Porous membranes are provided according to the invention having desirable coefficient of thermal expansion and large surface area, for example at least about 4,000 mm.sup.2. These porous membranes may be made according to an exemplary process employing lithographic patterning of a photoresist followed by development of the photoresist and etching. In one aspect, the etch barrier layer is chosen from a material that does not react with or incorporate metal or other contaminants into the membrane layer.

Aerogel compositions, methods for preparing the aerogel compositions, articles of manufacture that include or are made from the aerogel compositions are described and uses thereof. The aerogels include a branched polyimide matrix with little to no crosslinked polymers.

Aerogel compositions, methods for preparing the aerogel compositions, articles of manufacture that include or are made from the aerogel compositions are described and uses thereof. The aerogels include a branched polyimide matrix with little to no crosslinked polymers.

A radioactive noble gas removal filter, a filter unit, and a nuclear reactor containment vessel vent system with improved durability are provided. The radioactive noble gas removal filter according to the present invention includes a polyimide film including a structural unit represented by general formula (1).

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A radioactive noble gas removal filter, a filter unit, and a nuclear reactor containment vessel vent system with improved durability are provided. The radioactive noble gas removal filter according to the present invention includes a polyimide film including a structural unit represented by general formula (1).

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Disclosed herein are vapour-phase crosslin ked composite membranes in the form of crosslinked polymers and defined inorganic materials. The membranes disclosed herein may have a narrow pore size distribution and precise molecule separation ability and may be used for organic solvent nanofiltration and organic solvent reverse osmosis. Also disclosed herein are methods of forming the membranes, and filtration. In a preferred embodiment, the vapour-phase crosslinked composite membrane is obtained by exposing a composite membrane comprising polyimide and UiO-66-NH.sub.2 particles to an amine vapour.

Disclosed herein are vapour-phase crosslin ked composite membranes in the form of crosslinked polymers and defined inorganic materials. The membranes disclosed herein may have a narrow pore size distribution and precise molecule separation ability and may be used for organic solvent nanofiltration and organic solvent reverse osmosis. Also disclosed herein are methods of forming the membranes, and filtration. In a preferred embodiment, the vapour-phase crosslinked composite membrane is obtained by exposing a composite membrane comprising polyimide and UiO-66-NH.sub.2 particles to an amine vapour.

A carbon molecular sieve (CMS) membrane having improved separation characteristics for separating olefins from their corresponding paraffins is comprised of carbon with at most trace amounts of sulfur and a group 13 metal. The CMS membrane may be made by pyrolyzing a precursor polymer devoid of sulfur in which the precursor polymer has had a group 13 metal incorporated into it, wherein the metal is in a reduced state. The pyrolyzing for the precursor having the group 13 metal incorporated into it is performed in a nonoxidizing atmosphere and at a heating rate and temperature such that the metal in a reduced state (e.g., covalently bonded to carbon or nitrogen or in the metal state).

The present invention relates to a chemically modified anion exchange membrane and a method of preparing the same and, more particularly, an anion exchange membrane in which sulfonic acid groups in a perfluorinated sulfonic acid electrolyte membrane are substituted with anion conductive groups such as ammonium group, phosphonium group, imidazolium group, pyridinium group and sulfonium group, and a method of preparing an anion exchange membrane by chemically modifying sulfonic acid groups in a perfluorinated sulfonic acid electrolyte membrane.

The present invention relates to a chemically modified anion exchange membrane and a method of preparing the same and, more particularly, an anion exchange membrane in which sulfonic acid groups in a perfluorinated sulfonic acid electrolyte membrane are substituted with anion conductive groups such as ammonium group, phosphonium group, imidazolium group, pyridinium group and sulfonium group, and a method of preparing an anion exchange membrane by chemically modifying sulfonic acid groups in a perfluorinated sulfonic acid electrolyte membrane.