Forming a dual layer filtration membrane includes disposing a first solution with a homopolymer and a first solvent on a substrate to yield a homopolymer layer on the substrate; disposing a second solution with a block polymer and a second solvent on the homopolymer layer to yield a dual layer liquid film having a block polymer layer on the homopolymer layer; disordering the block polymer layer to yield a disordered block polymer layer; vitrifying the disordered block polymer of the disordered block polymer layer and inducing phase separation and vitrification of the homopolymer of the homopolymer layer; and creating pores in the disordered block polymer layer to yield the dual layer filtration membrane having a porous disordered block polymer layer.

This invention allows for the production of high strength and high permeability TIPS membranes using extractable fillers with fine powder PVDF grades.

The present disclosure provides a flat-sheet polyamide membrane comprising a first major surface and a second major surface and a separation layer and a porous substructure in the cross section of the membrane between the first major and the second major surface, wherein the average pore size diameter in the separation layer is smaller than the average pore size diameters on the first and second major surfaces, wherein the average pore size diameter on the first major surface is larger than the average pore size diameter on the second major surface, wherein the separation layer is closer to the second major surface than to the first major surface. The present disclosure further provides a method for producing such membranes and a use of the membranes for nanofiltration or ultrafiltration purposes.

Embodiments of the present invention relate to a nanofiltration composite membrane for use to purify water, the methods for preparing said nanofiltration composite membranes and to the nanofiltration composite membranes prepared accordingly.

The porous hollow-fiber membrane of the present invention comprises a fluororesin polymer, and has columnar structures oriented in the longitudinal direction thereof. In the porous hollow-fiber membrane, molecular chains of the fluororesin polymer have been oriented in the longitudinal direction of the porous hollow-fiber membrane and have an average value ν of Raman orientation parameter of 1.5-4.0.

The present disclosure provides an acryloyloxy-terminated polydimethylsiloxane (AC-PDMS)-based thin-film composite (TFC) membrane, and a preparation method and use thereof. In the preparation method, a simple ultraviolet (UV)-induced monomer polymerization strategy based on high UV reactivity among acryloyloxy groups is adopted to prepare the AC-PDMS-based TFC membrane. The high UV reactivity among AC-PDMS monomers can induce the rapid curing of a casting solution to enable the formation of an ultra-thin selective layer and the inhibition of pore penetration for a substrate. By optimizing a UV wavelength, an irradiation time, and a polymer concentration, the prepared AC-PDMS-based TFC membrane has a CO.sub.2 penetration rate of 9,635 GPU and a CO.sub.2/N.sub.2 selectivity of 11.5. The UV-induced monomer polymerization strategy based on material properties provides a novel efficient strategy for preparing an ultra-thin PDMS-based membrane, which can be used for molecular separation.

The present invention relates to an ultrathin-film composite membrane based on a thermally rearranged poly(benzoxazole-imide) copolymer and a production method therefor and to a technique for forming a porous support by means of a thermally rearranged poly(benzoxazole-imide)copolymer and then producing, on the porous support, an ultrathin-film composite membrane comprising a thin-film active layer. The ultrathin-film composite membrane produced according to the present invention has excellent thermal/chemical stability and mechanical physical properties, thus is not only capable of withstanding high operating pressure, but also capable of minimizing internal concentration polarization and thereby obtaining high water permeance and, as a result, high power density, and thus can be applied to a pressure-retarded osmosis or forward osmosis process. Further, said ultrathin-film composite membrane has excellent chemical/thermal stability against organic solvents, has superior organic solvent nano-filtration performance, particularly maintains nano-filtration performance stably even under a high-temperature organic solvent condition, and thus can be applied as an organic solvent nano-filtration membrane.

The present invention relates to a composite porous hollow-fiber membrane including a first layer and a second layer which each include a fluororesin-based polymer, in which the first layer has a columnar texture oriented in a longitudinal direction of the composite porous hollow-fiber membrane, the columnar texture has an average value v of a Raman orientation parameter calculated with the specific formula, and the second layer has a three-dimensional network texture and has an average surface-pore diameter of 5.0 nm to 5.0 μm.

Polymer blends comprising an ortho-functionalized polyimide homo or copolymer and a polybenzimidazole homo or copolymer, wherein the ortho-functionalized polyimide thermally rearranges to a polymer comprising a phenylene heterocyclic group, such as, polybenzoxazole, polybenzothiazole, polybenzimidazole and/or other heterocyclic structure upon heating. Also disclosed are method of forming a polymer blend comprising dissolving an ortho-functionalized polyimide homo or copolymer and a polybenzimidazole homo or copolymer in a solvent, and optional compatibilizer, to form a polymer solution; contacting a support with the polymer solution; and evaporating the solvent to provide a thin layer comprising the polymer blend on the support. Further, methods of heat treating these polymer blends to thermally rearrange the disclosed polyimides are disclosed, as are the polymer blends prepared thereby. Methods of using these polymer blends to separate gases are also disclosed.

Hydrophobic hollow-fiber membrane made from a vinylidene fluoride polymer with a wall and a wall thickness, an outer surface on its outer side, an inner surface on its inner side and facing its lumen and adjacent to the inner surface a supporting layer having a structure that is substantially isotropic across the wall thickness, the supporting layer extending over at least 80% of the wall thickness and comprising pores having an average diameter of less than 1 m, and wherein the hollow-fiber membrane has pores on its outer surface and on its inner surface, characterized in that the vinylidene fluoride polymer has a weight-average molecular weight M.sub.W in the range from 550 000 to 700 000 daltons and a polydispersivity greater than 3.0; the pores in the outer and in the inner surface are formed like islands and have a maximum ratio of their longitudinal extension to the transverse extension of 10; the porosity lies in the range from 50 to 90 vol. %, the wall thickness in the range from 50 to 300 m, and the diameter of the lumen in the range from 100 to 500 m; and the hollow-fiber membrane has a maximum separating pore diameter d.sub.max in the range from 0.3 to 0.7 m, determined according to the bubble point method.