67 results about "Asymmetric membranes" patented technology

The invention provides asymmetric membranes composed of a microporous substrate whose pores contain a crosslinked gel, the density of the crosslinked gel being greater at or adjacent to one major surface of the membrane than the density at the other major surface. The membranes are useful for separating matter from liquids and display good flux and good rejection at low pressure.

The invention provides asymmetric membranes composed of a microporous substrate whose pores contain a crosslinked gel, the density of the crosslinked gel being greater at or adjacent to one major surface of the membrane than the density at the other major surface. The membranes are useful for separating matter from liquids and display good flux and good rejection at low pressure.

This invention relates to a method of making flat sheet asymmetric membranes, including cellulose diacetate / cellulose triacetate blended membranes, polyimide membranes, and polyimide / polyethersulfone blended membranes by formulating the polymer or the blended polymers dopes in a dual solvent mixture containing 1,3 dioxolane and a second solvent, such as N,N′-methylpyrrolidinone (NMP). The dopes are tailored to be closed to the point of phase separation with or without suitable non-solvent additives such as methanol, acetone, decane or a mixture of these non-solvents. The flat sheet asymmetric membranes are cast by the phase inversion processes using water as the coagulation bath and annealing bath. The dried membranes are coated with UV curable silicone rubber. The resulting asymmetric membranes exhibit excellent permeability and selectivity compared to the intrinsic dense film performances.

Improved integrally skinned asymmetric membranes for organic solvent nanofiltration, and their methods of preparation and use are disclosed. Membranes are formed from polyimides by phase inversion and are then crosslinked by addition of amine crosslinking agents that react with the imide groups of the polyimide, creating amide bonds. These stabilise the membranes and allow solvent nanofiltration to be maintained even in the solvents from which the membranes were formed by phase phase inversion.

Improved integrally skinned asymmetric membranes for organic solvent nanofiltration, and their methods of preparation and use are disclosed. Membranes are formed from polybenzimidazoles by phase inversion and are then crosslinked by addition of crosslinking agents. These stabilise the membranes and allow solvent nanofiltration to be maintained even in the solvents from which the membranes were formed by phase inversion, and in strongly acidic and strongly basic solvents.

The invention relates to a medicament carrier and a preparation method thereof, in particular to a medicament delivery system comprising biodegradable polymer vesicles with asymmetric membranes. The invention discloses the biodegradable polymer vesicles and preparation and application thereof. The biodegradable polymer vesicles are prepared from A-B-C type block polymer, wherein a block A is polyethylene glycol (PEG) distributed on outer surfaces of the vesicles; a block B is hydrophobic biodegradable polymer to form the nucleuses of the vesicles; and a block C is polyelectrolyte distributed on inner walls of the vesicular membranes and used for efficiently loading medicaments with opposite electric charge. The biodegradable polymer vesicles are formed in aqueous solution directly, can efficiently load protein and polypeptide medicaments, nucleic acid medicaments and micro-molecular medicaments, and are expected to be applied to the protein therapy and the combination therapy of cancers.

The present invention provides an osmotic dosage form comprising a core containing at least one pharmaceutically active ingredient and which also comprises at least one asymmetric membrane coating wherein said coating comprises one or more substantially water-insoluble polymers, and, one or more solid, water-soluble polymeric materials that do not generate significant amounts of hydrogen peroxide or formaldehyde in long term storage.

A stable method for producing liquid products such as ethanol, propanol, butanol and other chemicals from syngas components that contacts CO or a mixture of CO2 and H2 with a highly porous side of an asymmetric membrane under anaerobic conditions and transfers these components into contact with microorganisms contained within bio-pores of the membrane. A liquid contacting side of the membrane utilizes a dense layer to control hydration of the bio-pores with a liquid phase. The gas feed directly contacts the microorganisms in the bio-pores and maximizes their utilization of the syngas. Metabolic products produced by the microorganisms leave the membrane through the side opposite the entering syngas. This method establishes a unitary direction across the membrane for the supply of the primary feed source to the microorganisms and the withdrawal of metabolically produced products. The feed and product flow improves productivity and performance of the microorganism and the membrane.

Permselective asymmetric membranes suitable e.g. for hemodialysis, hemodiafiltration and hemofiltration of blood, and having improved sieving characteristics providing enhanced removal of middle molecular weight substances, e.g. inflammatory mediators having a molecular weight between 20 and 40 kDa. The membranes comprise polyethersulfone and polyvinylpyrrolidone and are coated with hyaluronic acid or copolymers of 2-methacryloyloxyethyl phosphoryl choline and other vinyl polymerizable monomers. Processes for the preparation of these membranes, devices comprising these membranes, and the use of these membranes in hemodialysis, hemodiafiltration and hemofiltration of blood, as well as in bioprocessing, plasma fractionation and the preparation of protein solutions.

This invention relates to a method of making flat sheet asymmetric membranes, including cellulose diacetate / cellulose triacetate blended membranes, polyimide membranes, and polyimide / polyethersulfone blended membranes by formulating the polymer or the blended polymers dopes in a dual solvent mixture containing 1,3 dioxolane and a second solvent, such as N,N′-methylpyrrolidinone (NMP). The dopes are tailored to be closed to the point of phase separation with or without suitable non-solvent additives such as methanol, acetone, decane or a mixture of these non-solvents. The flat sheet asymmetric membranes are cast by the phase inversion processes using water as the coagulation bath and annealing bath. The dried membranes are coated with UV curable silicone rubber. The resulting asymmetric membranes having a skin thickness of less than 100 nm, exhibit excellent permeability and selectivity compared to the intrinsic dense film performances.

One aspect of the present invention relates to a method for modifying one side of a PTFE membrane by using HFCVD to deposit a PTFE film on one side of the PTFE membrane. The precursor fluorocarbon gas is preferably hexafluoropropylene oxide, which upon pyrolysis under HFCVD conditions forms reactive CF2 species. The present invention also relates to a modified PTFE membrane having a PTFE film on only one side, wherein the PTFE film has a porosity of greater than about 30% and a dangling bond density of less than about 1018 spins / cm3. The invention further provides a method of filtering a liquid or gas or a mixture of the two, comprising passing the liquid or gas or mixture of the two through the modified PTFE membrane of the present invention.

The invention discloses a reversibly crosslinked biodegradable polymersome with an asymmetric membrane structure as well as a preparation method and application thereof to nucleic acid medicines. The polymersome and the preparation method have the advantages that a triblock polymer PEG-P(TMC-DTC)-PEI or PEG-P(DLLA-DTC)-PEI is synthesized and is self-assembled and self-crosslinked to obtain the polymersome with the asymmetric membrane structure or the triblock polymer is linked with a targeting molecule and is self-assembled to obtain targeting RCCPs; the inner shell of the polymersome is PEI and is used for compounding and loading nucleic acid through electrostatic interaction; a membrane is reversibly crosslinked biodegradable polyester / polycarbonate with good biocompatibility; dithiolane of a side chain is similar to a human body natural antioxidant lipoic acid; the outer shell of the polymersome takes PEG as the background and can target cancer cells; by studying that the carrier is compounded with functional siRNA and studying the gene silencing effects in vitro and vivo, in vivo blood circulation and bio-distribution, the condition of treating lung cancer in situ bearing mice and toxic and side effects of the polymersome, the polymersome is expected to become a nanosystem platform integrating the advantages of simplicity, stability, multifunction, and the like and is used for carrying out efficient and active targeting delivery on siRNA to tumors in situ.

The present invention is directed to composite filters and methods for preparing same. More specifically, it is directed to filter laminates of multiple discreet layers of material bonded together, with at least one of the layers being an asymmetric membrane.

The invention discloses dual layer-coated membranes and methods for making and using these membranes. The dual layer-coated membranes have a relatively porous and substantial void-containing selective asymmetric membrane support, a first coating layer comprising a hydrogel, and a second coating layer comprising a hydrophobic fluoropolymer. The membrane support has low selectivity and high permeance. The dual layer coating improves the selectivity of the membrane support and maintains the membrane performance with time. The dual layer-coated membranes are suitable for a variety of liquid, gas, and vapor separations such as water purification, non-aqueous liquid separation such as deep desulfurization of gasoline and diesel fuels, ethanol / water separations, pervaporation dehydration of aqueous / organic mixtures, fuel gas conditioning, CO2 / CH4, He / CH4, CO2 / N2, H2 / CH4, O2 / N2, olefin / paraffin, iso / normal paraffins separations, and other light gas mixture separations. The dual layer-coated membranes are especially useful for natural gas liquid (NGL) recovery and CO2 removal from natural gas.

A multipolymeric mixture is provided that includes a hydrophobic polymer, two different grades of a water-soluble polymer, water as non-solvent and a solvent suitable for all polymers involved. The dissolved hydrophobic polymer has the affinity to enmesh the water-soluble polymers to form a clear and viscous dope. Water-soluble polymers contribute to the pore formation process and hydrophilicity of the finally coagulated membrane according to the makeup of their molecular weight distribution.Water as a non-solvent takes the dope very near towards unstable zone, which helps in speeding up the membrane formation process in a diffusion induced phase inversion technique. The dope is then spun through a concentric orifice spinneret and solidified by passing it through a coagulation bath to form hollow fiber asymmetric membranes of ultra filtration grade with superior water permeability and separation characters even at higher feed turbidity.

Immersion precipitation of solutions having 15%-30% (w / w) and various molecular weights of the emeraldine base form of polyaniline in polar aprotic solvents are shown to form integrally skinned asymmetric membranes and fibers having skin layers <1 μm thick which exhibit improved rates of gas transport while preserving good selectivity. These membranes can be further transformed by an acid doping process after fabrication to achieve excellent permeation rates and high selectivities for particular gas separations. Prior to the use of concentrated EB solutions, the formation of integrally skinned asymmetric membranes was not possible, since films and fibers made from <5% w / w polyaniline solutions were found to disintegrate during the IP process.

The present invention provides a method for the preparation of an asymmetric membranes. More particularly, the new method relates to the use of a crosslinker contacted via vapour or liquid phase with the surface layer of a cast polymer film, followed by the immersion of said film in a coagulation bath. The formation of a crosslinked skin layer and the solidification of the membrane bulk can thus be decoupled in time.

A multipolymeric mixture is provided that includes a hydrophobic polymer, two different grades of a water-soluble polymer, water as non-solvent and a solvent suitable for all polymers involved. The dissolved hydrophobic polymer has the affinity to enmesh the water-soluble polymers to form a clear and viscous dope. Water-soluble polymers contribute to the pore formation process and hydrophilicity of the finally coagulated membrane according to the makeup of their molecular weight distribution.Water as a non-solvent takes the dope very near towards unstable zone, which helps in speeding up the membrane formation process in a diffusion induced phase inversion technique. The dope is then spun through a concentric orifice spinneret and solidified by passing it through a coagulation bath to form hollow fiber asymmetric membranes of ultra filtration grade with superior water permeability and separation characters even at higher feed turbidity.

The invention discloses a fluorine-containing polymer film, and a preparation method and an application thereof. The fluorine-containing polymer film is prepared from raw material components includinga fluorine-containing polymer, a modification additive, a fluorine-containing polymer good solvent and a fluorine-containing polymer poor solvent through a steam-induced phase separation method, thefluorine-containing polymer film has the properties of a symmetric film or an asymmetric film, the microstructure of the fluorine-containing polymer film comprises compact, nodular and cellular pores,the porosity of the fluorine-containing polymer film is 20-85%, and the pore size range of the fluorine-containing polymer film is 150-3000 nm. The fluorine-containing polymer film can be a symmetricor asymmetric film, is adjustable in microstructure, surface performance, porosity and pore size, has an application prospect in the separation fields such as microfiltration, ultrafiltration, oil-water separation and emulsion oil-water separation, and can also be used for a battery diaphragm.

The invention discloses an anti-tumor nano-adjuvant based on cross-linked biodegradable polymer vesicles and a preparation method and application thereof. The nano-adjuvant is obtained by loading drugs with reversibly cross-linked biodegradable polymer vesicles with asymmetric membrane structure. The drug is an oligonucleotide capable of activating the immune response. Degradable polymer vesiclesare obtained by cross-linking after self-assembly of polymers. The molecular chain of the polymer includes successively connected hydrophilic segments, hydrophobic segments and positively charged molecules. The hydrophobic segments are polycarbonate segments and / or polyester segments that are compounded and loaded with drugs through electrostatic interaction. The film is a polycarbonate and / or polyester segment that is reversibly cross-linked, biodegradable and biocompatible. The side chain of dithiolane is similar to natural antioxidant lipoic acid of the human body. The outer shell is basedon PEG, and can target cancer cells. The adjuvant is expected to become a nano-vaccine or nano-immune adjuvant that integrates the advantages of simplicity, stability, and multi-function, and can be used for efficient tumor immunotherapy.

Improved integrally skinned asymmetric membranes for organic solvent nanofiltration, and their methods of preparation and use are disclosed. Membranes are formed from polyimides by phase inversion and are then crosslinked by addition of amine crosslinking agents that react with the imide groups of the polyimide, creating amide bonds. These stabilize the membranes and allow solvent nanofiltration to be maintained even in the solvents from which the membranes were formed by phase inversion.

The invention discloses a drug-loaded polymer vesicle with an asymmetric membrane structure, a preparation method and application in preparation of a drug for treating acute myeloid leukemia. An amphiphilic triblock polymer with polyaspartic acid PAsp, a targeted amphiphilic block polymer and a small molecule drug are assembled together to prepare the targeted small molecule drug-loaded polymer vesicle with the asymmetric membrane structure. The drug-loaded polymer vesicle disclosed by the invention has many unique advantages, including small size, simple and controllable preparation, reversible crosslinking, in-vivo stability, targeted delivery, high intracellular drug enrichment concentration, sensitive reduction, efficient killing of tumor cells, significant tumor growth inhibition effect and the like, and especially the drug-loaded vesicle disclosed by the invention has effective inhibition on both acute myeloid leukemia cell lines and patient cells. Therefore, the polymer vesicleis expected to become a simple and multifunctional nano platform for efficient and specific targeted delivery of drugs to tumor cells.

Provided herein are methods of making asymmetric membranes comprising a first layer and a second layer. The methods include preparing a polymeric solution comprising one or more polymers, casting the polymeric solution to form a polymeric film, contacting the polymeric film with a solvent comprising a crosslinker under conditions to form a first layer on the top of the film, wherein the first layer is dense and solvent resistant, and contacting the polymeric film having the dense, solvent-resistant first layer with a non-solvent solution under conditions that form a porous second layer on the bottom of the film.

The present invention relates to membranes being suitable e.g. for hemodialysis, hemodiafiltration, or hemofiltration of blood. The invention also relates to a process for the production of the membranes; and to devices comprising the membranes.

Asymmetric membranes comprising a first asymmetric porous zone including a first porous asymmetry that increases from the first exterior surface through the first porous zone of the bulk, and a second asymmetric porous zone including a second porous asymmetry that increases from the second exterior surface through the second porous zone of the bulk, wherein the first average pore size is larger than the second average pore size, as well as methods of making and using the membranes, are disclosed.

Asymmetric membranes in hollow fiber and flat sheet forms are disclosed herewith. The process of preparation of the membranes is further disclosed. The membranes are characterized and find application in the separation of gases and solutes.

The present invention refers to polymeric membranes and its synthesis with combination of innovative characteristics at the level of the bi-soft segment polyurethane material and at the level of the structure as integral asymmetric membranes. The hemocompability properties—non-hemolytic, non-thrombogenic and no platelet adhesion—combined with the high fluxes of permeation of O2 and CO2 have been designed for the use of the membranes in medical equipments that involve contact with blood like extracorporeal blood oxygenators and can be further designed for hemodialysers and imunnisolation barriers.

An asymmetric membrane having a layer containing a zeolite supported on a geopolymer substrate and methods for making an asymmetric membrane having a layer containing a zeolite supported on a geopolymer substrate. A cross-flow membrane separation method for increasing the concentration of ethanol from a feed mixture comprising water and ethanol, comprising: cross-flowing a feed mixture comprising water and ethanol across the layer comprising a zeolite of the asymmetric membrane of the instant invention to produce a permeate having an ethanol concentration less than the ethanol concentration of the feed mixture and a retentate having an ethanol concentration greater than the ethanol concentration of the feed mixture, the pressure of the feed mixture being greater than the pressure of the permeate.