath. Such an embodiment proves to be particularly suitable when the bath in which the support carrying the first layer of amphiphilic block copolymer is immersed contains a water-miscible solvent. It allows a gradual change of polarity of the bath.
    The aqueous solution can be water, a dilute acid solution, a dilute base solution, or an acidic or alkaline buffer. It may also contain salts.
    The method according to the invention may comprise a concomitant step of bubbling carbon dioxide into the bath, so as to drop the pH of the bath and to allow a more precise modulation of the self-assembly of the second layer on the first layer of the membrane, especially when the hydrophilic block is a polyamine.
    Preferably, the aqueous solution is added to the bath at a distance from the support, so that it reaches the first layer immobilized on the support by diffusing, and not convective. The self-assembly of the second layer on the first layer is then carried out in a pseudo-equilibrium state, so that the second layer is particularly homogeneous.
    In particular embodiments of the invention, the gradual introduction of the liquid aqueous solution into the bath, in step c /, is carried out at a rate making it possible to obtain an increase in the amount of water in the bath less than or equal to 50%, preferably less than or equal to 20% by volume, relative to the total volume of the bath, per minute. More particularly, this flow rate is chosen to be placed in thermodynamic equilibrium conditions for self-assembly, that is to say in which there is equilibrium between the copolymer molecules in solution and the assembled copolymer molecules in the second layer of the membrane. This state of equilibrium allows better structural organization of the membrane.
    The gradual introduction of the liquid aqueous solution into the bath is preferably carried out until a quantity of water in the bath of between 5 and 50%, preferably between 3 and 30%, by volume, relative to the volume is obtained. total of the bath, preferably approximately equal to 10% by volume relative to the total volume of the bath.
    It can then be implemented in step d / rinsing the membrane, as described above.
    In the particular embodiments of the invention in which step c / of adding water to the bath comprises the gradual introduction of a liquid aqueous solution into the latter, step c / d addition of water to the bath and step d / of rinsing form in practice one and the same step, during which water is added to the bath, initially in small quantity, then the proportion d is increased in the bath by triggering the concomitant suction of liquid contained in the bath.
    In alternative embodiments of the invention, particularly suitable for cases where the organic solvent used in the bath, in step c / of adding water to the bath, is a non or not very miscible with water, this step c / includes bringing the bath into contact with saturated steam.
    This contacting is preferably carried out by saturation of the atmosphere above the bath with water vapor, and preferably for a period of between 10 and 180 minutes, for example between 10 and 90 minutes.
    The water molecules then partially dissolve in the solvent, and cause a solvent / water changeover in the bath and the change of polarity of the bath, which triggers the self-assembly of the amphiphilic block copolymer present in the bath and of the amphiphilic block copolymer forming the first layer immobilized on the support (these copolymers can be identical or different).
    In particular embodiments of the invention, in step a / the support is immersed in the first bath for a period of between 10 and 180 minutes, for example for approximately 2 hours. Such a duration advantageously makes it possible to ensure the formation, in the bath, of bonds immobilizing the molecules of the first copolymer with amphiphilic blocks, more precisely by means of the hydrophilic block, on the surface of the support.
    In particular embodiments of the invention, the first bath contains the first amphiphilic block copolymer at a concentration of between 0.01 and 10 g / l, preferably between 0.1 and 1 g / l, in the organic solvent.
    Preferably, when it is used, if it is desired to form an asymmetrical membrane, the second bath contains the second copolymer with amphiphilic blocks at a concentration of between 0.01 and 10 g / l, preferably between 0.1 and 1 g / l, in the organic solvent.
    The volume of the first bath, for the implementation of step a /, is also preferably small. For example, the height of liquid above the surface of the solid support is between 1 and 5 mm.
    Step a / can also be carried out under an inert atmosphere, for example under nitrogen or argon.
    The method according to the invention, as described above, comprising the steps a / of forming the first layer on the support, if necessary b / of replacing the bath, and c / of forming the second layer by self-assembly on the first layer, allows to obtain a bilayer membrane.
    Steps a /, where appropriate b /, and where appropriate c /, can be repeated to form additional layers on the two layers already immobilized on the support, so as to obtain a multilayer membrane comprising a number of layers greater than of them. The process then comprises, before the reiteration of step a / of immersion of the support in the bath, a step of stabilization of the first bilayer formed, for example by covering this bilayer of polymer or of particles capable of protecting its surface , or by crosslinking its hydrophobic blocks, in order to avoid the dissociation of this first bilayer during its immersion in the first bath of step a / following.
    If necessary, the process can also include, before the reiteration of step a / of immersion of the support in the bath, a step of rinsing the support and / or a step of functionalization of the first bilayer, in order to introduce on its surface, functions capable of forming, in an apolar medium, covalent bonds or non-covalent interactions with the amphiphilic block copolymer intended to constitute the next layer.
    The new steps a /, b / and c / can be carried out with the same amphiphilic block copolymers as the first steps a /, b / and c /, or with different amphiphilic block copolymers.
    The steps of the method according to the invention can thus advantageously be repeated as many times as necessary to prepare the membrane comprising the total number of layers desired.
    Another aspect of the invention relates to a membrane capable of being obtained by a process according to the invention, comprising a first layer of an amphiphilic block copolymer immobilized on a support, in particular by non-covalent bonds, and a second layer of an amphiphilic block copolymer attached to the first layer by hydrophobic interaction.
    In this membrane, the surface of the second layer is more hydrophilic than the first layer immobilized on the support. Such a characteristic can in particular be verified by measurements of contact angles, according to a technique which is conventional in itself for those skilled in the art.
    The amphiphilic block copolymer of the first layer and the amphiphilic block copolymer of the second layer may be the same or different. In the latter case, they can comprise at least one identical hydrophobic block.
    The amphiphilic block copolymer (s) and the support can meet one or more of the characteristics described above with reference to the process for manufacturing a membrane according to the invention.
    The membrane has in particular a thickness less than or equal to 100 nm, for example less than or equal to 50 nm or also less than or equal to 20 nm.
    It can have two or more layers.
    The characteristics and advantages of the invention will appear more clearly in the light of the examples of implementation below, provided for illustrative purposes only and in no way limit the invention, with the support of FIGS. 1 to 5, in which:
    - Figure 1 schematically shows the different stages of manufacturing a bilayer membrane from an amphiphilic block copolymer by implementing a method according to the invention;
    FIG. 2 shows the results obtained for the analysis of a monolayer of PS-b-PAA formed in accordance with the invention on a silicon support, a) by quartz crystal microbalance with dissipation, in the form of a graph showing the amount of copolymer adsorbed Γ as a function of the concentration of copolymer in the first bath; b) by atomic force microscopy (AFM); c) in the form of a graph showing the distribution of the heights determined from the AFM analysis;
    - Figure 3 shows the results obtained for the analysis of a symmetrical bilayer of PS-b-PAA formed according to the invention on a silicon support, a) by quartz crystal microbalance with dissipation, in the form of a graph showing the amount of copolymer adsorbed Γ as a function of the reaction time; b) by atomic force microscopy (AFM); in FIG. 3a), the solid support and the layer or layers of copolymer immobilized on its surface are shown schematically, for each stage of the process and the corresponding reaction time;
    - Figure 4 shows atomic force microscopy images of a PS-b-POE monolayer formed according to the invention on a silicon support, a) 5X5 pm 2 , b) 1X1 pm 2 ;
    - And Figure 5 shows the results obtained for the analysis of an asymmetric bilayer PS-b-PAA and PS-b-POE formed according to the invention on a silicon support, a) by atomic force microscopy (AFM ); b) in the form of a graph showing the distribution of the heights determined from the AFM analysis.
    The different stages of formation on a solid support 10 of a two-layer membrane based on an amphiphilic block copolymer 20, by implementing a process in accordance with the present invention, are illustrated schematically in FIG. 1.
    In the embodiment shown in this figure, the solid support is a flat blade. The method according to the invention is advantageously applicable in a similar manner to supports of all other forms.
    The solid support 10 carries on its surface functions capable of forming bonds with the amphiphilic block copolymer 20. In the description below, we will take the example of non-covalent bonds, this being of course in no way limiting of the 'invention.
    In the first step a /, the solid support 10 is immersed in a bath 11 comprising the amphiphilic block copolymer 20 in solution in an organic solvent.
    The amphiphilic block copolymer 20 comprises at least one hydrophilic block 21 and at least one hydrophobic block 22. In the particular embodiment illustrated in FIG. 1, it is a diblock copolymer comprising a hydrophilic block and a hydrophobic block. The invention applies similarly to any other type of block copolymer, in particular, but not limited to, triblock copolymers.
    The solvent used is a solvent with a polarity lower than that of water, not selective for the copolymer, in which the two blocks are well solvated, or a mixture of solvents having such properties.
    The contacting of the solid support 10 with the bath 11 of copolymer 20, under such conditions, leads, as illustrated at 30 in FIG. 1, in step a1 /, the formation of non-covalent bonds between the solid support 10 and the hydrophilic block 21 of the copolymer. There is thus formed on the solid support 10 a monolayer formed from hydrophilic blocks 21. The hydrophobic blocks 22 extend in turn from this monolayer, probably in a comb configuration.
    Some molecules of copolymer 20 remain free in solution.
    As illustrated at 31 in FIG. 1, in the next step c / water is added to the bath 11.
    When the solvent used is a water-miscible solvent, this is carried out by progressive addition of a liquid aqueous solution to the bath 11, as indicated at 13 in FIG. 1. The addition is preferably carried out in conditions as close as possible to pseudo-equilibrium conditions. Thus, the aqueous solution is preferably added very slowly, at a rate of a few hundred microliters per minute, and in an area of the reservoir 12 containing the bath 11 and the solid support 10 distant from the latter, so as to obtain in the tank 12 a regime of almost horizontal diffusion of water.
    When the solvent used is a water immiscible solvent, the bath 11 is placed in the presence of saturated water vapor.
    Whatever the method used, this bringing the bath 11 into contact with the water results in a gradual change in the polarity of the bath, which triggers the self-assembly of a second layer of copolymer on the monolayer fixed on the support. solid 10. More precisely, the hydrophobic blocks 22 of the free copolymer molecules in the bath 11 assemble with the hydrophobic blocks 22 of the copolymer molecules constituting the monolayer fixed on the solid support 10.
    By controlling the operating parameters, it is advantageously possible to precisely control the characteristics of this second layer. In addition, it results from the progressiveness of the change in polarity of the medium, good homogeneity of the second layer.
    At the same time, micelles of copolymer 14 free in the bath 11 are also formed, but in much smaller proportions.
    At the end of the self-assembly step c /, as indicated at 32 in FIG. 1, a final rinsing step d / is carried out. This last step aims to eliminate the vesicles or micelles of copolymer 14, as well as any aggregates, in solution, by a gradual replacement of the solvent of the bath 11 with water. Thus, as indicated at 13 in FIG. 1, water is added to the reservoir 12, at the same time as a suction of the liquid contained in the latter is carried out, as indicated at 15 in FIG. 1.
    At the end of this last step, an ultrafine bilayer membrane 16, of thickness less than 50 nm, with controlled characteristics, provided with free hydrophilic functions at the surface, is obtained on the solid support 10.
    The organic solvent removed from the tank 12 can be recycled for later reuse.
    The steps described above can be repeated as many times as desired, so as to form, one after the other, successive layers of copolymer on the solid support, by successive variations in the polarity of the medium, each bilayer formed being protected before forming the next bilayer.
    The process according to the invention can be implemented in a similar manner for the formation of asymmetrical bilayer membranes, that is to say in which the two layers are formed differently from one another.
    Thus, at the end of step a1 / in which the amphiphilic block copolymer 20 is attached to the solid support 10, the bath 11 in which this solid support is immersed can be replaced, in intermediate step b /, by a bath containing a different amphiphilic block copolymer, in solution in an organic solvent in which it has a high degree of solubility. This organic solvent can be identical to or different from that used in the first bath 11.
    The following steps of the process according to the invention can then be implemented in the same way as described above, in order to obtain an asymmetrical bilayer membrane, of perfectly controlled characteristics, in particular in terms of thickness of each of the layers and orientation of blocks present on its surface.
    EXAMPLES
    Material and methods
    The silicon slides come from the company Silicon Inc. The quartz crystal blades made of silica (14 nm in diameter) with a resonance frequency of 5 MHz are used for MCQ experiments.
    The products (3-Aminopropyl) triethoxysilane (APTES, 99%), anhydrous toluene (99.9%), Ν, Ν-dimethylformamide (DMF, 99.8%), tetrahydrofuran (THF, 99.9%), dioxane (99.8%), 4- nitrobenzaldehyde (98%) and dodecane (99%) come from Sigma-Aldrich.
    The block copolymers PS (42kg / mol) -b-PAA (4.5kg / mol) and PS (42kg / mol) -b-POE (11.5kg / mol) come from Polymer Source Inc. Each of them has a polydispersity index of less than 1.1.
    Buffered aqueous solutions: 0.1 M KCI / HCl (pH 1-2), acetate buffer 0.1 M (pH 3.5-5.5), phosphate buffer 0.1 M (pH 6-7, 5), 0.1 M sodium carbonate buffer (pH 9-10), 0.1 M sodium phosphate buffer (pH 11), 0.1 M KCl / NaOH (pH 12-13) were used for the dosing in two liquids via wetting.
    Two programmable syringe pumps from Bioseb, PTFE filters with 20nm, 0.1 µm and 0.2 µm pore sizes from GE Healthcare Life Sciences and Nalgene were used. Deionized water was used to prepare the solutions.
    Determination of the grafting density of the amine functions on the surface of the silica blade
    The slides functionalized by APTES are immersed for 3 h at 50 ° C. in an absolute ethanol solution containing 0.08% vol. acetic acid and 0.05% by mass of 4-nitrobenzaldehyde. After rinsing with ethanol to remove excess 4-nitrobenzaldehyde, the slides are immersed in an aqueous solution of 0.15% acetic acid for 1 h. The concentration of 4-nitrobenzaldehyde is determined by UV-visible spectroscopy at 268 nm. This then makes it possible to determine the surface density in amine groups.
    Ellipsometry
    Ellipsometry measurements are performed between 300 and 800 nm for three different angles (65 °, 70 °, 75 °) with an ei | i) UVISEL (Horiba Scientific) someter. To establish the model, the values n = 3.86, k = 0.02 for silica and n = 1.46, k = 0 for an organic film, are used.
    Blood pressure - contact angle determination
    The wetting measurements are carried out in air using a TRACKER tensiometer (Teclis Scientific). A drop of water (volume 2 pL) is deposited using a syringe on the surface covered with the thin film. The detection of the contact angle at is carried out continuously using a CCD camera connected to the control and analysis software. This measurement is determined by modeling the shape of the drop from the Laplace equation: AP = 2y / R. Monitoring the evaporation of the drop of water over time makes it possible to determine the natural dewetting angle of the surface. The angle of advance (maximum), the angle of retreat (minimum) and the hysteresis are then determined.
    Atomic Force Microscopy (AFM)
    The measurements are carried out in intermittent contact mode, in air and at room temperature on an ICON (Bruker) instrumentation equipped with a J-type scanner with a maximum analysis surface of 100 × 100 pm 2 and a height limit of 1 pm. The images are analyzed with WsxM software.
    Quartz crystal microbalance with dissipation (QCM-D- Q-Sense Biolin Scientific)
    The kinetic monitoring of the in situ formation of a bilayer of block copolymers is carried out inside a liquid cell of a quartz microbalance. QCM (Biolin Scientific) supports covered with a layer of silica previously functionalized with an APTES monolayer are used.
    Dynamic light scattering
    The size and polydispersity of the suspensions of silica nanoparticles are determined before / after self-assembly of a bilayer of copolymer on the surface of the nanoparticles by dynamic light scattering at 90 °, by means of an ALV system equipped with in correlator ALV5000 / E.
    EXAMPLE 1 - Polystyrene-block-poly (acrylic acid) diblock copolymer
    The polystyrene-block-poly (acrylic acid) diblock copolymer, designated PS-b-PAA, of formula:
    OH comprises a hydrophobic polystyrene block of average molar mass in number Mn = 42 kg / mol greater than its critical entanglement mass (Mc = 32 kg / mol), and a hydrophilic poly (acrylic acid) block of average molar mass Mn = 4.5 kg / mol.
    The polystyrene block (PS) has a hydrophobicity characterized by an interfacial tension with water 7 ps / water = 32 mN / m, and a glass transition temperature of 100 ° C.
    The hydrophilic poly (acrylic acid) (PAA) block offers the possibility of participating in different types of bonding with the substrate (acid-base or electrostatic, chelation). In this example, the acid-base interaction is more particularly studied.
    1.1 / Preparation of the substrate
    The solid support used is a flat blade (1x2 cm 2 ) of silicon having on the surface a thin layer of native silicon oxide (silica SiO 2 ), a few nanometers thick. In order to allow the formation of non-covalent interactions between this plate and the hydrophilic block of the PAA type, a functionalization of the substrate is necessary.
    The silica blade is functionally conventional in itself, with an aminosilane (3-aminopropyltriethoxysilane APTES), in order to form on its surface a thin film comprising primary amine -NH 2 functions .
    For this purpose, the silica blade is irradiated with UV-ozone in order to obtain reactive hydroxyl groups (-OH) on the surface. The slide is then immersed for 1 h in a 2% solution by mass of
    3- aminopropyltriethoxysilane (APTES) in anhydrous toluene. The substrate is then rinsed with anhydrous toluene and placed in the oven for 1 h at 95 ° C.
    The presence of the surface amine functions is verified by contact angle measurements at different pH. The surface density of amine functions is determined by spectroscopic assay with
    4-nitrobenzaldehyde according to a method described in the literature (Ho Moon et al. Langmuir, 1996, 12, 4621-4624). A surface density of 31.4 Å 2 / molecule is obtained.
    The assay of the surface amine functions by measuring the contact angle at different pHs shows that the pKa of the amine functions is 6.5.
    1.2 / Formation of a monolayer of copolymer on the support
    The adsorption on the solid support is carried out in solution in a mixture of dimethylformamide DMF and tetrahydrofuran THF. This non-polar mixture is non-selective for the copolymer, both the hydrophilic block and the hydrophobic block having good solubility therein.
    The polystyrene-b / oc-poly (acrylic acid) copolymer having a PS block of 42,000 g / mol (DP = 404) and a PAA block of 4,500 g / mol (DP = 63) (PS403-b-PAA 6 3) is dissolved at 1 g / L in a DMF / THF mixture (80/20) (v / v). The aminated silica blade is immersed for 2 h in the copolymer solution previously filtered on a 0.1 μm membrane.
    The substrate is then rinsed with a DMF / THF mixture (80/20) (v / v) and dried for 2 days in a hood.
    A monolayer of PS-b-PAA was formed which was firmly anchored to the surface of the solid support. This monolayer is characterized by contact angle measurement, ellipsometry and AFM. The adsorption process is also followed using a quartz crystal microbalance (QCM-D), which makes it possible to determine the amount of copolymer adsorbed within the monolayer.
    It is determined that the layer of PS-b-PAA adsorbed on the solid support has a thickness of 5.8 nm, a contact angle θ Α = 91 ° and a hysteresis value Δθ = 12 °.
    The results of the analyzes carried out are shown in FIG. 2. More particularly, for the analysis of QCM-D (FIG. 2a)), the appearance of an adsorption plateau is noted from a concentration of copolymer d 'about 10 x10' 6 mol / L (0.1 g / L), with a graft density Tsat equal to about 10mg.m ' 2 . By the analysis by AFM (FIG. 2b)), the appearance of islets of PS is clearly observed following the reorganization of the chains at the passage of the good solvent / air interface. Analysis of the distribution of the heights of the islands of copolymer on the surface (FIG. 2c)) shows a thickness of the monolayer of approximately 5 nm, in agreement with the ellipsometry measurements.
    The results of the analyzes carried out show that the copolymer monolayer is homogeneous, and of thickness close to 5 nm. The formation of islands observed in AFM corresponds to a dewetting phenomenon occurring on the surface of the film when it crosses the water-air interface. From the adsorption isotherm, one can calculate a grafting density of 0.15 copolymer chain / nm 2 , which is in good agreement with a “brush” type conformation regime obtained as soon as the Interchain separation distance is less than the size of the copolymer chain itself.
    1.3 / Formation of a symmetrical bilayer by tilting of solvent
    At the end of the step of immersion of the aminated silica blade for 2 h in the previously filtered copolymer solution, as indicated above, water is added to the copolymer solution, which has an initial volume of 2 ml, to trigger self-assembly. This addition is carried out so as to obtain, above the solid support, a height of solvent of between 2 and 3 mm.
    More specifically, water is added to the copolymer solution at a flow rate of 0.3 mL / min using a syringe pump.
    After 15 min, a volume proportion of water in the bath was obtained of 49%; while maintaining the injection of water, the solution is then pumped using another syringe pump, at a flow rate of 0.3 ml / min.
    The simultaneous stages of water injection and pumping of the solution make it possible to remove the micelles / vesicles of self-assembled copolymers in solution while completely exchanging the initial organic solution with water.
    After 2 hours of simultaneous injection and aspiration, all the organic solution was exchanged with pure water. The support is removed and put to dry in a hood for 1 day. A symmetrical bilayer membrane has formed on its surface.
    The bilayer thus self-assembled is characterized by contact angle measurement and ellipsometry.
    Its thickness, measured by ellipsometry, is 11 nm, roughly twice the thickness of its first layer (5.8 nm).
    The contact angle Θα measured in air at pH = 7 is 91 ° with a hysteresis Δθ = 31 °.
    An assay in two liquids is carried out in order to demonstrate the presence of the PAA blocks at the apices and to highlight the hydrophobic effect of the PS block. It makes it possible to define a pKa of 5.53 for the carboxylic acid group on the surface.
    In addition, during the implementation of these steps, QCM-D analyzes of the solid support are carried out at regular time intervals. The bilayer finally obtained is further analyzed by AFM. The results obtained are shown in Figure 3. More particularly, Figure 3a) shows the change in the amount of copolymer adsorbed Γ as a function of time. Figure 3b) shows the image, obtained by AFM, of the self-assembled bilayer on the solid support.
    As can be seen in this figure, in the first step of the process, a monolayer forms on the amino surface of the substrate, with a density of about 10 mg.m ' 2 (which is in agreement with the isotherm of adsorption of Figure 2a)). In the second step, in which the solvent mixture is gradually replaced by water, a second monolayer is formed on the first, with a density of 10 mg.m ' 2 . The bilayer thus formed has a final density of approximately equal to 20 mg.m ' 2 , or twice the density of a monolayer. As can be seen in Figure 3b), it has a smooth surface morphology, representative of the surface covered with PAA chains, more hydrophilic than those of PS. The total thickness of the bilayer is 10 nm.
    EXAMPLE 2 - Polystyrene-block-poly (ethylene oxide) diblock copolymer
    The polystyrene-block-poly (ethylene oxide) diblock copolymer, designated PS-b-POE, of formula:
    offers the possibility of forming hydrogen bonds with the substrate.
    The copolymer used consists of a hydrophobic polystyrene block of average molecular mass in number Mn = 42 kg / mol and of a hydrophilic poly (ethylene oxide) block of average molecular mass in number Mn = 11.5 kg / mol.
    2.1 / Preparation of the substrate
    The solid support used is a flat blade (1 × 2 cm 2 ) of silicon having on the surface a thin layer of native silicon oxide (silica S1O2), a few nanometers thick. In order to allow the formation of non-covalent interactions (hydrogen bonds) between this blade and the hydrophilic block of POE type, an Ultraviolet-Ozone treatment is carried out to introduce hydroxyl groups (-OH) at the surface of the blade.
    2.2 / Formation of a monolayer of copolymer on the support
    The solvent used is toluene. This non-polar solvent is non-selective for the copolymer, both the hydrophilic block and the hydrophobic block have good solubility there.
    The polystyrene-b / oc-poly (ethylene oxide) copolymer having a PS block of 42,000 g / mol (DP = 404) and a POE block of 11,500 g / mol (DP = 261) (PS403-b-POE 2 6i) is dissolved at 1 g / L in toluene.
    The oxidized silicon wafer (SiOH) is immersed for 2 h in the copolymer solution having been previously filtered on a 0.1 μm membrane.
    The support is then rinsed with toluene and dried for 2 days in a hood.
    A monolayer of PS-b-POE was formed securely anchored to the surface of the solid support. This monolayer is characterized by contact angle measurement, ellipsometry and AFM.
    The thickness of the monolayer formed, determined by ellipsometry, is 4.49 nm. This value is in agreement with the size of the copolymer in toluene. It is relatively low, probably because the copolymer adopts a “mushroom” type conformation, because of the molar mass of the POE block, which is relatively high. Under these conditions, the PS block spreads further.
    The contact angle measured is Θα = 46.7 ° with a hysteresis ΔΘ = 13.7 Ο .
    The AFM images obtained, at different magnifications, are shown in FIG. 4. They confirm the adsorption of the POE-PS type copolymers, from the toluene solution, on the silica surface, through the hydrogen bonds formed between the POE block and the surface silanol groups. Due to the use of a POE block of relatively high molar mass, the grafting density obtained is relatively low, which is illustrated by the presence of islands of PS spaced apart from each other. The use of lower molecular weight POEs increases the grafting density of the monolayer. Thus, the grafting density can be easily adjusted by selecting a copolymer whose hydrophilic block has an adequate molar mass.
    2.3 / Formation of a symmetrical bilayer by tilting of solvent
    At the end of the step of immersion of the oxidized silica blade for 2 h in the copolymer solution, as indicated above, the self-assembly is triggered.
    To this end, the copolymer solution is brought into contact with saturated water vapor generated by a hot water tank (at around 50 ° C.) placed near the system, all under a hermetic bell so as to saturate the atmosphere above the solution with vapor.
    The system is then rinsed by injecting water while aspirating the immiscible toluene.
    After 2 hours, the support is removed and allowed to dry in a hood for 2 days.
    On the solid support, an asymmetrical self-assembled bilayer is obtained.
    EXAMPLE 3 Formation of asymmetric bilayer PS-b-PAA and PS-bPOE
    A PS-b-PAA monolayer is formed as in Example 1.2 / above. The self-assembly of this monolayer is then carried out with a second block copolymer (PS-b-POE), comprising a different hydrophilic block but a hydrophobic block identical to that of the monolayer.
    To this end, at the end of the step of immersing the aminated silica blade for 2 h in the copolymer solution, as indicated above, the DMF / THF mixture (80/20) is replaced by a polystyrene-b / oc-poly (ethylene oxide) copolymer solution having a PS block of 42,000 g / mol (DP = 404) and a POE block of 11,500 g / mol (DP = 261) (PS 4 o3-b -POE 2 6i) at 1 g / L in toluene, solvent in which the copolymer is better solubilized. Beforehand, the solid support was rinsed with the organic solvent of the first layer (DMF / THF), in order to remove the block copolymers in non-adsorbed solution.
    The self-assembly of the bilayer is then triggered by bringing the copolymer solution into contact with saturated water vapor generated by a hot water tank (at around 50 ° C) placed near the system, all under an airtight bell for 4 hours.
    The system is then rinsed by injection of water while aspirating the immiscible toluene, at injection and aspiration rates each of 0.3 mL / min.
    After 2 hours, the support is removed and allowed to dry in a hood for 2 days.
    The asymmetrical bilayer thus self-assembled is characterized by contact angle measurement, ellipsometry and AFM.
    Its macroscopic thickness measured by ellipsometry is 17 nm.
    The relatively low forward wetting angle values Θα = 82 ° and hysteresis Δθ = 22 ° are consistent with the formation of a bilayer with POE on the surface.
    As shown in the image obtained by AFM, shown in Figure 5, the bilayer has a mushroom-like structure. This is due to the presence of POE blocks on the surface of the membrane, which have a high molar mass, and which collapse when passing through the water / air interface.
    The structure, with a roughness of 2.43 nm, has holes with a maximum depth of 15.4 nm and an average thickness of objects on the surface of 8.36 nm (as shown in the height distribution graph shown in Figure 5b )).
    These data demonstrate the formation of a bilayer with an average thickness for the PS-b-POE layer of 8.36 nm and a total thickness of around 16 nm, in agreement with ellipsometric measurements.
    EXAMPLE 4 Self-assembly on the surface of nanoparticles
    The three previous examples, produced on macroscopic flat surfaces of oxidized silica (SiOH) and amino silica (-NH 2 ) are transposed onto silica nanoparticles (200 nm diameter), both in oxidized form and in amino form.
    After the addition of water, in liquid form or in vapor form depending on the organic solvents used, the particles are centrifuged, the supernatant removed and water is added to wash the particles. This procedure is repeated at least once again in order to remove all the free polymer in solution as well as the residual traces of solvent.
    The sizes of the silica nanoparticles are measured by dynamic light scattering before and after the self-assembly of the copolymer bilayer. The difference in size makes it possible to measure the thickness of the membrane formed on the surface of the particles. This is typically between 15 and 30 nm.
    权利要求:
    Claims (17)
    [1" id="c-fr-0001]
    1. Method for manufacturing a membrane (16) from at least one amphiphilic block copolymer (20), said first amphiphilic block copolymer, comprising at least one hydrophilic block (21) and at least one hydrophobic block ( 22), characterized in that it comprises successive stages of:
    a / immersion of a support (10) comprising functions capable of forming a bond with said hydrophilic block (21) in a first bath (11) containing said first copolymer with amphiphilic blocks dissolved in an organic solvent in which said hydrophilic block and said hydrophobic block are soluble, for a sufficient time to allow the formation of bonds between said hydrophilic block (21) and said support (10) and immobilization of a first layer of said first amphiphilic block copolymer on the surface of said support (10);
    b / where appropriate, replacement of said first bath (11) with a second bath containing a second amphiphilic block copolymer comprising at least one hydrophilic block and at least one hydrophobic block, in solution in an organic solvent in which the hydrophilic block and the hydrophobic block of the second amphiphilic block copolymer are soluble;
    c / and addition of water to the bath containing said support (10) at the surface of which said first layer is immobilized, so as to cause the self-assembly of a second layer of amphiphilic block copolymer on said first layer.
    [2" id="c-fr-0002]
    2. Method according to claim 1, comprising, after step c / of adding water to the bath, a step of rinsing the support (10) and layers of amphiphilic block copolymer with an aqueous solution.
    [3" id="c-fr-0003]
    3. Method according to claim 2, according to which the d / rinsing step comprises the gradual replacement of the organic solvent contained in the bath with water.
    [4" id="c-fr-0004]
    4. Method according to any one of claims 1 to 3, according to which step c / of adding water to the bath comprises the gradual introduction of a liquid aqueous solution into said bath.
    [5" id="c-fr-0005]
    5. Method according to claim 4, according to which the progressive introduction of a liquid aqueous solution into the bath is carried out at a flow rate making it possible to obtain an increase in the amount of water in the bath less than or equal to 50% by volume. , based on the total volume of the bath, per minute.
    [6" id="c-fr-0006]
    6. Method according to any one of claims 4 to 5, according to which the progressive introduction of a liquid aqueous solution into the bath is carried out until a quantity of water in the bath of between 5 and 50% is obtained. volume relative to the total volume of the bath, preferably equal to 10% by volume relative to the total volume of the bath.
    [7" id="c-fr-0007]
    7. Method according to any one of claims 1 to 3, according to which step c / of adding water to the bath comprises bringing said bath into contact with saturated water vapor.
    [8" id="c-fr-0008]
    8. The method of claim 7, wherein the contacting of the bath with saturated water vapor is carried out for a period between 10 and 180 minutes.
    [9" id="c-fr-0009]
    9. Method according to any one of claims 1 to 8, according to which in step a / the immersion of the support (10) in the first bath (11) is carried out for a period of between 10 and 180 minutes.
    [10" id="c-fr-0010]
    10. Method according to any one of claims 1 to 9, according to which the first bath (11) contains said first amphiphilic block copolymer (20) at a concentration between 0.01 and 10 g / l, preferably between 0 , 1 and 1 g / l, in said organic solvent.
    [11" id="c-fr-0011]
    11. Method according to any one of claims 1 to 10, according to which the second bath contains said second amphiphilic block copolymer at a concentration of between 0.01 and 10 g / l, preferably between 0.1 and 1 g / 1, in said organic solvent.
    [12" id="c-fr-0012]
    12. Method according to any one of claims 1 to 11, according to which the first amphiphilic block copolymer (20), and if necessary the second amphiphilic block copolymer, is a diblock copolymer or a triblock copolymer.
    [13" id="c-fr-0013]
    13. Method according to any one of claims 1 to 12, according to which the hydrophobic block (22) of the first amphiphilic block copolymer (20), and if necessary of the second amphiphilic block copolymer, is chosen from the group consisting of polystyrenes, polyacrylates, polydienes, polylactones, polylactides, polyglycolides, polyolefins, polyoxiranes, polysiloxanes, polyacrylonitriles, polyvinylacetates, polytetrahydrofuran, polyhydroxyalkanoates, polythiophenes, polypeptides and polycarbonates.
    [14" id="c-fr-0014]
    14. Method according to any one of claims 1 to 13, according to which the hydrophilic block (21) of the first amphiphilic block copolymer (20), and if necessary the hydrophilic block of the second amphiphilic block copolymer, is chosen from the group consisting of polyacrylic acids, polyacrylamides, polyethers, polystyrene sulfonic acids, polyvinyl alcohols, poly (2-vinyl N-methyl pyridinium), poly (4-vinyl N-methyl pyridinium), polyamines, polypeptides, polyoxazolines, polysaccharides, polyureas, zwitterionic polymers, or any of their salts.
    [15" id="c-fr-0015]
    15. Method according to any one of claims 1 to 14, according to which the organic solvent of the first bath (11), and where appropriate the organic solvent of the second bath, is chosen from the group consisting of tetrahydrofuran, dimethylsulfoxide, dimethylformamide, dimethylacetamide, acetonitrile, dioxane, acetone, ethylene glycol, methanol, pyridine, N-methyl-2-pyrrolidone, toluene, dichloromethane, chloroform, xylene, hexafluoroisopropanol, or any of their mixtures.
    [16" id="c-fr-0016]
    16. Method according to any one of claims 1 to 15, according to which the support (10) is formed from a material chosen from ceramics, glasses, silicates, polymers, graphite and metals.
    5
    [0017]
    17. Membrane (16) capable of being obtained by a method according to any one of claims 1 to 16, comprising a first layer of an amphiphilic block copolymer (11) immobilized on a support (10), and a second layer of an amphiphilic block copolymer attached to said first layer by hydrophobic interaction.
    1/2
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    同族专利:
    公开号 | 公开日
    JP2020505220A|2020-02-20|
    CN110300630A|2019-10-01|
    JP6963619B2|2021-11-10|
    EP3565672A1|2019-11-13|
    FR3061440B1|2021-02-12|
    US20200030750A1|2020-01-30|
    WO2018127656A1|2018-07-12|
    CN110300630B|2021-10-29|
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    优先权:
    申请号 | 申请日 | 专利标题
    FR1750095A|FR3061440B1|2017-01-05|2017-01-05|METHOD OF MANUFACTURING A MULTILAYER MEMBRANE ON A SOLID SUPPORT BASED ON AMPHIPHILIC BLOCK COPOLYMER|
    FR1750095|2017-01-05|FR1750095A| FR3061440B1|2017-01-05|2017-01-05|METHOD OF MANUFACTURING A MULTILAYER MEMBRANE ON A SOLID SUPPORT BASED ON AMPHIPHILIC BLOCK COPOLYMER|
    US16/475,815| US20200030750A1|2017-01-05|2018-01-03|Process for manufacturing a multilayer membrane on a solid support using an amphiphilic block copolymer|
    JP2019536977A| JP6963619B2|2017-01-05|2018-01-03|A method of producing a multilayer film on a solid support using an amphipathic block copolymer.|
    PCT/FR2018/050005| WO2018127656A1|2017-01-05|2018-01-03|Process for manufacturing a multilayer membrane on a solid support using an amphiphilic block copolymer|
    EP18701512.8A| EP3565672A1|2017-01-05|2018-01-03|Process for manufacturing a multilayer membrane on a solid support using an amphiphilic block copolymer|
    CN201880010263.7A| CN110300630B|2017-01-05|2018-01-03|Method for making multilayer films on solid supports using amphiphilic block copolymers|
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