Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
  • B01D67/0002—Organic membrane manufacture
  • B01D67/0006—Organic membrane manufacture by chemical reactions
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
  • B01D69/10—Supported membranes; Membrane supports
  • B01D69/108—Inorganic support material
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
  • B01D69/12—Composite membranes; Ultra-thin membranes
  • B01D69/1214—Chemically bonded layers, e.g. cross-linking
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
  • B01D69/12—Composite membranes; Ultra-thin membranes
  • B01D69/1216—Three or more layers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
  • B01D71/06—Organic material
  • B01D71/76—Macromolecular material not specifically provided for in a single one of groups B01D71/08 - B01D71/74
  • B01D71/80—Block polymers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D1/00—Processes for applying liquids or other fluent materials
  • B05D1/18—Processes for applying liquids or other fluent materials performed by dipping
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D1/00—Processes for applying liquids or other fluent materials
  • B05D1/36—Successively applying liquids or other fluent materials, e.g. without intermediate treatment
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D2401/00—Form of the coating product, e.g. solution, water dispersion, powders or the like
  • B05D2401/10—Organic solvent
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D3/00—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials
  • B05D3/10—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials by other chemical means
  • B05D3/107—Post-treatment of applied coatings

Definitions

• the present invention relates to a method of manufacturing a multilayer membrane supported on a solid surface from one or more amphiphilic block copolymers.
• the invention also relates to a membrane that can be obtained by such a method.
• Block copolymers are a class of nanoscale self-assembling materials that are currently ideal candidates for the preparation of organized thin films. These thin films find particular application for areas as diverse as nanolithography, nanoparticle synthesis, optoelectronic devices, non-porous membranes, sensors, etc. It is furthermore quite advantageous for such films to be established on solid supports, which generally give them greater mechanical stability than vesicle membranes or self-supporting flat 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, polymer grafting and assembly by the Langmuir-Blodgett technique.
• the Langmuir-Blodgett technique is in particular one of the most efficient techniques at the present time for preparing ultrafine multilayer membranes supported on a solid support, based on amphiphilic block copolymers.
• homogeneous membranes based on solid support amphiphilic block copolymers can be prepared by consecutively implementing Langmuir-Blodgett and Langmuir-Shaefer techniques.
• a functionalized amphiphilic block copolymer is attached in a physical, specific or covalently to a substrate by the Langmuir-Blodgett technique.
• the thus coated substrate of the first copolymer layer is placed over a Langmuir-Blodgett film and passed through an air-water interface, so as to transfer a second layer of copolymer to the first layer.
• This method has the advantage of good control of the density of the layers.
• WO 03/008646 describes a method of forming a monolayer coating on a substrate such as a sensor, by self-assembly of surfactant molecules with multiblock comprising a hydrophilic domain and a hydrophobic domain, such as a block copolymer of ethylene oxide and propylene oxide, and covalent attachment of this monolayer on the substrate, this fixation using specific reactive groups carried by the molecules.
• WO 02/24792 describes a method for the preparation of so-called self-assembled thin films by dipping a substrate in a dilute solution of a self-assembling amphiphile, or exposure to a vapor phase containing the amphiphile, so that a monolayer organized molecular architecture is formed spontaneously on the substrate.
• a precursor of the film is incorporated in an adhesive composition, so as to allow attachment to the substrate.
• US 2014/099445 discloses a method of preparation on a substrate of a nanostructured film at the surface from an amphiphilic block copolymer, by contacting a solution of the copolymer in an organic solvent, where appropriate with the addition of water, and depositing this solution on the substrate in an atmosphere of high humidity.
• the present invention aims to overcome the drawbacks of membrane manufacturing processes by self-assembly of an amphiphilic block copolymer proposed by the prior art, in particular to the disadvantages described above, by proposing such a process which makes it possible to prepare a an ultra-thin organized membrane, supported on a solid support, with precise control of the thickness of the membrane and the orientation of the copolymer blocks which constitute it at the nanoscale, this process being furthermore easily work on an industrial scale.
• the invention also aims to ensure that this method is applicable to: a very wide variety of solid supports, in particular from the point of view of their shape and their 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 amphiphilic block copolymers, this for example regardless of the mass ratio between the hydrophilic blocks and the hydrophobic blocks.
• the invention further aims that this method makes it possible to form membranes of symmetrical as well as asymmetrical structure, in particular to form asymmetric membranes composed of two different block copolymers, in order to confer on the membrane a high degree of functionality. . Additional objectives of the invention are that this method is both effective, ecological and economical to implement.
• amphiphilic block copolymer is understood to mean any block copolymer of which at least one block is hydrophilic and at least one block is hydrophobic.
• block copolymer encompasses both block copolymers per se, ie copolymers comprising blocks of different compositions connected to one another in linear sequences, as well as copolymers grafted, in which at least one block is connected laterally to the main chain, and whose composition is different from that of this main chain, which constitutes another block of the copolymer.
• amphiphilic block copolymers adopt specific conformations in solution, in particular a micellar conformation.
• Hydrophilic block a block of the water-soluble copolymer.
• the hydrophilic block may consist of a hydrophilic homopolymer, or a random copolymer containing one or more hydrophilic monomers;
• Hydrophobic block a block of the copolymer insoluble or poorly soluble in water.
• the hydrophobic block may consist of a hydrophobic homopolymer, or a random copolymer containing one or more hydrophobic monomers.
• asymmetric membrane is meant a membrane having, on its two faces, ie its so-called inner face and its so-called outer face, block copolymers of a different chemical nature.
• a process for producing a membrane comprising at least two layers, starting from at least one amphiphilic block copolymer comprising at least one hydrophilic block and at least one hydrophobic block, said first copolymer with amphiphilic blocks.
• This method comprises successive steps 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 block copolymer amphiphilic solution in a non-selective organic solvent for said first amphiphilic block copolymer, wherein said hydrophilic block and said hydrophobic block are soluble, for a time sufficient to allow the formation of bonds between said hydrophilic block and the support, and immobilizing 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 diaphragm of asymmetric structure, replacing the first bath with a second bath containing a second amphiphilic block copolymer comprising at least one hydrophilic block and at least one hydrophobic block, dissolved in a non-selective organic solvent for said second amphiphilic block copoly
• a nonselective solvent for a copolymer here means, in a conventional manner in itself, a solvent in which all 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, porous and / or divided shape, for example a nanoparticulate form, or a colloidal form, etc.
• the process according to the invention is particularly applicable with success to any amphiphilic block copolymer which forms micelles in aqueous solution.
• the different steps of the process according to the invention can also be carried out in situ. They allow the construction of the membrane 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.
• amphiphilic block copolymer or copolymers in particular the nature (glassy or rubbery) of the hydrophobic block, the molecular weight of the hydrophilic block and the hydrophobic block and / or the hydrophobicity of the hydrophobic block, and by a suitable choice of the solid support and 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, for subsequent interactions that it is intended to form as part of its application.
• the first step a / due 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 of the latter, to form a monolayer whose characteristics can advantageously be accurately controlled by an appropriate 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 may be both covalent and non-covalent.
• the intermediate step b / replacing the first bath with a second bath containing a different amphiphilic block copolymer, is not performed.
• the step of modifying the polarity of the medium by the addition of water is carried out directly in the first bath.
• the intermediate step b / is carried out.
• an intermediate rinsing of the support is carried out on the surface of which the first layer is immobilized before it is immersed in the second bath.
• step c1 a hydrophobic interaction between the hydrophobic blocks of the copolymer molecules is generated by the controlled addition of water into 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, as a result, the formation of a bilayer membrane supported on the solid support.
• the process according to the invention thus makes it possible to form ultrathin organic bilayer membranes, which thickness may be as low as 100 nm and may even be less than 20 nm.
• the process according to the invention makes it possible to form bilayer membranes with a thickness of between 5 and 30 nm.
• membranes advantageously find application in fields as diverse as electronics; optoelectronics; microfluidics; the field of sensors, whether they are vibration sensors, images, medical, solar thermal, etc. ; photonics; photovoltaics; plasmonic; catalysis; the field of 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.
• the membranes obtained by a process according to the present invention may for example be used for one of their following possible functions, these functions being related to the structure of the amphiphilic block copolymer or copolymers which constitute them, and more particularly functionalities present on their surface: wetting, inhibition of corrosion, anti-UV radiation, amphiphobicity, impermeability, anti-fouling, anti-dust, hydrophobic self-cleaning, lubrication, adhesion, electrical insulation or electrical conductivity, immobilization of biomolecules, membrane mimics cell, biosensor, chemosensor, ability to immobilize nanoparticles on their surface (for the preparation of plasmonic materials, catalysis), etc.
• amphiphilic block copolymer per se.
• the copolymer comprises a hydrophobic block of polyethylene glycol type
• this block exposed on the surface of the membrane, gives the latter an anti-adhesion function.
• Particular functions may 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 trapped in the membrane during 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 many applications.
• active agents whose properties can advantageously be used for many applications.
• it can be included in this way in the membrane of fragrances, essential oils, nanoparticles such as gold nanoparticles, for example for applications in photonic / plasmonic.
• Each amphiphilic block copolymer used in the context of the invention can be both of the two-block type, that is to say a diblock copolymer, or of three blocks, that is to say one 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 present a linear architecture, star or grafted. 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 triblock type.
• the amphiphilic block copolymer (s) comprises (s) a relatively short hydrophilic block with respect to the hydrophobic block.
• the amphiphilic block copolymer (s) may comprise a hydrophilic block with a degree of polymerization of between 5 and 50, and a hydrophobic block with a degree of polymerization of between 50 and 500.
• At least one hydrophobic block of the second amphiphilic block copolymer 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 may comprise the same number of blocks, or different numbers of blocks, and the same architecture, or different architectures.
• the second amphiphilic block copolymer and the first amphiphilic block copolymer comprise different hydrophobic blocks.
• the first bath may contain a single amphiphilic block copolymer, or several such copolymers capable of forming a bond with the solid support.
• the second bath may also contain a single amphiphilic block copolymer, or several such copolymers.
• the hydrophobic block of the first amphiphilic block copolymer, and optionally the second amphiphilic block copolymer is for example chosen from the group consisting of the following hydrophobic substances: hydrophobic polystyrenes, in particular unsubstituted polystyrenes or polystyrenes substituted by a alkyl groups (such as polystyrene, poly ( ⁇ -methylstyrene), polyacrylates (such as polyethyl acrylate, n-butyl polyacrylate, tert-butyl polyacrylate, polymethyl methacrylate, polycyanocrylate); alkyl), polydienes (such as polybutadiene, polyisoprene, poly (1-4-cyclohexadiene)), polylactones (such as poly ( ⁇ -caprolactone), poly ( ⁇ -valerolactone), polylactides and polyglycolides (such as poly (L-lactide), poly (D-lactide), poly (D
• the amphiphilic block copolymer or copolymers used in the context of the invention comprise at least one hydrophobic block of styrene or acrylate type.
• a hydrophobic block may for example be chosen from hydrophobic polystyrenes such as atactic polystyrene (PDI ⁇ 1, 2 polydispersity index), isotactic polystyrene, syndiotactic polystyrene, poly (4-acetoxy-styrene), poly (3-bromostyrene) poly (4-bromostyrene), poly (2-chlorostyrene), 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-sty
• the hydrophilic block of the first amphiphilic block copolymer, and optionally the hydrophilic block of the second amphiphilic block copolymer is for example selected from the group consisting of the following hydrophilic substances: acrylic polyacids (such as polyacrylic acid, polyacrylic acid, polyacid ethylacrylic), polyacrylamides (such as polyacrylamide, polydimethyl acrylamide, poly (N-isopropyl acrylamide)), polyethers (such as polyethylene oxide or polyethylene glycol, poly (methyl vinyl ether)), polystyrenesulfonic acids, polyvinyl alcohols, poly (2-vinyl N-methyl pyridinium), poly (4-vinyl N-methyl pyridinium), polyamines, hydrophilic polypeptides (such as polylysine, polyhistidine, polyarginine, polyglutamic acid, polyaspartic acid), polyoxazolines (such as poly (2-methyl-2-oxazoline)), polysacchari
• 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 the invention. 'invention.
• Such non-covalent bonds may be of any type. It can in particular be hydrogen bonds, electrostatic interactions, van der Waals interactions, charge transfer interactions, or specific interactions such as interactions between the bases complementary to the DNA by example.
• the support may be formed of any material that can not be dissolved by the organic solvent or solvents used in the constitution of the first bath, and if necessary the second bath.
• the support may for example be formed of a material selected from ceramics, glasses, silicates, polymers, graphite and metals.
• the support may have any shape, especially a flat shape, a dispersed form, such as a particle shape, nanoparticle, tube, sheet, a hollow form, mesoporous, etc.
• the support may have a planar or hollow shape, preferably a planar shape, and be formed of silica, silicon, mica, gold, silver or a polymeric material such as polyethylene, polyethylene terephthalate or polymethacrylate of methyl, where appropriate functionalized on the surface beforehand.
• the method according to the invention can also implement, as a solid support, bulky molecules such as dendrimers.
• the method according to the invention may comprise a preliminary step of modifying the surface of the support in order to form on its surface functional groups capable of forming bonds, covalent or non-covalent, with a hydrophilic block of the first amphiphilic block copolymer.
• Such a surface modification can be of any type conventional in itself for the skilled person.
• it may consist of a physical treatment such as a plasma treatment, adsorption of charged polymers, such as polyelectrolytes, or chemical grafting introducing reactive functions of alcohol, acid, amine, silane type, thiol, etc.
• the method according to the invention may comprise a step prior to amination of the surface of a silica support, by electrostatic adsorption of a polyamine, such as polylysine, poly (allylamine) or polyethyleneimine, preferably at a pH lower than the pKa thereof this.
• the surface-modified silica support with amino groups can then interact with a polyacid block, for example in tetrahydrofuran, by a simple neutralization acid / base generating pairs of ions with strong interaction (-COO " , -NH 3 + ).
• intermolecular forces such as hydrogen bonds
• a block polyethylene oxide
• silanol groups formed on the surface of a silica support can be implemented for the immobilization of 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.
• hydrophilic block / solid support couples that may be used in the context of the invention are, for example, but not limited to: polyethylene glycol block / silica support; acrylic polyacide 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 optionally the organic solvent of the second bath is chosen according to the particular amphiphilic block copolymer used in the bath, so as to ensure good solubilization of this copolymer.
• the organic solvent of the first bath is preferably selected 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.
• solvent is intended to mean both single solvents and solvent mixtures.
• the organic solvent used in the first bath, and if necessary in the second bath is preferably a solvent miscible with water.
• the first bath, and if necessary the second bath are of course free of water.
• the method according to the invention may furthermore meet one or more of the characteristics described below, implemented individually or in each of their technically operating combinations.
• the method comprises, after the step of adding water to the bath, said addition of water causing the self-assembly according to a controlled architecture of a second layer of amphiphilic block copolymer on said first layer, a step d / of rinsing the support and amphiphilic block copolymer layers with an aqueous solution.
• a rinsing step advantageously makes it possible to eliminate the micelles or vesicles formed by the amphiphilic block copolymer during the implementation of the process according to the invention, which are free in the bath.
• the two layers of amphiphilic block copolymer forming the membrane remain immobilized on the support.
• the d / rinse step comprises the progressive 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 the entire organic solvent has been replaced. by water. It is then created in the reservoir containing the bath a water / air interface, which advantageously avoids the destructuration of the membrane when it comes into contact with the air, when it is withdrawn from the bath.
• the various operating parameters of this rinsing step in particular the rate of introduction of the rinsing water into the bath, and the suction flow rate of the liquid, are preferably chosen, depending in particular on the volume of the bath set. in such a way that the complete replacement of the organic solvent with water is carried out in a time ranging from a few minutes to a few hours.
• the rate of introduction of the rinsing water into the bath and the suction rate of the liquid are chosen so that the volume of liquid in the bath remains constant. during the entire d / rinse step.
• the method according to the invention may then, optionally, include a final step of drying the membrane thus obtained.
• the organic solvent that is removed from the bath gradually, by exchange with water, can advantageously be recovered and recycled, according to any conventional method in itself.
• the volume of the bath for the implementation of the step of adding water to the bath is low, while ensuring however that the support on the surface of which is immobilized the first layer is fully immersed in the bath .
• Such a feature 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.
• the liquid height above the support on the surface of which is immobilized the first layer of copolymer is preferably low, and especially lower at 5 mm, and for example about 1 mm.
• Such a feature makes it possible to minimize, on the one hand, the cost of process reagents, and, on the other hand, the phenomenon of self-assembly. in solution.
• the step of adding water to the bath comprises the gradual introduction of a liquid aqueous solution into said bath.
• a liquid aqueous solution into said bath.
• the aqueous solution may be water, a dilute acid solution, a dilute base solution, or an acidic or alkaline buffer. It may further contain salts.
• the process according to the invention may comprise a concomitant step of bubbling carbon dioxide in the bath, so as to reduce the pH of the bath and to allow a finer modulation of the self-assembly of the second layer on the first layer of the membrane, particularly when the hydrophilic block is a polyamine.
• the aqueous solution is added to the bath away from the support, so that it reaches the first layer immobilized on the support by diffusing, and not convectively.
• the self-assembly of the second layer on the first layer is then carried out in a state of pseudo-equilibrium, so that the second layer is particularly homogeneous.
• the gradual introduction of the liquid aqueous solution into the bath, in step c1 is carried out at a rate which makes it possible to obtain an increase in the amount of water in the bath.
• 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.
• this flow rate is chosen to be placed under conditions of thermodynamic equilibrium for self-assembly, that is to say in which there is equilibrium between the copolymer molecules in solution and the copolymer molecules assembled in the second layer of the membrane. This state of equilibrium makes it possible to obtain a better structural organization of the membrane.
• the gradual introduction of the aqueous liquid 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 bath, preferably approximately equal to 10% by volume relative to the total volume of the bath.
• the step of adding water to the bath comprises the gradual introduction of a liquid aqueous solution into the latter
• the addition step d The water in the bath and the rinsing step form in practice a single stage, during which water is added to the bath, initially in a small quantity, and then the proportion of water is increased. in the bath by triggering the concomitant suction of liquid contained in the bath.
• this step cl includes contacting the bath with saturating steam.
• This contacting is preferably carried out by saturation of the atmosphere above the bath with steam, and preferably for a period of between 10 and 180 minutes, for example between 10 and 90 minutes.
• the water molecules then partially solubilize in the solvent, and cause a solvent / water changeover in the bath and the change in polarity of the bath, which triggers the self-assembly of the amphiphilic block copolymer present in the bath and the amphiphilic block copolymer forming the first layer immobilized on the support (these copolymers may be identical or different).
• step a / the immersion of the support in the first bath is carried out for a period of between 10 and 180 minutes, for example for about 2 hours.
• a time advantageously makes it possible to ensure the formation, in the bath, of bonds immobilizing the molecules of the first amphiphilic block copolymer, more specifically via the hydrophilic block, on the surface of the support.
• 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.
• the second bath contains the second 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.
• the volume of the first bath for the implementation of step a /, is also preferably low.
• the height of liquid above the surface of the solid support is between 1 and 5 mm.
• Step a / may also be carried out under an inert atmosphere, for example under nitrogen or argon.
• the method according to the invention comprising the steps a / of forming the first layer on the support, where appropriate b / replacement of the bath, and cl formation of the second layer by self-assembly on the first layer, provides a bilayer membrane.
• the steps a /, where appropriate b /, and if necessary cl, can be repeated to form additional layers on the two layers already immobilized on the support, so as to obtain a multilayer membrane having a number of layers greater than two.
• the process then comprises, before the repetition of step a / immersion of the support in the bath, a stabilization step of the first bilayer formed, for example by covering this bilayer of polymer or particles able to protect its surface or by crosslinking its hydrophobic blocks, in order to avoid dissociation of this first bilayer during its immersion in the first bath of step a / following.
• the process may also comprise, before the reiteration of step a / of immersing the support in the bath, a step of rinsing the support and / or a step of functionalizing 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 following layer.
• the new steps a /, b / and cl can be carried out with the same amphiphilic block copolymers as the first stages a /, b / and cl, or with different amphiphilic block copolymers.
• Another aspect of the invention relates to a membrane that can be obtained by a method according to the invention.
• This membrane which is structured in its thickness itself, comprises a first layer of an immobilized amphiphilic block copolymer, in particular by non-covalent bonds, and a second layer of an amphiphilic block copolymer attached to the first layer. by hydrophobic interaction.
• 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 contact angle measurements, according to a technique that is conventional in itself for a person 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 may comprise at least one identical hydrophobic block.
• amphiphilic block copolymer or copolymers and the support may 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 even less than or equal to 20 nm. It has for example a thickness of between 5 and 30 nm. This thickness is controllable, and directly related to the size of the blocks or amphiphilic block copolymers that make up the membrane, these blocks being arranged relative to each other in an organized manner.
• It can have two or more layers.
• FIG. 1 schematically shows the different steps 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 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 adsorbed copolymer ⁇ as a function of the copolymer concentration in the first bath; (b) atomic force microscopy (AFM); c) in the form of a graph showing the distribution of heights determined from the AFM analysis;
• AFM atomic force microscopy
• FIG. 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 adsorbed copolymer ⁇ as a function of the reaction time; (b) atomic force microscopy (AFM); in Figure 3a), are shown schematically the solid support and the copolymer layer (s) immobilized on its surface, for each step of the process and the corresponding reaction time;
• AFM atomic force microscopy
• FIG. 4 shows atomic force microscopy images of a PS-b-POE monolayer formed according to the invention on a silicon support, a) 5 ⁇ 5 ⁇ 2 , b) 1 ⁇ 1 ⁇ 2 ;
• FIG. 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;
• AFM atomic force microscopy
• FIG. 6 schematically represents a bilayer membrane encapsulating nanoparticles, obtained from an amphiphilic block copolymer by implementing a method according to the invention
• FIG. 7 shows spectra obtained by UV-visible transmission spectroscopy, respectively for a bilayer membrane encapsulating gold nanoparticles obtained by a process according to the present invention (continuous curve) and for gold nanoparticles in solution. in a mixture of tetrahydrofuran and dimethylformamide (dotted line).
• FIG. 1 The different stages of formation on a solid support of a bilayer membrane based on an amphiphilic block copolymer 20, by implementing a method according to the present invention, are illustrated schematically in FIG.
• the solid support is a plane blade.
• the method according to the invention is advantageously applicable in a manner similar to the supports of all other forms.
• the solid support 10 carries on its surface functions capable of forming In the following description, non-covalent bonds will be used, this being of course in no way limiting of the invention.
• a / the solid support 10 is immersed in a bath 1 1 comprising the amphiphilic block copolymer 20 in solution in an organic solvent.
• the amphiphilic block copolymer comprises at least one hydrophilic block and at least one hydrophobic block.
• it is a diblock copolymer comprising a hydrophilic block and a hydrophilic block. hydrophobic block.
• the invention applies in a manner similar to any other type of block copolymer, including, but not limited to, triblock copolymers.
• the solvent used is a solvent of polarity lower than that of water, non-selective for the copolymer, in which the two blocks are well solvated, or a mixture of solvents having such properties.
• step a1 / the formation of non-covalent bonds between the solid support 10 and the hydrophilic block 21 of the copolymer. It thus forms on the solid support 10 a monolayer formed of hydrophilic blocks 21. Hydrophobic blocks 22 extend from this monolayer, presumably in a comb configuration.
• the solvent used is a water-miscible solvent
• this is achieved by gradually adding a liquid aqueous solution to the bath 11, as indicated at 13 in FIG.
• the addition is preferably carried out under conditions as close as possible to pseudo-equilibrium conditions.
• the aqueous solution is preferably added very slowly, at a speed of a few hundred microliters per minute, and in a zone of the reservoir 12 containing the bath 1 1 and the solid support 10 remote from the latter, so as to obtain in the reservoir 12 a quasi-horizontal water distribution regime.
• the solvent used is a solvent which is immiscible with water
• the bath 11 is placed in the presence of saturating steam.
• this bringing the bath 1 into contact with the water causes 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 bath. 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.
• a final rinsing step d1 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 progressive replacement of the solvent of the bath 1 1 with water.
• water is added to the tank 12, at the same time as suction of the liquid contained therein is carried out, as indicated at 15 in FIG.
• an ultrafine bilayer membrane 16 of thickness less than 50 nm, and controlled characteristics, provided with free surface hydrophilic functions, is obtained on the solid support 10.
• the organic solvent removed from the tank 12 can be recycled in order to its subsequent 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 of the polarity of the medium, each bilayer formed being protected before forming the next bilayer.
• the method according to the invention can be implemented in a similar manner for the formation of asymmetric bilayer membranes, that is to say in which the two layers are formed differently from each other.
• 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 may be identical to or different from that used in the first bath 1 1.
• Silicon slides are from Silicon Inc. Quartz crystal silica slides (14 nm diameter) with a 5 MHz resonance frequency are used for MCQ experiments.
• PS (42kg / mol) -b-PAA (4.5kg / mol) and PS (42kg / mol) -b-POE (1 1, 5kg / mol) block copolymers come from Polymer Source Inc. Each of they have a polydispersity index of less than 1.1.
• Buffered aqueous solutions 0.1 M KCl / HCl (pH 1-2), 0.1 M acetate buffer (pH 3.5-5.5), 0.1 M phosphate buffer (pH 6-7, 5), 0.1 M sodium carbonate buffer (pH 9-10), 0.1 M sodium phosphate buffer (pH 1 1), 0.1 M KCl / NaOH (pH 12-13) were used to dosing in two liquids via wetting.
• Slides functionalized by the APTES are immersed for 3 h at 50 ° C. in an absolute ethanol solution containing 0.08% vol. of acetic acid and 0.05% by weight of 4-nitrobenzaldehyde. After rinsing with ethanol to remove excess 4-nitrobenzaldehyde, the slides are immersed in a 0.15% aqueous acetic acid solution 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 amino groups.
• the measurements are carried out in intermittent contact mode, in air and at ambient temperature on an ICON (Bruker) instrumentation equipped with a J-type scanner with a maximum analysis area of 100 ⁇ 100 ⁇ 2 and a limit height of 13 ⁇ . Images are analyzed with WsxM software.
• the kinetic monitoring of in-situ formation of a bilayer of block copolymers is carried out inside a liquid cell of a quartz microbalance.
• QCM supports (Biolin Scientific) coated with a silica layer previously functionalized with an APTES monolayer are used.
• the size and polydispersity of the silica nanoparticle suspensions are determined before / after self-assembly of a copolymer bilayer on the surface of the nanoparticles by dynamic light scattering at 90 °, by means of an ALV system equipped with an ALV-5000 / E correlator.
• EXAMPLE 1 Diblock Polystyrene-Block-Poly (Acrylic Acid) Copolymer
• the hydrophilic poly (acrylic acid) block (PAA) offers the possibility of participating in different types of substrate binding (acid-base or electrostatic, chelation). In this example, the acid-base interaction is more particularly studied.
• the solid support used is a flat (1 ⁇ 2 cm 2 ) silicon film having on the surface a thin layer of silicon oxide (SiO 2 silica) native, a few nanometers thick .
• SiO 2 silica silicon oxide
• functionalization of the substrate is necessary.
• the silica slide is conventionally functionalized in itself, by an aminosilane (3-aminopropyltriethoxysilane APTES), in order to form on its surface a thin film comprising primary amine functional groups -NH 2 .
• the silica plate is irradiated with UV-ozone in order to obtain reactive hydroxyl groups (-OH) at the surface.
• the slide is then immersed for 1 hour in a 2% by weight solution of 3-aminopropyltriethoxysilane (APTES) in anhydrous toluene.
• APTES 3-aminopropyltriethoxysilane
• the substrate is then rinsed with anhydrous toluene and put in an oven for 1 h at 95 ° C.
• the presence of the surface amine functions is verified by contact angle measurements at different pH's.
• the surface density of amino 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 to 2 / molecule is obtained.
• the measurement of the surface amine functions by measurement of contact angle at different pHs shows that the pKa of the amine functions is -6.5. 1 .21 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 apolar mixture is non-selective for the copolymer, both the hydrophilic block and the hydrophobic block having a good solubility.
• the aminated silica slide is immersed for 2 hours in the copolymer solution previously filtered on a membrane of 0.1 ⁇ .
• the substrate is then rinsed with a DM F / THF mixture (80/20) (v / v) and dried for 2 days under a hood.
• the results of the analyzes carried out show that the monolayer of copolymer is homogeneous, and of thickness close to 5 nm.
• the formation of islets observed in AFM corresponds to a dewetting phenomenon occurring on the surface of the film as it passes through the water-air interface. From the adsorption isotherm, a graft density of 0.1 copolymer chain / nm 2 can be calculated, which is in good agreement with a "brush" type conformation regime obtained as long as the interchain separation distance is smaller than the size of the copolymer chain itself.
• water is added to the copolymer solution, which has an initial volume of 2 ml, in order to trigger the self-assembly. This addition is carried out so as to obtain, above the solid support, a solvent height of between 2 and 3 mm. Specifically, water is added to the copolymer solution at a rate of 0.3 mL / min using a syringe pump.
• the bilayer thus self-assembled is characterized by measurement of contact angle and ellipsometry. Its thickness measured by ellipsometry is 11 nm, which is approximately twice the thickness of its first layer (5.8 nm).
• FIG. 3 More particularly, FIG. 3a) shows the evolution of the amount of adsorbed copolymer ⁇ as a function of time.
• Figure 3b) shows the image, obtained by AFM, of the self-assembled bilayer on the solid support.
• a monolayer is formed on the amino surface of the substrate, with a density of about 10 mg.m- 2 (which is consistent with the isothermal)
• 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 20 mg.m -2 , 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.
• PS-b-POE The diblock polystyrene-block-poly (ethylene oxide) copolymer, designated PS-b-POE, of formulas
• the solid support used is a flat plate (1 ⁇ 2 cm 2 ) of silicon having on the surface a thin layer of silicon oxide (SiO 2 silica) native, a few nanometers thick.
• an ultraviolet-ozone treatment is carried out to introduce hydroxyl groups (-OH) on the surface of the membrane. blade.
• the solvent used is toluene.
• This apolar solvent is non-selective for the copolymer, both the hydrophilic block and the hydrophobic block have a good solubility therein.
• the oxidized silicon (SiOH) plate is immersed for 2 hours in the copolymer solution having previously been filtered through a membrane of 0.1 ⁇ .
• the support is then rinsed with toluene and dried for 2 days under a hood.
• a monolayer of PS-b-POE formed solidly on the surface of the solid support.
• This monolayer is characterized by measurement of contact angle, 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" conformation, because of the relatively high molar mass of the POE block. Under these conditions, the PS block spreads further.
• the AFM images obtained, at different magnifications, are shown in FIG. 4. They confirm the adsorption of the POE-PS copolymers, from the toluene solution, on the silica surface, through the hydrogen bonds formed between the POE block and silanol surface groups. Due to the use of a POE block of relatively high molar mass, the graft density obtained is relatively low, which is illustrated by the presence of PS islands spaced apart from each other. The use of POE of lower molecular weight makes it possible to increase the graft density of the monolayer. Thus, the graft density can be easily adjusted by selecting a copolymer whose hydrophilic block has an adequate molecular weight.
• the copolymer solution is brought into contact with saturating steam generated by a hot water tank (at about 50 ° C.) placed near the system, all under a hermetic bell so that Saturate the atmosphere above the solution with steam.
• a hot water tank at about 50 ° C.
• the system is then rinsed by water injection while sucking the immiscible toluene. After 2 hours, the support is removed and dried in a hood for 2 days. On the solid support, a self-assembled asymmetric bilayer is obtained.
• 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.
• PS-b-POE block copolymer
• the DMF / THF mixture 80/20
• the solid support was rinsed with the organic solvent of the first layer (DMF / THF) in order to evacuate the non-adsorbed solution block copolymers.
• the self-assembly of the bilayer is then triggered by placing the copolymer solution in contact with saturating steam generated by a hot water tank (at about 50 ° C.) placed near the system. all under a hermetic bell for 4 hours.
• the system is then rinsed by injection of water while sucking the immiscible toluene at injection and suction rates each of 0.3 mL / min. After 2 hours, the support is removed and dried in a hood for 2 days.
• the asymmetric bilayer thus self-assembled is characterized by measurement of contact angle, ellipsometry and AFM. Its macroscopic thickness measured by ellipsometry is 17 nm.
• the bilayer has a mushroom structure. This is due to the presence of POE blocks on the surface of the membrane, which have a high molar mass, and collapse as they pass through the water / air interface.
• the structure 2.33 nm in roughness, has holes with a maximum depth of 15.4 nm and an average thickness of the objects at the surface of 8.36 nm (as shown by the height distribution graph shown in FIG. 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 about 16 nm, in agreement with ellipsometric measurements.
• the particles are centrifuged, the supernatant removed and water is added to wash the particles. This procedure is repeated at least once more 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 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.
• EXAMPLE 5 Encapsulation of gold nanoparticles within a bilayer membrane formed from polystyrene-block-poly (acrylic acid) diblock copolymer
• the solid support is a planar silicon film functionalized as described in Example 1 .1 /.
• a monolayer of PS 40 3-b-PAA 6 3 is generated on the solid support as described in Example 1 .2 /.
• a solution of PS-3 40 b-PAA 63-1 g / L and hydrophobic gold nanoparticles (NP) (Diameter ⁇ 3-4 nm) to 1 ⁇ 10 6 NP / L in dimethylformamide / tetrahydrofuran (DMF / THF) (80/20) (v / v) is also prepared.
• This solution is added to the container containing the monolayer of PS 40 3-b-PAA 63 .
• Water is then added to this hybrid copolymer / nanoparticle solution, which has an initial volume of 3 ml, in order to trigger the self-assembly as described in Example 1 .3 /, to produce a symmetrical bilayer membrane.
• This addition is carried out at a flow rate of 0.3 ml / min using a syringe pump, so as to obtain, above the solid support, a solvent height of between 3 and 4 mm.
• the gold nanoparticles are encapsulated inside the bilayer membrane generated on the support, as well as in micelles formed in volume.
• the simultaneous steps of water injection and pumping of the solution make it possible to eliminate these hybrid micelles 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 under hood drying for 1 day.
• a symmetrical bilayer membrane formed from the amphiphilic block copolymer 20 and containing gold nanoparticles 23 encapsulated in the hydrophobic reservoir formed by the hydrophobic blocks of polystyrene 22.
• the bilayer thus self-assembled is characterized by measurement of contact angle and ellipsometry as described in Example 1. Its thickness measured by ellipsometry is 13 nm, a little more than twice the thickness of its first layer (5.8 nm).
• the solid support covered with this bilayer membrane loaded with gold nanoparticles is then characterized by conventional UV-visible transmission spectroscopy.
• the hydrophobic gold nanoparticles have a characteristic plasmon signature in the hydrophobic polystyrene reservoir at about 525 nm, suggesting successful encapsulation (continuous black curve).
• the dashed black curve represents the gold nanoparticles in solution (in the THF / DMF mixture) with their characteristic plasmon peak around 520 nm.
• the difference in absorbance between these two curves comes from a different probed volume in solution (50 mm cuvette) and in the bilayer membrane (about 35 nm).
• the slight displacement in wavelength comes from the change of dielectric environment of the nanoparticles while passing from the solution (THF / DMF) to the bilayer membrane.

Landscapes

• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Inorganic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Laminated Bodies (AREA)
• Separation Using Semi-Permeable Membranes (AREA)
• Application Of Or Painting With Fluid Materials (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=58669937

Family Applications (1)

Country Status (6)

Families Citing this family (11)

Family Cites Families (13)

• 2017
  • 2017-01-05 FR FR1750095A patent/FR3061440B1/fr not_active Expired - Fee Related
• 2018
  • 2018-01-03 EP EP18701512.8A patent/EP3565672A1/fr not_active Withdrawn
  • 2018-01-03 CN CN201880010263.7A patent/CN110300630B/zh not_active Expired - Fee Related
  • 2018-01-03 WO PCT/FR2018/050005 patent/WO2018127656A1/fr unknown
  • 2018-01-03 US US16/475,815 patent/US20200030750A1/en not_active Abandoned
  • 2018-01-03 JP JP2019536977A patent/JP6963619B2/ja active Active

Also Published As

Similar Documents

Legal Events