64 results about "Asymmetric membranes" patented technology

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.

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.

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.

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.

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 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.

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.

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.