A preparation method of separation membrane is provided. First, a polyimide composition including a dissolvable polyimide, a crosslinking agent and a solvent is provided. The dissolvable polyimide is represented by formula 1:

##STR00001## wherein B is a tetravalent organic group derived from a tetracarboxylic dianhydride containing aromatic group, A is a divalent organic group derived from a diamine containing aromatic group, A′ is a divalent organic group derived from a diamine containing aromatic group and carboxylic acid group, and 0.1≦X≦0.9. The crosslinking agent is an aziridine crosslinking agent, an isocyanate crosslinking agent, an epoxy crosslinking agent, a diamine crosslinking agent, or a triamine crosslinking agent. A crosslinking process is performed on the polyimide composition. The polyimide composition which has been subjected to the crosslinking process is coated on a substrate to form a polyimide membrane. A wet phase inversion process is performed on the polyimide membrane.

A preparation method of separation membrane is provided. First, a polyimide composition including a dissolvable polyimide, a crosslinking agent and a solvent is provided. The dissolvable polyimide is represented by formula 1:

##STR00001## wherein B is a tetravalent organic group derived from a tetracarboxylic dianhydride containing aromatic group, A is a divalent organic group derived from a diamine containing aromatic group, A′ is a divalent organic group derived from a diamine containing aromatic group and carboxylic acid group, and 0.1≦X≦0.9. The crosslinking agent is an aziridine crosslinking agent, an isocyanate crosslinking agent, an epoxy crosslinking agent, a diamine crosslinking agent, or a triamine crosslinking agent. A crosslinking process is performed on the polyimide composition. The polyimide composition which has been subjected to the crosslinking process is coated on a substrate to form a polyimide membrane. A wet phase inversion process is performed on the polyimide membrane.

System, devices, and method for the production of thin film composite hollow fiber membranes on a hollow fiber support structure. The system includes a comb and roller device, or comb and dual roller device, which can be used to define a submerged travel path in a first solution bath for a hollow fiber. The combs and rollers control the amount of time the hollow fiber spends in the first solution. The first solution contains a first monomer, and the hollow fiber is impregnated with the first monomer. The amount of impregnation depends on the time spent in the first solution. Subsequent immersion in a second solution containing a second monomer results in the formation of a thin film composite hollow fiber membrane.

System, devices, and method for the production of thin film composite hollow fiber membranes on a hollow fiber support structure. The system includes a comb and roller device, or comb and dual roller device, which can be used to define a submerged travel path in a first solution bath for a hollow fiber. The combs and rollers control the amount of time the hollow fiber spends in the first solution. The first solution contains a first monomer, and the hollow fiber is impregnated with the first monomer. The amount of impregnation depends on the time spent in the first solution. Subsequent immersion in a second solution containing a second monomer results in the formation of a thin film composite hollow fiber membrane.

Reverse osmosis membranes made by interfacial polymerization of a monomer in a nonpolar (e.g. organic) phase together with a monomer in a polar (e.g. aqueous) phase on a porous support membrane. Interfacial polymerization process is disclosed for preparing a highly permeable RO membrane, comprising: contacting on a porous support membrane, a) a first solution containing 1,3-diaminobenzene, and b) a second solution containing trimesoyl chloride, wherein at least one of solutions a) and b) contains nanoparticles when said solutions are first contacted, and recovering a highly permeable RO membrane.

Reverse osmosis membranes made by interfacial polymerization of a monomer in a nonpolar (e.g. organic) phase together with a monomer in a polar (e.g. aqueous) phase on a porous support membrane. Interfacial polymerization process is disclosed for preparing a highly permeable RO membrane, comprising: contacting on a porous support membrane, a) a first solution containing 1,3-diaminobenzene, and b) a second solution containing trimesoyl chloride, wherein at least one of solutions a) and b) contains nanoparticles when said solutions are first contacted, and recovering a highly permeable RO membrane.

Described herein are crosslinked polymeric based composite membranes that provide selective resistance for gases while providing water vapor permeability. Such composite membranes have a high water/air selectivity in permeability. The methods for making such membranes and using the membranes for dehydrating or removing water vapor from gases are also described.

A membrane for the purification of blood, or a dialysis membrane, in hollow-fiber membrane or flat membrane geometry, made of a composite assembled from at least a base membrane based on at least one polysulfone or a polyphenylsulfone with at least one pore-forming hydrophilic additive and at least one functional layer arranged on the base membrane, whereby the functional layer is formed from at least one polymeric polycationic bonding agent and at least one polymeric polyanion, whereby the base membrane is made of a material which is selected from: a polysulfone [PSU], a sulfonated polysulfone [SPSU], a polyethersulfone [PES], a sulfonated polyethersulfone [SPES], a polyphenylsulfone [PPSU], a sulfonated polyphenylsulfone [SPPSU]; and mixtures of these.

A membrane for the purification of blood, or a dialysis membrane, in hollow-fiber membrane or flat membrane geometry, made of a composite assembled from at least a base membrane based on at least one polysulfone or a polyphenylsulfone with at least one pore-forming hydrophilic additive and at least one functional layer arranged on the base membrane, whereby the functional layer is formed from at least one polymeric polycationic bonding agent and at least one polymeric polyanion, whereby the base membrane is made of a material which is selected from: a polysulfone [PSU], a sulfonated polysulfone [SPSU], a polyethersulfone [PES], a sulfonated polyethersulfone [SPES], a polyphenylsulfone [PPSU], a sulfonated polyphenylsulfone [SPPSU]; and mixtures of these.

Membranes, methods of making the membranes, and methods of using the membranes are described herein. The membrane can comprise a support layer; and a selective polymer layer disposed (e.g., coated) on the support layer. The selective polymer layer can comprise a polymer matrix (e.g., a hydrophilic polymer, an amine-containing polymer, or a combination thereof), and a guanidine-based mobile carrier dispersed within the polymer matrix. Optionally, the selective polymer later can further include an amine-based mobile carrier, a CO.sub.2-philic ether, a graphene oxide, carbon nanotubes, or a combination thereof, dispersed within the polymer matrix. The membranes can be used to separate carbon dioxide from other gases, such as hydrogen and/or nitrogen. Also provided are methods of separating gas streams using the membranes described herein.