185 results about "Porous polymer membrane" patented technology

A porous polymeric membrane formed from a blend of a polymeric membrane forming material, such as polyvinylidene fluoride or polysulfone and a polymeric reactivity modifying agent adapted to modify the surface active properties of the porous polymeric membrane. The reactivity modifying agent is preferably a linear polymeric anhydride, such as poly(alkyl vinyl ether/maleic anhydride). The surface activity modifications include modification of the hydrophilicity/hydrophobicity balance of the membrane, or hydrolysis followed by reaction with a polyamine to form a crosslinked polyamide layer. Such modified membranes have use as reverse osmosis membranes.

Porous polymeric membranes including Halar (poly (ethylene chlorotrifluoroethylene)) and related compounds and the methods of production thereof which avoid the use of toxic solvents. Preferred solvents, coating agents and pore forming agents are citric acid ethyl ester or glycerol triacetate. The membranes may be in the form of a hollow fibre or flat sheet, and may include other agents to modify the properties of the membrane, such as the hydrophilic/hydrophobic balance. Leachable agents may also be incorporated into the membranes.

A method of cleaning a porous polymeric membrane having a feed side and a permeate side including the steps of introducing a fluid containing a cleaning agent to the permeate side of a membrane allowing the cleaning agent to contact the permeate side of the membrane for a predetermined time, and contact the pores of the membrane, or introducing a fluid containing a cleaning agent to the feed side of a membrane; applying a transmembrane pressure to force the fluid containing the cleaning agent from the feed side to the permeate side of the membrane; allowing the cleaning agent to contact the permeate side of the membrane for a predetermined time, and contact the pores of the membrane. Preferably a concentration gradient between the feed side fluid and the lumen side fluid containing the cleaning agent causes cleaning agent to diffuse into the feed side fluid. Pressure may be applied to the fluid containing a cleaning agent to dislodge, where present, dissolved and undissolved solid from the membrane pores. The pressure may be applied in a pulsed fashion, and can be by way of compressed air at a pressure not more than the membrane's bubble point. The methods of the present invention may be preceded by, or followed with a backwash.

The present invention involves porous polymer membranes, suitable for use in medical implants, having controlled pore sizes, pore densities and mechanical properties. Methods of manufacturing such porous membranes are described in which a continuous fiber of polymer is extruded through a reciprocating extrusion head and deposited onto a substrate in a predetermined pattern. When cured, the polymeric material forms a stable, porous membrane suitable for a variety of applications, including reducing emboli release during and after stent delivery, and providing a source for release of bioactive substances to a vessel or organ and surrounding tissue.

The invention provides modified polysulfones substituted in one or more of the phenyl rings by functional groups and membranes composed of the modified polysulfones. Also provided are methods for the preparation of monodispersed nanoporous polymeric membranes. The membranes are useful for reverse osmosis, nanofiltration, and ultrafiltration, particularly for purification of water.

Provided is a method of producing a nanoparticle-filled phase inversion polymer electrolyte. The method includes mixing a nanoparticle inorganic filler and a polymer with a solvent to obtain a slurry; casting the obtained slurry to form a membrane; obtaining an inorganic nanoparticle-filled porous polymer membrane by developing internal pores in the cast membrane using a phase inversion method; and impregnating the inorganic nanoparticle-filled porous polymer membrane with an electrolytic solution. The polymer electrolyte produced using the method can be used in a small lithium secondary battery having a high capacity, thereby providing an excellent battery property.

A separator-electrolyte layer product for use in a lithium battery, comprising: (a) a porous thin-film separator selected from a porous polymer film, a porous mat, fabric, or paper made of polymer or glass fibers, or a combination thereof, wherein the separator has a thickness less than 500 μm; and (b) a non-flammable quasi-solid electrolyte containing a lithium salt dissolved in a liquid solvent up to a concentration no less than 3 M; wherein the porous thin-film separator is coated with the quasi-solid electrolyte so that the layer product exhibits a vapor pressure less than 0.01 kPa when measured at 20° C., a vapor pressure less than 60% of the vapor pressure of the liquid solvent alone, a flash point at least 20 degrees Celsius higher than a flash point of the first liquid solvent alone, a flash point higher than 150° C., or no detectable flash point.

A cross-linkable polyolefin composition (polyethylene, polypropylene or an ethylene-propylene copolymer) is coextruded with ultrahigh molecular weight polyethylene to form two-layer separator membranes, or three-layer separator membranes, for lithium-ion battery cells. In three-layer separator membranes, the cross-linkable polyolefin is formed as the outer faces of the separator for placement against facing surfaces of cell electrodes. The polymer materials initially contain plasticizer oil, which is removed from the extruded membranes, and the extruded membranes are also stretched to obtain a suitable open pore structure in the layered membranes to provide for suitable infiltration with a liquid electrolyte. The cross-linked polyolefin layer provides strength at elevated temperatures and the lower-melting, ultrahigh molecular weight polyethylene layer provides the separator membrane with a thermal shutdown capability.

Methods of forming a hydrophilic porous polymeric membrane which include preparing a porous polymeric membrane from a polymer blend which typically contains a hydrophobic non crosslinkable component (e.g. PVdF) and a component which is cross-linkable (for instance, PVP) and treating said porous polymeric membrane under cross linking conditions to produce a modified membrane with greatly improved water permeability and hydrophilic stability. Cross linking condition include chemical (e.g. peroxodisulfate species), thermal or radiation and/or combinations thereof. Non cross linked material may be washed out if desired.

By filling the pores of anodized porous alumina having a porous surface structure with a substance, and dissolving and removing the aforementioned anodized porous alumina, a stamper having an inverse structure of the aforementioned substance and having the aforementioned surface structure is manufactured. The aforementioned reverse structure of the aforementioned stamper is transferred to the polymer to manufacture a porous polymer film having the aforementioned surface structure. A large-area porous polymer membrane can be produced without complicated steps, and the porous polymer membrane has a surface structure in which pores of uniform size are perpendicular to the membrane surface.

A method is provided for substantially instantaneously wetting hydrophobic, porous polymeric membranes and for rendering hydrophobic membranes hydrophilic. The method involves treating the membrane with a non-alcoholic aqueous solution of a low molecular weight surfactant, and then drying the treated membrane. The low molecular weight surfactant exhibits high polymer affinity for the hydrophobic membrane substrate as well as high water solubility; a preferred surfactant is sodium dodecylbenzenesulfonate (SDBS). The method is particularly useful for treating hydrophobic membranes such as those made of polyolefins, fluorinated or chlorinated polymers, polysulfone, or polyethersulfone, preferably having a pore size of about 0.01 microns to about 1 micron. A wettable membrane is thus provided as the aqueous surfactant solution is absorbed into the hydrophobic membrane.

The invention discloses a method for preparing a modified composite nanofiltration membrane by constructing a pure COFs intermediate layer, which mainly includes: preparing TpPa-1 by using Schiff base condensation, constructing a pure COFs intermediate layer on a porous base membrane by vacuum filtration, and then A composite nanofiltration membrane is obtained through interfacial polymerization, wherein the porous base membrane is a polymer porous membrane with a pore diameter of 0.1 μm. In the present invention, by controlling the concentration of the aqueous phase monomer and the organic phase monomer in the interfacial polymerization step and the drying time after the interfacial polymerization reaction ends, the internal pore moisture and piperazine of the formed composite nanofiltration membrane can be effectively controlled. Molecules, that is, the hydrophilicity and porosity of the polyethersulfone-based membrane surface are optimized by vacuum filtration of the hydrophilic COFs intermediate layer, thereby realizing precise regulation of the interfacial polymerization process. The polyamide separation layer prepared by this method is thin and dense, Under the lower operating pressure (0.2MPa), it has higher water flux and maintains excellent separation performance.

The present disclosure provides a separator for an electrochemical device, comprising: a porous polymer film; and a porous coating layer formed on one or both surfaces of the porous polymer film and comprising at least one of inorganic particles and organic particles, and a binder polymer, wherein fibrils in the surface of the porous polymer film are entangled with the particles in the porous coating layer in the contact surface between the porous polymer film and the porous coating layer, and the separator has an air permeability of 100 to 800 sec/100 cc, an electrical resistance of 0.5 to 1.5Ω, and a heat-shrinkage rate of 8% or less in each of machine and transverse directions, and an electrochemical device having the same.