Process for harvesting helium gas by harnessing greenhouse gas-free geologic hydrogen

Abstract

The present disclosure relates to a process for isolation of He, comprising a) contacting a first gas separation membrane with a first gas stream comprising He and H2, thereby producing a second gas stream comprising He and H2; b) contacting the second gas stream with air under conditions sufficient to combust the H2, thereby producing a third gas stream comprising He; c) contacting a second gas separation membrane with the third gas stream, thereby producing a fourth gas stream comprising He.

Description

[0001] PROCESS FOR HARVESTING HELIUM GAS BY HARNESSING GREENHOUSE GAS- FREE GEOLOGIC HYDROGEN

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U. S. Provisional Patent Application No. 63 / 710242, filed October 22, 2024, the contents of which are incorporated herein by reference in their entirety.

[0003] BACKGROUND OF THE INVENTION

[0004] It has been estimated that 23 Mt of geologic H2 could be produced globally per year, which would represent 24% of total H2 demand. Many geologic formations demonstrate cooccurrence of helium and geologic H2. There are significant sources of co-mingled H2 and helium gas in central North America. Access to helium presents an urgent concern for the U. S. economy. Today, 30% of the US domestic helium supply is used for the healthcare industry, primarily for MRIs. Another 14% of supply is needed for laboratory research and analytical characterization methods, and an equivalent amount is used in manufacturing (primarily for welding and semiconductors). The passage of the Helium Stewardship Act in 2013 required a slow depletion of the National Helium Reserve and a privatization of the helium industry. This regulatory change has resulted in substantial price fluctuations. According to the U. S. Geological Survey, grade- A helium nearly doubled in price between 2021 and 2023, forcing experiments to halt at advanced research labs reliant on the gas. These issues are exacerbated by geopolitical conflict. Russia is poised to become the world’s third largest helium supplier, and its exports are largely allocated for China, in part to support China’s growing semiconductor manufacturing demands. In addition to national security and supply chain concerns, almost all helium production entails substantial green house gas (GHG) emissions. Therefore, more efficient and environmentally friendly sources of helium are needed. SUMMARY OF THE INVENTION

[0005] In some embodiments the present disclosure relates to a process for isolation of He, comprising a) contacting a first gas separation membrane with a first gas stream comprising He and H₂, thereby producing a second gas stream comprising He and H₂;

[0006] b) contacting the second gas stream with air under conditions sufficient to combust the H₂, thereby producing a third gas stream comprising He; and

[0007] c) contacting a second gas separation membrane with the third gas stream, thereby producing a fourth gas stream comprising He.

[0008] BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The foregoing will be apparent from the following more particular description of example embodiments of the invention, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating embodiments of the present invention.

[0010] FIG. 1 is a schematic representation of the process of isolation of He from a geologic gas stream.

[0011] FIG. 2 shows a diagram of the apparatus used for spinning the substrate.

[0012] FIG. 3 shows a diagram of the apparatus used for coating the substrate.

[0013] DETAILED DESCRIPTION OF THE INVENTION

[0014] A description of example embodiments of the invention follows.

[0015] The U. S. has identified new helium sources that are in the national interest to extract, but since they are not part of large natural gas deposits, they cannot be economically extracted using existing practices. In some embodiments, the processes of the present disclosure not only enable the extraction of currently inaccessible helium sources but also produce high-purity helium using geologic H2 as a GHG-free primary energy source. Current helium production requires cryogenic distillation powered by the combustion of the natural gas with which it co-occurs, producing substantial GHG emissions. The process described herein displaces the need for natural gas by combusting geologic H2 to deliver energy for helium purification. This also addresses a primary issue associated with geologic H2. Even though geologic H2 is an abundant primary energy source, geographic remoteness poses a major issue for transmission. In some embodiments, on-site use for helium purification bypasses this issue by negating the need for H2 transportation infrastructure. While other gas separation technologies could be applied, they are limited in practice. The low selectivity of commercially available helium separation membranes necessitates a high recycle rate, requiring substantial compression utility. High energy requirements are mirrored in cryogenic distillation processes and are unsuitable for on-site wellhead He purification as these they lack efficiency at low and intermediate scales. While pressure swing adsorption is well-suited to polishing high concentrations of helium to 99%+ purity, it cannot effectively process low concentrations (<50- 80%). In some embodiments, the processes described herein use geologic H2 to enhance the viability and lower the emissions of new helium sources, which both enhances U. S. energy security with a new domestic zero-emissions primary energy source and enhances economic security by opening new supplies of helium, a critical resource characterized by periodic global shortages.

[0016] Most helium is separated from natural gas using energy-intensive cryogenic distillation at natural gas liquefaction facilities, which is generally powered by burning natural gas. This concept paper aims to address all of these challenges by introducing a new reactive separation process that harnesses He / H2 well compositions in the U. S. that can enable this technology.

[0017] Dilute helium feeds from wells recently discovered in Montana demonstrate favorable well-head pressures (1,500-2,000 psi), helium concentrations of approximately 0.8-3.9%, and 5-27% H2 content. These feeds present an opportunity to pilot a GHG-free means of helium harvesting utilizing geologic H2 as an abundant primary energy source. Compositional uncertainty associated with the novelty of these wells necessitates subsurface mapping, such as gas-phase subsurface mapping and field tests for accurate compositional analysis.

[0018] In some embodiments, the present disclosure relates to a separating the geologic gas streams using a membrane having H2 / He-based selectivities to other relevant gases such as N2. In some embodiments, the membrane selectivities are 100% higher than any other commercial membrane material. This high selectivity coupled with high flux provides a He / H2-enriched stream to an air- fed H2-burning electric generator (such as GE’s flexible gas turbines) to be mixed with air. The combustion consumes the H2 and leaves behind He mixed with GHG-free exhaust, generating the power needed to pressurize the permeate for the final membrane separation to remove combustion gas and produce crude helium for sale. A summary of the overall process can be found in FIG. 1.

[0019] In the table below, all estimated metrics are for a feed of 5% He, 5% H2, and 90% N2 at a pressure of 1,000 psia and a temperature of 35 °C for a 99% first-pass helium recovery rate.

[0020]

[0021] In some embodiments, H2fuel cells can be used to generate electricity for the gas compressors, but the sensitivity of fuel cells to non-H2gases requires extensive gas separation, driving up energy requirements beyond what is likely possible with geologic H2concentrations. H2-burning generators are far more robust and can be readily obtained from mature commercial suppliers. General Electric produces proven H2-burning electric generators, and the technology used to drill for the He-H2deposits is the same used in the oil and gas sector. The unknowns around well composition and pressure will be the core drivers for this project’s potential risks and technical challenges. First, H2concentration could be too low to provide sufficient electrical power output from the H2-burning generator to drive the gas compressors, reducing membrane productivity. Second, substantial CH4could be found in the He / H2gas mixture (rather than N2), resulting in CO2generation during electricity generation and different gas separation performance in the final helium purification step. These technical risks will be assessed and evaluated by performing extensive gas reserve qualification. In some embodiments, field tests at multiple well sites can be conducted. If H2concentration is too low to power pumps for the disclosed process, geologic H2stimulation can be performed. Finally, if substantial CH4is present, partial oxidation of methane (POM) can be integrated into the process. POM produces H2gas, which can be used for power. Norbornyl benzocyclobutene polymers have highly rigid and contorted backbone, preventing the efficient packing of polymer chains in the solid state and leading to the formation of angstrom-sized pores in the polymer matrix. By forming the norbornyl benzocyclobutene polymers into membranes, the resulting pores can be leveraged for size-selective molecular separations (WO2021101659A3). The exceptional gas separation performance of norbornyl benzocyclobutene polymer membranes have been demonstrated in permeation experiments of thick (>5 um) films (Lai et al. Science 2022, 375 (6587), 1390-1392). After aging of the polymer films, H2 / CH4 selectivity of >600 was demonstrated in pure-gas permeation experiments, surpassing the performance of virtually all solution processable polymeric membranes.

[0022] Additionally, high-pressure CO2 / CH4 mixed-gas permeation experiments demonstrated selectivity >50. Norbornyl benzocyclobutene polymer membranes also has exceptional separation performance for other industrially relevant gas pairs such as O2 / N2, H2 / N2, and H2 / CO2.

[0023] While thick polymer films can be excellent for understanding fundamental polymer properties, they are impractical for industrial applications due to their low flux. Transport resistance of membranes is generally proportional to the thickness of the selective layer. The low permeance of thick films means that much larger membrane areas would be required to achieve a certain throughput, greatly increasing membrane capital expenses. For industrial applications, norbornyl benzocyclobutene membranes with thicknesses of <1 um are necessary. Additionally, previous work demonstrated that long-term aging (> 150 days) is required for thick films of norbornyl benzocyclobutene polymer membranes to achieve the high selectivity reported. To address both of the above challenges, provided herein is a general method for the fabrication of thin-film composite (TFC) membranes with norbornyl benzocyclobutene polymers as the selective layer. Even without long-term aging of the selective layer, the thin-film composite membranes have gas selectivity exceeding those previously reported for aged thick films.

[0024] Hollow fiber polymer membranes have several important advantages over “flat-sheet” membranes for gas separations, including, for example, low production cost, high area packing density, high effective surface area, increased mechanical flexibility, mechanical self-support, and relative ease of production at scale. In certain embodiments, the hollow fiber has an outer diameter of about 200- 800 microns. In further embodiments, the hollow fiber has an inner diameter of about 50- 400 microns. In further embodiments, the hollow fiber has a fiber length of about 100 meters or less.

[0025] Definitions

[0026] Unless otherwise defined herein, scientific and technical terms used in this application shall have the meanings that are commonly understood by those of ordinary skill in the art. Generally, nomenclature used in connection with, and techniques of, chemistry described herein, are those well-known and commonly used in the art.

[0027] The methods and techniques of the present disclosure are generally performed, unless otherwise indicated, according to conventional methods well known in the art and as described in various general and more specific references that are cited and discussed throughout this specification.

[0028] Chemistry terms used herein, unless otherwise defined herein, are used according to conventional usage in the art, as exemplified by “The McGraw-Hill Dictionary of Chemical Terms”, Parker S., Ed., McGraw-Hill, San Francisco, C. A. (1985).

[0029] All of the above, and any other publications, patents and published patent applications referred to in this application are specifically incorporated by reference herein. In case of conflict, the present specification, including its specific definitions, will control.

[0030] As used herein, the terms “optional” or “optionally” mean that the subsequently described event or circumstance may occur or may not occur, and that the description includes instances where the event or circumstance occurs as well as instances in which it does not. For example, “optionally substituted alkyl” refers to the alkyl may be substituted as well as where the alkyl is not substituted.

[0031] It is understood that substituents and substitution patterns on the compounds described herein can be selected by one of ordinary skilled person in the art to result chemically stable compounds which can be readily synthesized by techniques known in the art, as well as those methods set forth below, from readily available starting materials. If a substituent is itself substituted with more than one group, it is understood that these multiple groups may be on the same carbon or on different carbons, so long as a stable structure results.

[0032] As used herein, the term “optionally substituted” refers to the replacement of one to six hydrogen radicals in a given structure with the radical of a specified substituent including, but not limited to: hydroxy, hydroxyalkyl, alkoxy, halogen, alkyl, nitro, silyl, acyl, acyloxy, aryl, cycloalkyl, heterocyclyl, amino, aminoalkyl, cyano, haloalkyl, haloalkoxy, -OCO-CH2-O-alkyl, -OP(O)(O-alkyl)2 or -CH2-OP(O)(O-alkyl)2. Preferably, “optionally substituted” refers to the replacement of one to four hydrogen radicals in a given structure with the substituents mentioned above. More preferably, one to three hydrogen radicals are replaced by the substituents as mentioned above. It is understood that the substituent can be further substituted.

[0033] As used herein, the term “alkyl” refers to saturated aliphatic groups, including but not limited to C1-C10 straight-chain alkyl groups or C1-C10 branched-chain alkyl groups. Preferably, the “alkyl” group refers to C1-C6straight-chain alkyl groups or C1-C6branched-chain alkyl groups. Most preferably, the “alkyl” group refers to C1-C4 straight-chain alkyl groups or C1-C4 branched-chain alkyl groups. Examples of “alkyl” include, but are not limited to, methyl, ethyl, 1 -propyl, 2-propyl, n-butyl, sec -butyl, tert-butyl, 1 -pentyl, 2-pentyl, 3-pentyl, neo-pentyl, 1-hexyl, 2-hexyl, 3-hexyl, 1 -heptyl, 2-heptyl, 3-heptyl, 4-heptyl, 1 -octyl, 2-octyl, 3-octyl or 4-octyl and the like. The “alkyl” group may be optionally substituted.

[0034] The term “acyl” is art-recognized and refers to a group represented by the general formula hydrocarbylC(O)-, preferably alkylC(O)-.

[0035] The term “acylamino” is art-recognized and refers to an amino group substituted with an acyl group and may be represented, for example, by the formula hydrocarbylC(O)NH-.

[0036] The term “acyloxy” is art-recognized and refers to a group represented by the general formula hydrocarbylC(O)O-, preferably alkylC(O)O-.

[0037] The term “alkoxy” refers to an alkyl group having an oxygen attached thereto.

[0038] Representative alkoxy groups include methoxy, ethoxy, propoxy, tert-butoxy and the like.

[0039] The term “alkoxyalkyl” refers to an alkyl group substituted with an alkoxy group and may be represented by the general formula alkyl-O-alkyl.

[0040] The term “alkyl” refers to saturated aliphatic groups, including straight-chain alkyl groups, branched-chain alkyl groups, cycloalkyl (alicyclic) groups, alkyl-substituted cycloalkyl groups, and cycloalkyl-substituted alkyl groups. In preferred embodiments, a straight chain or branched chain alkyl has 30 or fewer carbon atoms in its backbone (e.g., C1-30 for straight chains, C3-30 for branched chains), and more preferably 20 or fewer.

[0041] Moreover, the term “alkyl” as used throughout the specification, examples, and claims is intended to include both unsubstituted and substituted alkyl groups, the latter of which refers to alkyl moieties having substituents replacing a hydrogen on one or more carbons of the hydrocarbon backbone, including haloalkyl groups such as trifluoromethyl and 2,2,2-trifluoroethyl, etc.

[0042] The term “Cx-y” or “Cx-Cy”, when used in conjunction with a chemical moiety, such as, acyl, acyloxy, alkyl, alkenyl, alkynyl, or alkoxy is meant to include groups that contain from x to y carbons in the chain. Coalkyl indicates a hydrogen where the group is in a terminal position, a bond if internal. A Ci-ealkyl group, for example, contains from one to six carbon atoms in the chain.

[0043] The term “alkylamino”, as used herein, refers to an amino group substituted with at least one alkyl group.

[0044] The term “alkylthio”, as used herein, refers to a thiol group substituted with an alkyl group and may be represented by the general formula alkylS-.

[0045] The term “amide”, as used herein, refers to a group

[0046] O

[0047] T

[0048] R10

[0049] wherein R9and R10each independently represent a hydrogen or hydrocarbyl group, or R9and R10taken together with the N atom to which they are attached complete a heterocycle having from 4 to 8 atoms in the ring structure.

[0050] The terms “amine” and “amino” are art-recognized and refer to both unsubstituted and substituted amines and salts thereof, e.g., a moiety that can be represented by

[0051]

[0052] wherein R9, R10, and R10’ each independently represent a hydrogen or a hydrocarbyl group, or R9and R10taken together with the N atom to which they are attached complete a heterocycle having from 4 to 8 atoms in the ring structure.

[0053] The term “aminoalkyl”, as used herein, refers to an alkyl group substituted with an amino group.

[0054] The term “aralkyl”, as used herein, refers to an alkyl group substituted with an aryl group. The term “aryl” as used herein includes substituted or unsubstituted single-ring aromatic groups in which each atom of the ring is carbon. Preferably the ring is a 5- to 7-membered ring, more preferably a 6-membered ring. The term “aryl” also includes polycyclic ring systems having two or more cyclic rings in which two or more carbons are common to two adjoining rings wherein at least one of the rings is aromatic, e.g., the other cyclic rings can be cycloalkyls, cycloalkenyls, cycloalkynyls, aryls, heteroaryls, and / or heterocyclyls. Aryl groups include benzene, naphthalene, phenanthrene, phenol, aniline, and the like.

[0055] The term “carbamate” is art-recognized and refers to a group

[0056] Rio

[0057]

[0058] wherein R9and R10independently represent hydrogen or a hydrocarbyl group.

[0059] The term “carbocyclylalkyl”, as used herein, refers to an alkyl group substituted with a carbocycle group.

[0060] The term “carbocycle” includes 5-7 membered monocyclic and 8-12 membered bicyclic rings. Each ring of a bicyclic carbocycle may be selected from saturated, unsaturated and aromatic rings. Carbocycle includes bicyclic molecules in which one, two or three or more atoms are shared between the two rings. The term “fused carbocycle” refers to a bicyclic carbocycle in which each of the rings shares two adjacent atoms with the other ring. Each ring of a fused carbocycle may be selected from saturated, unsaturated and aromatic rings. In an exemplary embodiment, an aromatic ring, e.g., phenyl, may be fused to a saturated or unsaturated ring, e.g., cyclohexane, cyclopentane, or cyclohexene. Any combination of saturated, unsaturated and aromatic bicyclic rings, as valence permits, is included in the definition of carbocyclic.

[0061] Exemplary “carbocycles” include cyclopentane, cyclohexane, bicyclo [2.2. l]heptane, 1,5- cyclooctadiene, 1,2,3,4-tetrahydronaphthalene, bicyclo[4.2.0]oct-3-ene, naphthalene and adamantane. Exemplary fused carbocycles include decalin, naphthalene, 1,2,3,4-tetrahydronaphthalene, bicyclo[4.2.0]octane, 4,5,6,7-tetrahydro-lH-indene and

[0062] bicyclo [4.1.0]hept-3-ene. “Carbocycles” may be substituted at any one or more positions capable of bearing a hydrogen atom.

[0063] The term “carbocyclylalkyl”, as used herein, refers to an alkyl group substituted with a carbocycle group.

[0064] The term “carbonate” is art-recognized and refers to a group -OCO2-.

[0065] The term “carboxy”, as used herein, refers to a group represented by the formula -CO2H. The term “cycloalkyl” includes substituted or unsubstituted non-aromatic single ring structures, preferably 4- to 8-membered rings, more preferably 4- to 6-membered rings. The term “cycloalkyl” also includes polycyclic ring systems having two or more cyclic rings in which two or more carbons are common to two adjoining rings wherein at least one of the rings is cycloalkyl and the substituent (e.g., R100) is attached to the cycloalkyl ring, e.g., the other cyclic rings can be cycloalkyls, cycloalkenyls, cycloalkynyls, aryls, heteroaryls, and / or heterocyclyls.

[0066] The term “ester”, as used herein, refers to a group -C(O)OR9wherein R9represents a hydrocarbyl group.

[0067] The term “ether”, as used herein, refers to a hydrocarbyl group linked through an oxygen to another hydrocarbyl group. Accordingly, an ether substituent of a hydrocarbyl group may be hydrocarbyl-O-. Ethers may be either symmetrical or unsymmetrical. Examples of ethers include, but are not limited to, heterocycle-O-heterocycle and aryl-O-heterocycle. Ethers include “alkoxyalkyl” groups, which may be represented by the general formula alkyl-O-alkyl.

[0068] The terms “halo” and “halogen” as used herein means halogen and includes chloro, fluoro, bromo, and iodo.

[0069] The terms “hetaralkyl” and “heteroaralkyl”, as used herein, refers to an alkyl group substituted with a hetaryl group.

[0070] The terms “heteroaryl” and “hetaryl” include substituted or unsubstituted aromatic single ring structures, preferably 5- to 7-membered rings, more preferably 5- to 6-membered rings, whose ring structures include at least one heteroatom, preferably one to four heteroatoms, more preferably one or two heteroatoms. The terms “heteroaryl” and “hetaryl” also include polycyclic ring systems having two or more cyclic rings in which two or more carbons are common to two adjoining rings wherein at least one of the rings is heteroaromatic, e.g., the other cyclic rings can be cycloalkyls, cycloalkenyls, cycloalkynyls, aryls, heteroaryls, and / or heterocyclyls. Heteroaryl groups include, for example, pyrrole, furan, thiophene, imidazole, oxazole, thiazole, pyrazole, pyridine, pyrazine, pyridazine, and pyrimidine, and the like.

[0071] The term “heteroatom” as used herein means an atom of any element other than carbon or hydrogen. Preferred heteroatoms are nitrogen, oxygen, and sulfur.

[0072] The term “heterocyclylalkyl”, as used herein, refers to an alkyl group substituted with a heterocycle group.

[0073] The terms “heterocyclyl”, “heterocycle”, and “heterocyclic” refer to substituted or unsubstituted non-aromatic ring structures, preferably 3- to 10-membered rings, more preferably 3- to 7-membered rings, whose ring structures include at least one heteroatom, preferably one to four heteroatoms, more preferably one or two heteroatoms. The terms “heterocyclyl” and “heterocyclic” also include polycyclic ring systems having two or more cyclic rings in which two or more carbons are common to two adjoining rings wherein at least one of the rings is heterocyclic, e.g., the other cyclic rings can be cycloalkyls, cycloalkenyls, cycloalkynyls, aryls, heteroaryls, and / or heterocyclyls. Heterocyclyl groups include, for example, piperidine, piperazine, pyrrolidine, morpholine, lactones, lactams, and the like.

[0074] The term “hydrocarbyl”, as used herein, refers to a group that is bonded through a carbon atom that does not have a =0 or =S substituent, and typically has at least one carbon-hydrogen bond and a primarily carbon backbone, but may optionally include heteroatoms. Thus, groups like methyl, ethoxyethyl, 2-pyridyl, and even trifluoromethyl are considered to be hydrocarbyl for the purposes of this application, but substituents such as acetyl (which has a =0 substituent on the linking carbon) and ethoxy (which is linked through oxygen, not carbon) are not.

[0075] Hydrocarbyl groups include, but are not limited to aryl, heteroaryl, carbocycle, heterocycle, alkyl, alkenyl, alkynyl, and combinations thereof.

[0076] The term “hydroxyalkyl”, as used herein, refers to an alkyl group substituted with a hydroxy group.

[0077] The term “lower” when used in conjunction with a chemical moiety, such as, acyl, acyloxy, alkyl, alkenyl, alkynyl, or alkoxy is meant to include groups where there are ten or fewer atoms in the substituent, preferably six or fewer. A “lower alkyl”, for example, refers to an alkyl group that contains ten or fewer carbon atoms, preferably six or fewer. In certain embodiments, acyl, acyloxy, alkyl, alkenyl, alkynyl, or alkoxy substituents defined herein are respectively lower acyl, lower acyloxy, lower alkyl, lower alkenyl, lower alkynyl, or lower alkoxy, whether they appear alone or in combination with other substituents, such as in the recitations hydroxyalkyl and aralkyl (in which case, for example, the atoms within the aryl group are not counted when counting the carbon atoms in the alkyl substituent).

[0078] The terms “polycyclyl”, “polycycle”, and “polycyclic” refer to two or more rings (e.g., cycloalkyls, cycloalkenyls, cycloalkynyls, aryls, heteroaryls, and / or heterocyclyls) in which two or more atoms are common to two adjoining rings, e.g., the rings are “fused rings”. Each of the rings of the polycycle can be substituted or unsubstituted. In certain embodiments, each ring of the poly cycle contains from 3 to 10 atoms in the ring, preferably from 5 to 7.

[0079] The term “sulfate” is art-recognized and refers to the group –OSO₃H, or a pharmaceutically acceptable salt thereof.

[0080] The term “sulfonamide” is art-recognized and refers to the group represented by the general formulae

[0081]

[0082] wherein R9and R10independently represent hydrogen or hydrocarbyl.

[0083] The term “sulfoxide” is art-recognized and refers to the group-S(O)-.

[0084] The term “sulfonate” is art-recognized and refers to the group SO₃H, or a pharmaceutically acceptable salt thereof.

[0085] The term “sulfone” is art-recognized and refers to the group –S(O)₂–.

[0086] The term “substituted” refers to moieties having substituents replacing a hydrogen on one or more carbons of the backbone. It will be understood that “substitution” or “substituted with” includes the implicit proviso that such substitution is in accordance with permitted valence of the substituted atom and the substituent, and that the substitution results in a stable compound, e.g., which does not spontaneously undergo transformation such as by rearrangement, cyclization, elimination, etc. As used herein, the term “substituted” is contemplated to include all permissible substituents of organic compounds. In a broad aspect, the permissible substituents include acyclic and cyclic, branched and unbranched, carbocyclic and heterocyclic, aromatic and non-aromatic substituents of organic compounds. The permissible substituents can be one or more and the same or different for appropriate organic compounds. For purposes of this disclosure, the heteroatoms such as nitrogen may have hydrogen substituents and / or any permissible substituents of organic compounds described herein which satisfy the valences of the heteroatoms. Substituents can include any substituents described herein, for example, a halogen, a hydroxy, a carbonyl (such as a carboxyl, an alkoxycarbonyl, a formyl, or an acyl), a thiocarbonyl (such as a thioester, a thioacetate, or a thioformate), an alkoxy, a phosphoryl, a phosphate, a phosphonate, a phosphinate, an amino, an amido, an amidine, an imine, a cyano, a nitro, an azido, a sulfhydryl, an alkylthio, a sulfate, a sulfonate, a sulfamoyl, a sulfonamido, a sulfonyl, a heterocyclyl, an aralkyl, or an aromatic or heteroaromatic moiety. It will be understood by those skilled in the art that the moieties substituted on the hydrocarbon chain can themselves be substituted, if appropriate.

[0087] The term “thioalkyl”, as used herein, refers to an alkyl group substituted with a thiol group.

[0088] The term “thioester”, as used herein, refers to a group -C(O)SR9or -SC(O)R9wherein R9represents a hydrocarbyl.

[0089] The term “thioether”, as used herein, is equivalent to an ether, wherein the oxygen is replaced with a sulfur.

[0090] The term “urea” is art-recognized and may be represented by the general formula

[0091]

[0092] wherein R9and R10independently represent hydrogen or a hydrocarbyl.

[0093] Some of the compounds useful in the methods and compositions of this disclosure have at least one stereogenic center in their structure. This stereogenic center may be present in a R or a S configuration, said R and S notation is used in correspondence with the rules described in Pure Appl. Chem. (1976), 45, 11-30. The disclosure contemplates all stereoisomeric forms such as enantiomeric and diastereoisomeric forms of the compounds, salts, prodrugs or mixtures thereof (including all possible mixtures of stereoisomers). See, e.g., WO 01 / 062726.

[0094] Furthermore, certain compounds which contain alkenyl groups may exist as Z (zusammen) or E (entgegen) isomers. In each instance, the disclosure includes both mixture and separate individual isomers.

[0095] Some of the compounds may also exist in tautomeric forms. Such forms, although not explicitly indicated in the formulae described herein, are intended to be included within the scope of the present disclosure.

[0096] The term “Log of solubility”, “LogS” or “logS” as used herein is used in the art to quantify the aqueous solubility of a compound. The aqueous solubility of a compound significantly affects its absorption and distribution characteristics. A low solubility often goes along with a poor absorption. LogS value is a unit stripped logarithm (base 10) of the solubility measured in mol / liter.

[0097] The term “weight average molecular weight,” also abbreviated in some instances as Mw, as used herein refers to the sum of the molecular weights of each polymer chain in a mixture of polymer chains, divided by the total number of chains in the mixture.

[0098] The term “glass transition temperature” or “TG” as used herein refers to the temperature or range of temperatures at which a polymer or mixture of polymers undergoes a phase transition from a “glassy” or amorphous solid state to a viscous liquid or semi-liquid state. In some embodiments, this transition may also be characterized by a decrease in the brittle nature of the glassy material.

[0099] The term “decomposition temperature” as used herein refers to the temperature at which a substance, e.g., a polymer of the disclosure, begins to decompose or undergo a chemical change to the composition of the substance.

[0100] The terms "statistical mixture" and "statistical copolymer" refer to copolymers in which the sequential distribution of the monomeric units obeys known statistical laws, e.g., the monomer sequence distribution may follow Markovian statistics of zeroth (Bernoullian), first, second, or higher order. The elementary processes leading to the formation of a statistical sequence of monomeric units do not necessarily proceed with equal a priori probability. These processes may, in some embodiments, lead to various types of sequence distribution comprising those in which the arrangement of monomeric units tends toward alternation, tends toward clustering of like units, or exhibits no ordering tendency at all. These terms may be used interchangeably herein.

[0101] As used herein, the term “Monomer” may refer to a sub-unit which is either present in a precursor form (e.g., a dihalide-substituted precursor) or is incorporated into a polymer’s structure (e.g., units of Formula I may be referred to as monomers).

[0102] The term “dispersity,” (abbreviated D) is art-recognized, and is used herein is a measure of the distribution of sizes (e.g., molecular weight, chain length) in a mixture of polymers. This quantity can also be referred to as the polydispersity index, or PDI.

[0103] As used herein, the term “curing” or “cured” refer to a material that has undergone a process that results in the material taking on a form, shape, configuration, or structure that cannot be reprocessed, molded, or extruded into a different one. Such processing involves exposing said materials to certain conditions (e.g., heat, oxygen, chemical initiators) to initiate the curing process. Materials that have not been cured, or for which curing is not required, refer to materials that have not been aged for a period of time, or that have not been subjected to the conditions required to initiate and / or maintain a curing process, or for which a curing process is not complete.

[0104] As used herein, the term “fluid” refers to gases, liquids, supercritical fluids, and combinations thereof.

[0105] As used herein, the term “permeate” refers to fluid that has come into contact with a composite membrane of the disclosure, but has not been removed by, or adsorbed / absorbed to, said composite membrane. “Permeate” often refers to a fluid or mixture of fluids from which some or all of any impurities or undesired fluids have been removed.

[0106] As used herein, the term “retentate” refers to fluid (generally an impurity fluid) that has been removed by, and / or adsorbed / absorbed to, a composite membrane of the disclosure, and thereby separated from the permeate.

[0107] The term “hollow fiber,” as used herein, refers to a fiber that is substantially hollow, enclosing an inner volume. The term “fiber” is also contemplated to encompass fibers, filaments, strands, fibrils, cords, and other common terms for objects that are substantially longer than they are wide. As used herein, the term “outer diameter” refers to the diameter of a circular crosssection of the hollow fiber, wherein the edge of the circular cross-section coincides with the outermost surface of the hollow fiber.

[0108] As used herein, the term “fiber length” as used herein refers to the total length of a fiber, e.g., the hollow fibers of the disclosure.

[0109] In some embodiments, the present disclosure relates to a process for isolation of He, comprising

[0110] a) contacting a first gas separation membrane with a first gas stream comprising He and H₂, thereby producing a second gas stream comprising He and H₂;

[0111] b) contacting the second gas stream with air under conditions sufficient to combust the H₂, thereby producing a third gas stream comprising He; and

[0112] c) contacting a second gas separation membrane with the third gas stream, thereby producing a fourth gas stream comprising He.

[0113] In some embodiments, the first gas stream contacts the first separation membrane at a pressure about 1.1 bar to about 200 bar, such as about 1.1 bar to about 200 bar, about 2 bar to about 200 bar, about 5 bar to about 200 bar, about 10 bar to about 200 barsabout 20 bar to about 200 barsabout 40 bar to about 200 barsabout 60 bar to about 200 barsabout 80 bar to about 200 barsabout 100 bar to about 200 barsabout 120 bar to about 200 barsabout 140 bar to about 200 barsabout 160 bar to about 200 barsabout 180 bar to about 200 bar, about 1.1 bar to about 150 bar, such as about 1.1 bar to about 150 bar, about 2 bar to about 150 bar, about 5 bar to about 150 bar, about 10 bar to about 150 barsabout 20 bar to about 150 barsabout 40 bar to about 150 barsabout 60 bar to about 150 barsabout 80 bar to about 150 barsabout 100 bar to about 150 barsabout 120 bar to about 150 barsabout 140 bar to about 150 bars1.1 bar to about 100 bar, such as about 1.1 bar to about 100 bar, about 2 bar to about 100 bar, about 5 bar to about 100 bar, about 10 bar to about 100 barsabout 20 bar to about 100 barsabout 40 bar to about 100 barsabout 60 bar to about 100 barsabout 80 bar to about 100 barsabout 2 bar to about 10 barsabout 5 bar to about 20 barsabout 10 bar to about 50 bar, about 20 bar to about 60 bar, or about 20 bar to about 80 bar. In some embodiments, the first gas stream contacts the first separation membrane at a pressure about 100 bar to about 140 bar. In some embodiments, the first gas stream contacts the first separation membrane at a pressure about 1.1 bar, about 2 bar, about 5 bar, about 10 bar, about 20 bar, about 30 bar, about 40 bar, about 50 bar, about 60 bar, about 70 bar, about 80 bar, about 90 bar, about 100 bar, about 110 bar, about 120 bar, about 130 bar, about 140 bar, about 150 bar, about 160 bar, about 170 bar, about 180 bar, about 190 bar, about 200 bar.

[0114] In some embodiments, the first gas stream contacts the first separation membrane at a temperature about 15 °C to about 80 °C, such as about 20 °C to about 80 °C, about 25 °C to about 80 °C, about 30 °C to about 80 °C, about 35 °C to about 80 °C, about 40 °C to about 80 °C, about 45 °C to about 80 °C, about 50 °C to about 80 °C, about 55 °C to about 80 °C, about 60 °C to about 80 °C, about 65 °C to about 80 °C, about 70 °C to about 80 °C, about 75 °C to about 80 °C, about 15 °C to about 60 °C, such as about 20 °C to about 60 °C, about 25 °C to about 60 °C, about 30 °C to about 60 °C, about 35 °C to about 60 °C, about 40 °C to about 60 °C, about 45 °C to about 60 °C, about 50 °C to about 60 °C, about 55 °C to about 60 °C, about 15 °C to about 40 °C, such as about 20 °C to about 40 °C, about 25 °C to about 40 °C, about 30 °C to about 40 °C, about 35 °C to about 40 °C, about 15 °C to about 30 °C, such as about 20 °C to about 30 °C, or about 25 °C to about 30 °C. In some embodiments, the first gas stream contacts the first separation membrane at a temperature about 15 °C, about 20 °C, about 25 °C, about 30 °C, about 35 °C, about 40 °C, about 45 °C, about 50 °C, about 55 °C, about 60 °C, about 65 °C, about 70 °C, about 75 °C, or about 80 °C. In some embodiments, the first gas stream contacts the first separation membrane at a temperature about 25 °C to about 50 °C. In some embodiments, the first gas stream contacts the first separation membrane at a temperature about 35 °C.

[0115] In some embodiments, the process further comprises pressurizing the third gas stream prior to contacting with the second gas separation membrane. In some embodiments, the third gas stream is pressurized to a pressure about 1.1 bar to about 200 bar, such as about 1.1 bar to about 200 bar, about 2 bar to about 200 bar, about 5 bar to about 200 bar, about 10 bar to about 200 barsabout 20 bar to about 200 barsabout 40 bar to about 200 barsabout 60 bar to about 200 barsabout 80 bar to about 200 barsabout 100 bar to about 200 barsabout 120 bar to about 200 barsabout 140 bar to about 200 barsabout 160 bar to about 200 barsabout 180 bar to about 200 bar, about 1.1 bar to about 150 bar, such as about 1.1 bar to about 150 bar, about 2 bar to about 150 bar, about 5 bar to about 150 bar, about 10 bar to about 150 barsabout 20 bar to about 150 barsabout 40 bar to about 150 barsabout 60 bar to about 150 barsabout 80 bar to about 150 barsabout 100 bar to about 150 barsabout 120 bar to about 150 barsabout 140 bar to about 150 bars1.1 bar to about 100 bar, such as about 1.1 bar to about 100 bar, about 2 bar to about 100 bar, about 5 bar to about 100 bar, about 10 bar to about 100 barsabout 20 bar to about 100 barsabout 40 bar to about 100 barsabout 60 bar to about 100 barsabout 80 bar to about 100 barsabout 2 bar to about 10 barsabout 5 bar to about 20 barsabout 10 bar to about 50 bar, about 20 bar to about 60 bar, or about 20 bar to about 80 bar. In some embodiments, the third gas stream is pressurized to a pressure about 1.1 bar, about 2 bar, about 5 bar, about 10 bar, about 20 bar, about 30 bar, about 40 bar, about 50 bar, about 60 bar, about 70 bar, about 80 bar, about 90 bar, about 100 bar, about 110 bar, about 120 bar, about 130 bar, about 140 bar, about 150 bar, about 160 bar, about 170 bar, about 180 bar, about 190 bar, about 200 bar.

[0116] In some embodiments, the third gas stream contacts the second gas separation membrane at a temperature about 15 °C to about 80 °C, such as about 20 °C to about 80 °C, about 25 °C to about 80 °C, about 30 °C to about 80 °C, about 35 °C to about 80 °C, about 40 °C to about 80 °C, about 45 °C to about 80 °C, about 50 °C to about 80 °C, about 55 °C to about 80 °C, about 60 °C to about 80 °C, about 65 °C to about 80 °C, about 70 °C to about 80 °C, about 75 °C to about 80 °C, about 15 °C to about 60 °C, such as about 20 °C to about 60 °C, about 25 °C to about 60 °C, about 30 °C to about 60 °C, about 35 °C to about 60 °C, about 40 °C to about 60 °C, about 45 °C to about 60 °C, about 50 °C to about 60 °C, about 55 °C to about 60 °C, about 15 °C to about 40 °C, such as about 20 °C to about 40 °C, about 25 °C to about 40 °C, about 30 °C to about 40 °C, about 35 °C to about 40 °C, about 15 °C to about 30 °C, such as about 20 °C to about 30 °C, or about 25 °C to about 30 °C. In some embodiments, the third gas stream contacts the second gas separation membrane at a temperature about 15 °C, about 20 °C, about 25 °C, about 30 °C, about 35 °C, about 40 °C, about 45 °C, about 50 °C, about 55 °C, about 60 °C, about 65 °C, about 70 °C, about 75 °C, or about 80 °C. In some embodiments, the third gas stream contacts the second gas separation membrane at a temperature about 25 °C to about 50 °C. In some embodiments, the third gas stream contacts the second gas separation membrane at a temperature about 35 °C.

[0117] In some embodiments, combusting the H₂ comprises releasing energy, and pressurizing the third gas stream comprises consuming the energy. In some embodiments, the first gas stream comprises about 0.1 vol. % to about 50 vol. % He. In some embodiments, the first gas stream comprises about 0.1 vol. % to about 30 vol. % He. In some embodiments, the first gas stream comprises about 0.5 vol. % to about 10 vol. % He. In some embodiments, the first gas stream comprises about 0.8 vol. % to about 4 vol. % He. For example, in some embodiments the first gas stream comprises about 0.1 vol. % to about 50 vol. %, about 0.2 vol. % to about 50 vol. %, about 0.5 vol. % to about 50 vol. %, about 0.8 vol. % to about 50 vol. %, about 1 vol. % to about 50 vol. %, about 2 vol. % to about 50 vol. %, about 5 vol. % to about 50 vol. %, about 7 vol. % to about 50 vol. %, about 10 vol. % to about 50 vol. %, about 15 vol. % to about 50 vol. %, about 20 vol. % to about 50 vol. %, about 25 vol. % to about 50 vol. %, about 30 vol. % to about 50 vol. %, about 35 vol. % to about 50 vol. %, about 40 vol. % to about 50 vol. %, about 45 vol. % to about 50 vol. %, about 0.1 vol. % to about 40 vol. %, about 0.2 vol. % to about 40 vol. %, about 0.5 vol. % to about 40 vol. %, about 0.8 vol. % to about 40 vol. %, about 1 vol. % to about 40 vol. %, about 2 vol. % to about 40 vol. %, about 5 vol. % to about 40 vol. %, about 7 vol. % to about 40 vol. %, about 10 vol. % to about 40 vol. %, about 15 vol. % to about 40 vol. %, about 20 vol. % to about 40 vol. %, about 25 vol. % to about 40 vol. %, about 30 vol. % to about 40 vol. %, about 35 vol. % to about 40 vol. %, about 0.1 vol. % to about 30 vol. %, about 0.2 vol. % to about 30 vol. %, about 0.5 vol. % to about 30 vol. %, about 0.8 vol. % to about 30 vol. %, about 1 vol. % to about 30 vol. %, about 2 vol. % to about 30 vol. %, about 5 vol. % to about 30 vol. %, about 7 vol. % to about 30 vol. %, about 10 vol. % to about 30 vol. %, about 15 vol. % to about 30 vol. %, about 20 vol. % to about 30 vol. %, about 25 vol. % to about 30 vol. %, about 0.1 vol. % to about 30 vol. %, about 0.2 vol. % to about 30 vol. %, about 0.5 vol. % to about 30 vol. %, about 0.8 vol. % to about 30 vol. %, about 1 vol. % to about 30 vol. %, about 2 vol. % to about 30 vol. %, about 5 vol. % to about 30 vol. %, about 7 vol. % to about 30 vol. %, about 10 vol. % to about 30 vol. %, about 15 vol. % to about 30 vol. %, about 0.1 vol. % to about 20 vol. %, about 0.2 vol. % to about 20 vol. %, about 0.5 vol. % to about 20 vol. %, about 0.8 vol. % to about 20 vol. %, about 1 vol. % to about 20 vol. %, about 2 vol. % to about 20 vol. %, about 5 vol. % to about 20 vol. %, about 7 vol. % to about 20 vol. %, about 10 vol. % to about 20 vol. %, about 15 vol. % to about 20 vol. %, about 0.1 vol. % to about 10 vol. %, about 0.2 vol. % to about 10 vol. %, about 0.5 vol. % to about 10 vol. %, about 0.8 vol. % to about 10 vol. %, about 1 vol. % to about 10 vol. %, about 2 vol. % to about 10 vol. %, about 5 vol. % to about 10 vol. %, about 7 vol. % to about 10 vol. %, about 0.1 vol. % to about 7 vol. %, about 0.2 vol. % to about 7 vol. %, about 0.5 vol. % to about 7 vol. %, about 0.8 vol. % to about 7 vol. %, about 1 vol. % to about 7 vol. %, about 2 vol. % to about 7 vol. %, about 5 vol. % to about 7 vol. %, about 0.1 vol. % to about 5 vol. %, about 0.2 vol. % to about 5 vol. %, about 0.5 vol. % to about 5 vol. %, about 0.8 vol. % to about 5 vol. %, about 1 vol. % to about 5 vol. %, about 2 vol. % to about 5 vol. %, about 0.1 vol. % to about 2 vol. %, about 0.2 vol. % to about 2 vol. %, about 0.5 vol. % to about 2 vol. %, about 0.8 vol. % to about 2 vol. %, about 1 vol. % to about 2 vol. %, about 0.1 vol. % to about 1 vol. %, about 0.2 vol. % to about 1 vol. %, about 0.5 vol. % to about 1 vol. %, or about 0.8 vol. % to about 1 vol. % of He. In some embodiments, the first gas stream comprises about 0.1 vol. %, about 0.2 vol. %, about 0.5 vol. %, about 0.8 vol. %, about 1 vol. %, about 1.2 vol. %, about 1.5 vol. %, about 1.7 vol. %, about 2.0 vol. %, about 2.2 vol. %, about 2.5 vol. %, about 2.7 vol. %, about 3 vol. %, about 3.2 vol. %, about 3.5 vol. %, about 3.7 vol. %, about 3.9 vol. %, about 4.2 vol. %, about 4.5 vol. %, about 4.7 vol. %, about 5 vol. %, about 7 vol. %, about 10 vol. %, about 15 vol. %, about 20 vol. %, about 25 vol. %, about 30 vol. %, about 35 vol. %, about 40 vol. %, about 45 vol. %, or about 50 vol. % of He. In some embodiments the first gas stream comprises about 0.8 vol. % to about 3.9 vol. % of He.

[0118] In some embodiments, the first gas stream comprises about 1 vol. % to about 70 vol. % H2. In some embodiments the first gas stream comprises about 2 vol. % to about 50 vol. % H2. In some embodiments the first gas stream comprises about 5 vol. % to about 30 vol. % H2. In some embodiments, the first gas stream comprises about 1 vol. % to about 50 vol. % H2. For example, in some embodiments the first gas stream comprises about 1 vol. % to about 70 vol. %, about 2 vol. % to about 70 vol. %, about 5 vol. % to about 70 vol. %, about 7 vol. % to about 70 vol. %, about 10 vol. % to about 70 vol. %, about 15 vol. % to about 70 vol. %, about 20 vol. % to about 70 vol. %, about 25 vol. % to about 70 vol. %, about 30 vol. % to about 70 vol. %, about 35 vol. % to about 70 vol. %, about 40 vol. % to about 70 vol. %, about 45 vol. % to about 70 vol. %, about 50 vol. % to about 70 vol. %, about 55 vol. % to about 70 vol. %, about 60 vol. % to about 70 vol. %, or about 65 vol. % to about 70 vol. % H2. In some embodiments, the first gas stream comprises about 1 vol. % to about 60 vol. %, about 2 vol. % to about 60 vol. %, about 5 vol. % to about 60 vol. %, about 7 vol. % to about 60 vol. %, about 10 vol. % to about 60 vol. %, about 15 vol. % to about 60 vol. %, about 20 vol. % to about 60 vol. %, about 25 vol. % to about 60 vol. %, about 30 vol. % to about 60 vol. %, about 35 vol. % to about 60 vol. %, about 40 vol. % to about 60 vol. %, about 45 vol. % to about 60 vol. %, about 50 vol. % to about 60 vol. %, or about 55 vol. % to about 60 vol. % H2. In some embodiments, the first gas stream comprises about 1 vol. % to about 50 vol. %, about 2 vol. % to about 50 vol. %, about 5 vol. % to about 50 vol. %, about 7 vol. % to about 50 vol. %, about 10 vol. % to about 50 vol. %, about 15 vol. % to about 50 vol. %, about 20 vol. % to about 50 vol. %, about 25 vol. % to about 50 vol. %, about 30 vol. % to about 50 vol. %, about 35 vol. % to about 50 vol. %, about 40 vol. % to about 50 vol. %, or about 45 vol. % to about 50 vol. % H2. In some embodiments, the first gas stream comprises about 1 vol. % to about 40 vol. %, about 2 vol. % to about 40 vol. %, about 5 vol. % to about 40 vol. %, about 7 vol. % to about 40 vol. %, about 10 vol. % to about 40 vol. %, about 15 vol. % to about 40 vol. %, about 20 vol. % to about 40 vol. %, about 25 vol. % to about 40 vol. %, about 30 vol. % to about 40 vol. %, or about 35 vol. % to about 40 vol. % H2. In some embodiments, the first gas stream comprises about 1 vol. % to about 30 vol. %, about 2 vol. % to about 30 vol. %, about 5 vol. % to about 30 vol. %, about 7 vol. % to about 30 vol. %, about 10 vol. % to about 30 vol. %, about 15 vol. % to about 30 vol. %, about 20 vol. % to about 30 vol. %, or about 25 vol. % to about 30 vol. % H2. In some embodiments, the first gas stream comprises about 1 vol. % to about 20 vol. %, about 2 vol. % to about 20 vol. %, about 5 vol. % to about 20 vol. %, about 7 vol. % to about 20 vol. %, about 10 vol. % to about 20 vol. %, or about 15 vol. % to about 20 vol. % H2. In some embodiments, the first gas stream comprises about 1 vol. % to about 10 vol. %, about 2 vol. % to about 10 vol. %, about 5 vol. % to about 10 vol. %, or about 7 vol. % to about 10 vol. % H2. In some embodiments, the first gas stream comprises about 1 vol. % to about 15 vol. %, about 2 vol. % to about 15 vol. %, about 5 vol. % to about 15 vol. %, or about 7 vol. % to about 15 vol. % H2. In some embodiments, the first gas stream comprises about 1 vol. % to about 7 vol. %, about 2 vol. % to about 7 vol. %, or about 5 vol. % to about 7 vol. % H2. In some embodiments, the first gas stream comprises about 1 vol. % to about 5 vol. % or about 2 vol. % to about 5 vol. % H2. In some embodiments, the first gas stream comprises about 1 vol. % to about 2 vol. % H2. In some embodiments, the first gas stream comprises about 1 vol. %, about 1.2 vol. %, about 1.5 vol. %, about 1.7 vol. %, about 2.0 vol. %, about 2.2 vol. %, about 2.5 vol. %, about 2.7 vol. %, about 3 vol. %, about 3.2 vol. %, about 3.5 vol. %, about 3.7 vol. %, about 3.9 vol. %, about 4.2 vol. %, about 4.5 vol. %, about 4.7 vol. %, about 5 vol. %, about 7 vol. %, about 10 vol. %, about 15 vol. %, about 20 vol. %, about 25 vol. %, about 30 vol. %, about 35 vol. %, about 40 vol. %, about 45 vol. %, about 50 vol. %, about 55 vol. %, about 60 vol. %, about 65 vol. %, or about 70 vol. % of H2. In some embodiments the first gas stream comprises about 5 vol. % to about 27 vol. % of H2.

[0119] In some embodiments, the fourth gas stream comprises about 50 vol. % to about 100 vol. % He. In some embodiments, the fourth gas stream comprises about 75 vol. % to about 100 vol. % He. In some embodiments, the fourth gas stream comprises about 80 vol. % to about 99 vol. % He. In some embodiments, the fourth gas stream comprises about 95 vol. % to about 99 vol. % He. In some embodiments, the fourth gas stream comprises about 50 vol. % to about 100 vol. % He. In some embodiments, the fourth gas stream comprises about 60 vol. % to about 100 vol. % He. In some embodiments, the fourth gas stream comprises about 70 vol. % to about 95 vol. % He. In some embodiments, the fourth gas stream comprises about 80 vol. % to about 100 vol. % He. For example, in some embodiments the fourth gas stream comprises about 50 vol. % to about 100 vol. %, about 55 vol. % to about 100 vol. %, about 60 vol. % to about 100 vol. %, about 65 vol. % to about 100 vol. %, about 70 vol. % to about 100 vol. %, about 75 vol. % to about 100 vol. %, about 80 vol. % to about 100 vol. %, about 85 vol. % to about 100 vol. %, about 90 vol. % to about 100 vol. %, about 95 vol. % to about 100 vol. %, about 50 vol. % to about 90 vol. %, about 55 vol. % to about 90 vol. %, about 60 vol. % to about 90 vol. %, about 65 vol. % to about 90 vol. %, about 70 vol. % to about 90 vol. %, about 75 vol. % to about 90 vol. %, about 80 vol. % to about 90 vol. %, about 85 vol. % to about 90 vol. %, about 50 vol. % to about 80 vol. %, about 55 vol. % to about 80 vol. %, about 60 vol. % to about 80 vol. %, about 65 vol. % to about 80 vol. %, about 70 vol. % to about 80 vol. %, about 75 vol. % to about 80 vol. %, about 50 vol. % to about 70 vol. %, about 55 vol. % to about 70 vol. %, about 60 vol. % to about 70 vol. %, about 65 vol. % to about 70 vol. %, about 50 vol. % to about 60 vol. %, about 55 vol. % to about 60 vol. %, about 50 vol. % to about 55 vol. %, about 60 vol. % to about 95 vol. %, about 65 vol. % to about 95 vol. %, about 70 vol. % to about 95 vol. %, about 75 vol. % to about 95 vol. %, about 80 vol. % to about 95 vol. %, about 85 vol. % to about 95 vol. %, about 90 vol. % to about 95 vol. %, about 60 vol. % to about 85 vol. %, about 65 vol. % to about 85 vol. %, about 70 vol. % to about 85 vol. %, about 75 vol. % to about 85 vol. %, about 80 vol. % to about 85 vol. %, about 60 vol. % to about 75 vol. %, about 65 vol. % to about 75 vol. %, about 70 vol. % to about 75 vol. %, about 60 vol. % to about 70 vol. %, or about 65 vol. % to about 70 vol. % of He. In some embodiments, the fourth gas stream comprises about 80 vol. % to about 100 vol. %, about 82 vol. % to about 100 vol. %, about 85 vol. % to about 100 vol. %, about 87 vol. % to about 100 vol. %, about 90 vol. % to about 100 vol. %, about 92 vol. % to about 100 vol. %, about 95 vol. % to about 100 vol. %, about 96 vol. % to about 100 vol. %, about 97 vol. % to about 100 vol. %, about 98 vol. % to about 100 vol. %, about 99 vol. % to about 100 vol. %, about 95 vol. % to about 99 vol. %, about 96 vol. % to about 99 vol. %, about 97 vol. % to about 99 vol. %, about 98 vol. % to about 99 vol. %, about 99 vol. % to about 100 vol. %, about 80 vol. % to about 95 vol. %, about 82 vol. % to about 95 vol. %, about 85 vol. % to about 95 vol. %, about 87 vol. % to about 95 vol. %, about 90 vol. % to about 95 vol. %, about 80 vol. % to about 90 vol. %, about 82 vol. % to about 90 vol. %, about 85 vol. % to about 90 vol. %, about 87 vol. % to about 90 vol. %, about 80 vol. % to about 85 vol. %, about 82 vol. % to about 85 vol. %, about 80 vol. % to about 82 vol. %, or about 80 vol. % to about 81 vol. % of He. In some embodiments, the fourth gas stream comprises about 50 vol. %, about 55 vol. %, about 60 vol. %, about 65 vol. %, about 70 vol. %, about 75 vol. %, about 80 vol. %, about 82 vol. %, about 85 vol. %, about 87 vol. %, about 90 vol. %, about 92 vol. %, about 95 vol. %, about 97 vol. %, about 98 vol. %, about 99 vol. %, or about 100 vol. % of He. In some embodiments the fourth gas stream comprises about 80 vol. % to about 99 vol. % of He.

[0120] Composite Membranes

[0121] In certain aspects, provided herein are composite membranes comprising:

[0122] a mesoporous membrane support layer comprising a plurality of pores extending through the support layer, said support layer having a first side, a second side, and a thickness; and optionally, a gutter layer comprising a permeable elastic polymer, said gutter layer having a first side, a second side, and a thickness;

[0123] a thin film membrane selective layer comprising a plurality of polymer chains, said selective layer having a first side, a second side, and a thickness;

[0124] wherein:

[0125] the composite membrane is in the form of a hollow fiber; when the gutter layer is present, the second side of the support layer is disposed along the first side of the gutter layer, and the second side of the gutter layer is disposed along the first side of the selective layer;

[0126] when the gutter layer is absent, the second side of the support layer is disposed along the first side of the selective layer; and

[0127] the thickness of the selective layer is less than about 10 microns.

[0128] In certain embodiments, the thickness of the selective layer is from about 0.1 to about 10 microns. In further embodiments, the thickness of the selective layer is from about 0.1 to about 5 microns. In yet further embodiments, the thickness of the selective layer is from about 0.5 to about 1.5 microns.

[0129] In certain embodiments, the thickness of the selective layer is about 0.1 microns. In further embodiments, the thickness of the selective layer is about 0.2 microns. In yet further embodiments, the thickness of the selective layer is about 0.3 microns. In still further embodiments, the thickness of the selective layer is about 0.4 microns. In certain embodiments, the thickness of the selective layer is about 0.5 microns. In further embodiments, the thickness of the selective layer is about 0.6 microns. In yet further embodiments, the thickness of the selective layer is about 0.7 microns. In still further embodiments, the thickness of the selective layer is about 0.8 microns. In certain embodiments, the thickness of the selective layer is about

[0130] 0.9 microns.

[0131] In certain embodiments, the thickness of the selective layer is about 1 micron. In further embodiments, the thickness of the selective layer is about 2 microns. In yet further embodiments, the thickness of the selective layer is about 3 microns. In still further embodiments, the thickness of the selective layer is about 4 microns. In certain embodiments, the thickness of the selective layer is about 5 microns. In further embodiments, the thickness of the selective layer is about 6 microns. In yet further embodiments, the thickness of the selective layer is about 7 microns. In still further embodiments, the thickness of the selective layer is about 8 microns. In certain embodiments, the thickness of the selective layer is about 9 microns.

[0132] In certain embodiments, the thickness of the selective layer is less than about 10 microns. In further embodiments, the thickness of the selective layer is less than about 9 microns. In yet further embodiments, the thickness of the selective layer is less than about 8 microns. In still further embodiments, the thickness of the selective layer is less than about 7 microns. In certain embodiments, the thickness of the selective layer is less than about 6 microns. In further embodiments, the thickness of the selective layer is less than about 5 microns. In yet further embodiments, the thickness of the selective layer is less than about 4 microns. In still further embodiments, the thickness of the selective layer is less than about 3 microns. In certain embodiments, the thickness of the selective layer is less than about 2 microns. In further embodiments, the thickness of the selective layer is less than about 1 micron.

[0133] In certain embodiments, the thickness of the selective layer is less than about

[0134] 0.9 microns. In further embodiments, the thickness of the selective layer is less than about 0.8 microns. In yet further embodiments, the thickness of the selective layer is less than about 0.7 microns. In still further embodiments, the thickness of the selective layer is less than about 0.6 microns. In certain embodiments, the thickness of the selective layer is less than about 0.5 microns. In further embodiments, the thickness of the selective layer is less than about 0.4 microns. In yet further embodiments, the thickness of the selective layer is less than about 0.3 microns. In still further embodiments, the thickness of the selective layer is less than about 0.2 microns.

[0135] In certain embodiments, the thickness of the selective layer is selected from about 0.50 microns, 0.75 microns, about 1.0 micron, 1.25 microns, about 1.5 microns, about

[0136] 1.75 microns, about 2 microns, about 2.25 microns, about 2.5 microns, about 2.75 microns, and about 3 microns; preferably wherein the thickness of the selective layer is about 1 micron.

[0137] Membrane pore size may be determined using any suitable method known in the art, for example, scanning electron microscopy. In certain embodiments, the plurality of pores extending through the support layer have a pore size from about 2 nm to about 50 nm. In further embodiments, the plurality of pores extending through the support layer have an average pore size of about 2 nm. In yet further embodiments, the plurality of pores extending through the support layer have an average pore size of about 5 nm. In still further embodiments, the plurality of pores extending through the support layer have an average pore size of about 10 nm. In certain embodiments, the plurality of pores extending through the support layer have an average pore size of about 20 nm. In further embodiments, the plurality of pores extending through the support layer have an average pore size of about 30 nm. In yet further embodiments, the plurality of pores extending through the support layer have an average pore size of about 40 nm. In still further embodiments, the plurality of pores extending through the support layer have an average pore size of about 50 nm.

[0138] In certain embodiments, the thickness of the support layer is from about 15 microns to about 200 microns. In further embodiments, the thickness of the support layer is about

[0139] 15 microns. In yet further embodiments, the thickness of the support layer is about 30 microns. In still further embodiments, the thickness of the support layer is about 45 microns. In certain embodiments, the thickness of the support layer is about 60 microns. In further embodiments, the thickness of the support layer is about 75 microns. In yet further embodiments, the thickness of the support layer is about 90 microns. In still further embodiments, the thickness of the support layer is about 105 microns. In certain embodiments, the thickness of the support layer is about 120 microns. In further embodiments, the thickness of the support layer is about 135 microns. In yet further embodiments, the thickness of the support layer is about 150 microns. In still further embodiments, the thickness of the support layer is about 200 microns.

[0140] In certain embodiments, the thickness of the support layer is selected from about

[0141] 15 microns, about 30 microns, about 45 microns, about 60 microns, about 75 microns, about 90 microns, about 105 microns, about 120 microns, about 135 microns, about 150 microns, about 165 microns, about 180 microns, and about 200 microns; preferably wherein the thickness of the support layer is between about 50 and about 60 microns.

[0142] The support layer can be fabricated from one or more suitable polymers known in the art. In certain embodiments, the support layer comprises a polymer selected from polyethylenimine, polyether ether ketone, polyvinylidene difluoride, polyvinylfluoride, polytetrafluoroethylene, poly(acrylonitrile), polysulfone, cellulose acetate, poly ether sulfone, and polyimide. In further embodiments, the support layer comprises a plurality of cross-linked polymers.

[0143] The selective layer may comprise one or more suitable polymers known in the art. In certain embodiments, the plurality of polymer chains comprises norbornyl arylcyclobutene polymers. Suitable polymers are disclosed in, e.g., International Application Nos.

[0144] PCT / US2023 / 034879, filed October 11, 2023, (published as WO2024081279) and PCT / US2024 / 0f13947, filed February 01, 2024 (published as WO2024163711), both of which are expressly incorporated herein by reference in their entirety. In certain embodiments, the plurality of polymer chains is a plurality of polymer chains comprising at least one unit of Formula I, wherein Formula I consists of a subunit of Formula I’ and a subunit of Formula I”:

[0145]

[0146] (I’); (I”);

[0147] wherein:

[0148] each R1represents a connection point to the polymer;

[0149] each of the two R1groups on the subunit of Formula I’ is on an adjacent carbon to another R1group;

[0150] each R2represents a connection point between the subunit of Formula I’ and a carbon marked with an * on the subunit of Formula I’ ’;

[0151] each of the two R2groups is on an adjacent carbon to another R2group;

[0152] X is, independently at each occurrence, selected from NRA, O, S, CRBRc, S=O, and C=O;

[0153] when present, Y is, independently at each occurrence, selected from NRA, O, S, CRBRc, and C=O;

[0154] wherein, when Y is present, at least one of X and Y is CRBRcor C=O;

[0155] RAis, independently at each occurrence, selected from H, alkyl, -O-alkyl, and haloalkyl; RBand Rcare, independently at each occurrence, selected from H, OH, SH, halo, amine, alkyl, -(H)C=O, -O-alkyl, and haloalkyl;

[0156] or RBand Rc, together with the atom to which they are attached, form a cycloalkyl, cycloalkenyl, heterocycloalkenyl, or heterocycloalkyl, which is optionally substituted with one or more RG, wherein RGis selected from H, alkyl, alkoxy, and hydroxy;

[0157] n is 0 or 1; and

[0158] — represents an optional bond. In further embodiments, the plurality of polymer chains comprises polymers comprising a plurality of repeat units of Formula I. In further embodiments, the plurality of polymer chains comprises at least one unit of Formula la:

[0159]

[0160] In yet further embodiments, the plurality of polymer chains further comprises polymers further comprising another co-monomer.

[0161] Additional suitable polymers are disclosed in US Patent 9,708,443, which is expressly incorporated herein by reference in its entirety. In certain embodiments, the plurality of polymer chains is a plurality of polymer chains comprising at least one unit of Formula II:

[0162]

[0163] wherein R1, R2, R3, and R4are, independently at each occurrence, selected from H, alkyl, aryl, heterocycloalkyl, halo, a group comprising O, a group comprising O(CO), a group comprising O(CO)O, a group comprising O(CO)N, a group comprising S, a group comprising B, a group comprising NO2, a group comprising N, a group comprising P, a group comprising (PO), a group comprising CHO, a group comprising (CO), a group comprising (CO)O, a group comprising (CO)N, and a group comprising Si; and

[0164] wherein X1and X2are independently selected from -O-, -S-, -B(O)Ra-, -NRa-, -P(O)Ra-,-(PO)(O)Ra-, -CO-, -C(O)Ra(O)Rb-, and -Si(O)Ra(O)Rb-, and Raand Rbare independently selected from H, alkyl, aryl, and heterocyclyl. Further suitable polymers are disclosed in US Patent Publication No. 2022 / 0023804, which is expressly incorporated herein by reference in its entirety. In certain embodiments, the plurality of polymer chains is a plurality of polymer chains comprising at least one unit of Formula III:

[0165]

[0166] wherein:

[0167] Ar is, independently at each occurrence, selected from optionally substituted aryl;

[0168] X is selected from -O-, -S-, -B(O)Ra-, -NRa-, -P(O)Ra-, -(PO)(O)Ra-, -CO-, -CRaRb-, -C(O)Ra(O)Rb-, and -Si(O)Ra(O)Rb-;

[0169] Raand Rbare, independently at each occurrence, selected from H, alkyl, aryl, and heterocyclyl;

[0170] Ri and R2 are, independently at each occurrence, selected from H, linear or branched optionally substituted alkyl, optionally substituted alkoxy, optionally substituted aryl, heterocyclyl, halo, CHO, a group comprising O, a group comprising O(CO), a group comprising O(CO)O, a group comprising O(CO)N, a group comprising S, a group comprising B, a group comprising NO2, a group comprising N, a group comprising P, a group comprising (PO), a group comprising (CO), a group comprising (CO)O, a group comprising (CO)N, and a group comprising Si; and

[0171] n is an integer greater than 1.

[0172] Yet further suitable polymers can be found in International Patent Publication No. WO 2021 / 101659, which is expressly incorporated herein by reference in its entirety. In certain embodiments, the plurality of polymer chains is a plurality of polymer chains comprising at least one unit of Formula IV, wherein Formula IV consists of a subunit of Formula IV’ and a subunit of Formula IV”:

[0173]

[0174] wherein:

[0175] two adjacent * of IV’ are bonds to two * of IV”, and the two remaining * of IV’ are R3and R4;

[0176] X is selected from alkylene, -O-, -S-, a group comprising nitrogen, cycloalkyl, and heterocyclyl;

[0177] Y1and Y2are, independently at each occurrence, selected from alkyl;

[0178] R1, R2, R3, R4, R5, and R6are independently selected from a group comprising O, a group comprising O(CO), a group comprising O(CO)O, a group comprising O(CO)N, a group comprising S, a group comprising B, a group comprising NO2, a group comprising N, a group comprising P, a group comprising (PO), a group comprising CHO, a group comprising (CO), a group comprising (CO)O, a group comprising (CO)N, and a group comprising Si; and

[0179] XIis selected from -O-, -S-, -B(O)Ra-, -NRa-, -P(O)Ra-, -(PO)(O)Ra-, -CO-, -CRaRb-,-C(O)Ra(O)Rb-, and -Si(O)Ra(O)Rb-; and

[0180] Raand Rbare independently selected from H, alkyl, aryl, and heterocyclyl.

[0181] In certain embodiments, R1, R2, R3, R4, R5, and R6are, independently at each occurrence, selected from H, optionally substituted alkyl, optionally substituted aryl, optionally substituted heterocyclyl, halo, -ORa, -O(CO)Ra, -O(CO)ORa, — O(CO)NRaRb, -SRa, -B(O)Ra(O)Rb, -NO2, -NRaRb, -P(O)Ra(O)Rb, -PO(O)Ra(O)Rb, -CHO, -(CO)Ra, -(CO)ORa, -(CO)NRaRb, and -Si(O)Ra(O)Rb(O)Rc; wherein Ra, Rb, and Rcare, independently at each occurrence, selected from H, optionally substituted alkyl groups, optionally substituted aryl groups, and optionally substituted heterocyclyl.

[0182] Still further suitable polymers can be found in Lai, H. "Synthesis of norbornyl benzocyclobutene polymers and the transport of gases therein", Dissertation, Stanford University, August 2020 (Public Access embargoed until August 2022), which is expressly incorporated herein by reference in its entirety.

[0183] In certain embodiments, the composite membranes comprise a plurality of polymer chains, which comprise at least one unit of Formula lb:

[0184]

[0185] (lb);

[0186] wherein:

[0187] each R3is, independently at each occurrence, selected from C1-C4 alkyl, C1-C4 fluoroalkyl, halo, optionally substituted amino, and hydroxy;

[0188] each R4and R5is, independently at each occurrence, selected from H, C1-C4 alkyl, C1-C4 fluoroalkyl, halo, optionally substituted amino, and hydroxy;

[0189] A is, independently at each occurrence, selected from NRD, O, S, CRERF, S=O, and C=O; when present, B is, independently at each occurrence, selected from NRD, O, S, CRERF, and C=O;

[0190] wherein, when B is present, at least one of A and B is CRERFor C=O;

[0191] RDis, independently at each occurrence, selected from H, alkyl, -O-alkyl, or haloalkyl;

[0192] REand RFare, independently at each occurrence, selected from H, OH, SH, halo, amine, alkyl, -(H)C=O, -O-alkyl, and haloalkyl; or REand RF, together with the atom to which they are attached, form a cycloalkyl, cycloalkenyl, heterocycloalkenyl, or heterocycloalkyl, which is optionally substituted with one or more RH, wherein RHis selected from H, alkyl, alkoxy, and hydroxy;

[0193] n is 0 or 1;

[0194] each o is, independently at each occurrence, 0, 1, 2, or 3;

[0195] — represents an optional bond;

[0196] C is, independently at each occurrence, selected from:

[0197]

[0198] represents a point of attachment to the unit of Formula lb; and

[0199] D is, independently at each occurrence, a bond or selected from O, C=O, SO2, CR4R4,

[0200]

[0201] In further embodiments, the composite membranes comprise a plurality of polymer chains, which comprise at least one unit of Formula lb:

[0202]

[0203] (lb);

[0204] wherein: each R3is, independently at each occurrence, selected from C1-C4 alkyl, C1-C4 fluoroalkyl, halo, optionally substituted amino, and hydroxy;

[0205] each R4and R5is, independently at each occurrence, selected from H, C1-C4 alkyl, C1-C4 fluoroalkyl, halo, optionally substituted amino, and hydroxy;

[0206] A is, independently at each occurrence, selected from NRD, O, S, CRERF, S=O, and C=O; when present, B is, independently at each occurrence, selected from NRD, O, S, CRERF, and C=O;

[0207] wherein, when B is present, at least one of A and B is CRERFor C=O;

[0208] RDis, independently at each occurrence, selected from H, alkyl, -O-alkyl, or haloalkyl; REand RFare, independently at each occurrence, selected from H, OH, SH, halo, amine, alkyl, -(H)C=O, -O-alkyl, and haloalkyl;

[0209] or REand RF, together with the atom to which they are attached, form a cycloalkyl, cycloalkenyl, heterocycloalkenyl, or heterocycloalkyl, which is optionally substituted with one or more RH, wherein RHis selected from H, alkyl, alkoxy, and hydroxy;

[0210] optionally wherein REand RF, together with the atoms to which they are attached, form a

[0211]

[0212] n is 0 or 1;

[0213] each o is, independently at each occurrence, 0, 1, 2, or 3;

[0214] — represents an optional bond;

[0215] C is, independently at each occurrence, selected from:

[0216]

[0217] represents a point of attachment to the unit of Formula lb; and D is, independently at each occurrence, a bond or selected from O, C=O, SO2, CR4R4,

[0218]

[0219] In certain embodiments, the REand RF, together with the atoms to which they are

[0220] attached, form

[0221]

[0222] . In further embodiments, the REand RF, together with the atoms to which

[0223] they are attached, form

[0224]

[0225] . In yet further embodiments, the REand RF, together

[0226] with the atoms to which they are attached, form

[0227]

[0228] . In still further

[0229] embodiments, the REand RF, together with the atoms to which they are attached, form

[0230]

[0231] .

[0232] In certain embodiments, the REand RF, together with the atoms to which they are

[0233] attached, form

[0234]

[0235] In certain embodiments, the at least one unit of Formula lb is a unit of Formula Ic:

[0236]

[0237] In further embodiments, the at least one unit of Formula Ic is:

[0238]

[0239] In yet further embodiments, the at least one unit of formula Ic is:

[0240]

[0241] In still further embodiments, the at least one unit of formula Ic is:

[0242]

[0243] In certain embodiments, the at least one unit of formula Ic is:

[0244]

[0245] In further embodiments, the at least one unit of formula Ic is:

[0246]

[0247] In certain embodiments, the composite membranes comprise a plurality of polymer chains comprising at least one unit of Formula V:

[0248]

[0249] (V);

[0250] wherein:

[0251] R1and R2are independently selected from hydride group, alkyl groups, aryl groups, heterocyclic groups, halogen groups, groups including a — O — moiety, groups including a — O(CO) — moiety, groups including a — O(CO)O — moiety, groups including a O(CO)N< moiety, groups including a — S — moiety, groups including a — B< moiety, — NO2, groups including a — N< moiety, groups including a — P< moiety, groups including a — (PO)< moiety, — CHO, groups including a — (CO) — moiety, groups including a — (CO)O — moiety, and groups including a — (CO)N< moiety;

[0252] wherein X1and X2are independently selected from — [O] —, — [S] —, — [B(O)Ra] —, — [NRa]—, — [P(O)Ra]—, — [(PO)(O)Ra]—, —[CO]—, — [CRaRb]—, — [C(O)Ra(O)Rb]—, and — [Si(O)Ra(O)Rb]—, and Raand Rbare independently selected from hydride group, alkyl groups, aryl groups, and heterocyclic groups; and

[0253] wherein M is selected from aromatic groups and heterocyclic groups.

[0254] In further embodiments, the composite membranes comprise a plurality of polymer chains comprising at least one unit of Formula Va:

[0255]

[0256] (Va); wherein:

[0257] each R3is, independently at each occurrence, selected from C1-C4 alkyl, C1-C4 fluoroalkyl, halo, optionally substituted amino, and hydroxy;

[0258] each R4and R5is, independently at each occurrence, selected from H, C1-C4 alkyl, C1-C4 fluoroalkyl, halo, optionally substituted amino, and hydroxy;

[0259] each o is, independently at each occurrence, 0, 1, 2, or 3;

[0260] C is, independently at each occurrence, selected from:

[0261]

[0262] represents a point of attachment to the unit of Formula Va; and

[0263] D is, independently at each occurrence, a bond or selected from O, C=O, SO2, CR4R4,

[0264]

[0265] In further embodiments, the composite membranes comprise a plurality of polymer chains, which comprise at least one unit of Formula Vb:

[0266]

[0267] In yet further embodiments, the composite membranes comprise a plurality of polymer chains, which comprise at least one unit selected from:

[0268]

[0269] Suitable methods of preparing polymers having a structure according to any one of Formulae V-Vb, as described above, may be found in,.e.g., Abdulhamid, et al. Chem. Mater.

[0270] 2019, 31, 1767-1774; the entire contents of which are incorporated by reference herein.

[0271] In certain embodiments, the gutter layer is present. In further embodiments, the gutter layer comprises polysiloxane. In yet further embodiments, the thickness of the gutter layer is from 0.01 microns to about 10 microns. In still further embodiments, the thickness of the gutter layer is about 0.01 microns. In certain embodiments, the thickness of the gutter layer is about 0.1 microns. In further embodiments, the thickness of the gutter layer is about 1 micron. In yet further embodiments, the thickness of the gutter layer is about 2 microns. In still further embodiments, the thickness of the gutter layer is about 3 microns. In certain embodiments, the thickness of the gutter layer is about 4 microns. In further embodiments, the thickness of the gutter layer is about 5 microns. In yet further embodiments, the thickness of the gutter layer is about 6 microns. In still further embodiments, the thickness of the gutter layer is about 7 microns. In certain embodiments, the thickness of the gutter layer is about 8 microns. In further embodiments, the thickness of the gutter layer is about 9 microns. In yet further embodiments, the thickness of the gutter layer is about 10 microns. In still further embodiments, the gutter layer is absent.

[0272] In certain embodiments, the hollow fiber has an outer diameter of from about

[0273] 200 microns to about 800 microns. In further embodiments, the hollow fiber has an outer diameter of about 200 microns. In yet further embodiments, the hollow fiber has an outer diameter of about 300 microns. In still further embodiments, the hollow fiber has an outer diameter of about 400 microns. In yet further embodiments, the hollow fiber has an outer diameter of about 500 microns. In still further embodiments, the hollow fiber has an outer diameter of about 600 microns. In yet further embodiments, the hollow fiber has an outer diameter of about 700 microns. In yet further embodiments, the hollow fiber has an outer diameter of about 800 microns.

[0274] In further embodiments, the hollow fiber has an inner diameter from about 50 microns to about 400 microns, provided the inner diameter is less than the outer diameter. In further embodiments, the hollow fiber has an inner diameter of about 50 microns. In yet further embodiments, the hollow fiber has an inner diameter of about 100 microns. In still further embodiments, the hollow fiber has an inner diameter of about 150 microns. In yet further embodiments, the hollow fiber has an inner diameter of about 200 microns. In still further embodiments, the hollow fiber has an inner diameter of about 250 microns. In yet further embodiments, the hollow fiber has an inner diameter of about 300 microns. In still further embodiments, the hollow fiber has an inner diameter of about 350 microns. In still further embodiments, the hollow fiber has an inner diameter of about 400 microns. Provided the inner diameter is less than the outer diameter.

[0275] In certain embodiments, the hollow fiber has a fiber length of about 100 meters or less. In further embodiments, the hollow fiber has a fiber length of about 90 meters or less. In yet further embodiments, the hollow fiber has a fiber length of about 80 meters or less. In still embodiments, the hollow fiber has a fiber length of about 70 meters or less. In yet further embodiments, the hollow fiber has a fiber length of about 60 meters or less. In still further embodiments, the hollow fiber has a fiber length of about 50 meters or less. In yet further embodiments, the hollow fiber has a fiber length of about 40 meters or less. In still further embodiments, the hollow fiber has a fiber length of about 30 meters or less. In yet further embodiments, the hollow fiber has a fiber length of about 20 meters or less. In still further embodiments, the hollow fiber has a fiber length of about 10 meters or less. In yet further embodiments, the hollow fiber has a fiber length of about 5 meters or less. In still further embodiments, the hollow fiber has a fiber length of about 1 meter or less.

[0276] In certain embodiments, the composite membranes disclosed herein further comprise: a sealing layer comprising a permeable elastic polymer, said sealing layer having a first side, a second side, and a thickness;

[0277] wherein the second side of the selective layer is disposed along the first side of the sealing layer.

[0278] In certain embodiments, the thickness of the sealing layer is from 0.01 microns to about 10 microns. In further embodiments, the thickness of the sealing layer is about 0.01 microns. In yet further embodiments, the thickness of the sealing layer is about 0.1 microns. In still further embodiments, the thickness of the sealing layer is about 1 micron. In certain embodiments, the thickness of the sealing layer is about 2 microns. In further embodiments, the thickness of the sealing layer is about 3 microns. In yet further embodiments, the thickness of the sealing layer is about 4 microns. In still further embodiments, the thickness of the sealing layer is about 5 microns. In certain embodiments, the thickness of the sealing layer is about 6 microns. In further embodiments, the thickness of the sealing layer is about 7 microns. In yet further embodiments, the thickness of the sealing layer is about 8 microns. In still further embodiments, the thickness of the sealing layer is about 9 microns. In certain embodiments, the thickness of the sealing layer is about 10 microns. In further embodiments, the sealing layer comprises polysiloxane.

[0279] In certain embodiments, the composite membranes disclosed herein further comprise: a non-woven layer comprising a polymeric material, said non-woven layer having a first side, a second side, and a thickness;

[0280] wherein the second side of the non-woven layer is disposed along the first side of the support layer; and

[0281] the polymeric material is a polyolefin or polyester. In certain embodiments, the non-woven layer comprises at least one polyester; preferably wherein the polyester is PET. In further embodiments, the non-woven layer comprises at least one polyolefin. In yet further embodiments, the at least one polyolefin is selected from polyethylene, and polypropylene, or combinations thereof. In still further embodiments, the at least one polyolefin is a combination of polypropylene and polyethylene.

[0282] In certain embodiments, the thickness of the non-woven layer is from about 50 microns to about 300 microns. In further embodiments, the thickness of the non-woven layer is about 50 microns. In yet further embodiments, the thickness of the non-woven layer is about

[0283] 100 microns. In still further embodiments, the thickness of the non-woven layer is about

[0284] 150 microns. In certain embodiments, the thickness of the non-woven layer is about

[0285] 200 microns. In further embodiments, the thickness of the non-woven layer is about

[0286] 250 microns. In yet further embodiments, the thickness of the non-woven layer is about

[0287] 300 microns.

[0288] Hollow Fiber Membranes

[0289] In certain aspects, provided herein are hollow fiber membranes comprising: a selective layer comprising a plurality of polymer chains, said selective layer having an inner surface, an outer surface, and a thickness; wherein the plurality of polymer chains comprises at least one unit of Formula V:

[0290]

[0291] (V);

[0292] wherein:

[0293] R1and R2are independently selected from hydride group, alkyl groups, aryl groups, heterocyclic groups, halogen groups, groups including a — O — moiety, groups including a — O(CO) — moiety, groups including a — O(CO)O — moiety, groups including a O(CO)N< moiety, groups including a — S — moiety, groups including a — B< moiety, — NO2, groups including a — N< moiety, groups including a — P< moiety, groups including a — (PO)< moiety, — CHO, groups including a — (CO) — moiety, groups including a — (CO)O — moiety, and groups including a — (CO)N< moiety;

[0294] X1is selected from — [O]—, — [S]—, — [B(O)Ra]—,— [NRa]—, — [P(O)Ra]—, — [(PO)(O)Ra]—, —[CO]—, — [CRaRb]—, — [C(O)Ra(O)Rb]—, and— [Si(O)Ra(O)Rb]—, and Raand Rbare independently selected from hydride group, alkyl groups, aryl groups, and heterocyclic groups; and

[0295] M is selected from optionally substituted aromatic groups and heterocyclic groups. In certain embodiments, the plurality of polymer chains comprises at least one unit of Formula Va:

[0296]

[0297] (Va);

[0298] wherein:

[0299] each R3is, independently at each occurrence, selected from C1-C4 alkyl, C1-C4 fluoroalkyl, halo, optionally substituted amino, and hydroxy;

[0300] each R4and R5is, independently at each occurrence, selected from H, C1-C4 alkyl, C1-C4 fluoroalkyl, halo, optionally substituted amino, and hydroxy;

[0301] each o is, independently at each occurrence, 0, 1, 2, or 3;

[0302] C is, independently at each occurrence, selected from:

[0303]

[0304] ; wherein each * represents a point of attachment to the unit of Formula Va; and D is, independently at each occurrence, a bond or selected from O, C=O, SO2, CR4R4,

[0305] phenylene,

[0306]

[0307] In certain embodiments, the plurality of polymer chains comprises at least one unit of Formula Vb:

[0308]

[0309] wherein:

[0310] each R3is, independently at each occurrence, selected from C1-C4 alkyl, C1-C4 fluoroalkyl, halo, optionally substituted amino, and hydroxy;

[0311] each R4is, independently at each occurrence, selected from H, C1-C4 alkyl, C1-C4 fluoroalkyl, halo, optionally substituted amino, and hydroxy; and

[0312] each o is, independently at each occurrence, 0, 1, 2, or 3. In certain embodiments, the plurality of polymer chains comprises at least one unit of Formula lb:

[0313]

[0314] (lb);

[0315] wherein:

[0316] each R3is, independently at each occurrence, selected from C1-C4 alkyl, C1-C4 fluoroalkyl, halo, optionally substituted amino, and hydroxy;

[0317] each R4and R5is, independently at each occurrence, selected from H, C1-C4 alkyl, C1-C4 fluoroalkyl, halo, optionally substituted amino, and hydroxy;

[0318] A is, independently at each occurrence, selected from NRD, O, S, CRERF, S=O, and C=O; when present, B is, independently at each occurrence, selected from NRD, O, S, CRERF, and C=O;

[0319] wherein, when B is present, at least one of A and B is CRERFor C=O;

[0320] RDis, independently at each occurrence, selected from H, alkyl, -O-alkyl, or haloalkyl; REand RFare, independently at each occurrence, selected from H, OH, SH, halo, amine, alkyl, -C(=O)H, -O-alkyl, and haloalkyl,

[0321] or REand RF, together with the atom to which they are attached, form a cycloalkyl, cycloalkenyl, heterocycloalkyl or heterocycloalkenyl, which is optionally substituted with one or more RH, wherein RHis selected from H, alkyl, alkoxy, and hydroxy; optionally wherein REand RF, together with the atoms to which they are attached, form a

[0322] group selected from

[0323]

[0324] n is 0 or 1;

[0325] each o is, independently at each occurrence, 0, 1, 2, or 3;

[0326] — represents an optional bond;

[0327] C is, independently at each occurrence, selected from:

[0328]

[0329] ; wherein each * represents a point of attachment to the unit of Formula lb; and

[0330] D is, independently at each occurrence, a bond or selected from O, C=O, SO2, CR4R4,

[0331] phenylene,

[0332]

[0333] In certain embodiments, the plurality of polymer chains comprises at least one unit of Formula Ic:

[0334]

[0335] wherein:

[0336] A is, independently at each occurrence, selected from NRD, O, S, CRERF, S=O, and C=O; each R3is, independently at each occurrence, selected from C1-C4 alkyl, C1-C4 fluoroalkyl, halo, optionally substituted amino, and hydroxy;

[0337] each R4is, independently at each occurrence, selected from H, C1-C4 alkyl, C1-C4 fluoroalkyl, halo, optionally substituted amino, and hydroxy;

[0338] RDis, independently at each occurrence, selected from H, alkyl, -O-alkyl, or haloalkyl; REand RFare, independently at each occurrence, selected from H, OH, SH, halo, amine, alkyl, -C(=O)H, -O-alkyl, and haloalkyl

[0339] or REand RF, together with the atom to which they are attached, form a cycloalkyl, cycloalkenyl, heterocycloalkyl or heterocycloalkenyl, which is optionally substituted with one or more RH, wherein RHis selected from H, alkyl, alkoxy, and hydroxy;

[0340] optionally wherein REand RF, together with the atoms to which they are attached, form a

[0341] group selected from

[0342]

[0343] each o is, independently at each occurrence, 0, 1, 2, or 3.

[0344] In certain embodiments, the plurality of polymer chains comprises at least one unit of Formula Id:

[0345]

[0346] wherein: each R3is, independently at each occurrence, selected from C1-C4 alkyl, C1-C4 fluoroalkyl, halo, optionally substituted amino, and hydroxy; and

[0347] each o is, independently at each occurrence, 0, 1, 2, or 3.

[0348] In certain embodiments, the hollow fiber membrane further comprises: a sealing layer comprising a permeable elastic polymer; wherein sealing layer is disposed along the outer surface of the selective layer.

[0349] In certain embodiments, the thickness of the sealing layer is from 0.01 microns to about 10 microns. In further embodiments, the thickness of the sealing layer is about 0.01 microns. In yet further embodiments, the thickness of the sealing layer is about 0.1 microns. In still further embodiments, the thickness of the sealing layer is about 1 micron. In certain embodiments, the thickness of the sealing layer is about 2 microns. In further embodiments, the thickness of the sealing layer is about 3 microns. In yet further embodiments, the thickness of the sealing layer is about 4 microns. In still further embodiments, the thickness of the sealing layer is about

[0350] 5 microns. In certain embodiments, the thickness of the sealing layer is about 6 microns. In further embodiments, the thickness of the sealing layer is about 7 microns. In yet further embodiments, the thickness of the sealing layer is about 8 microns. In still further embodiments, the thickness of the sealing layer is about 9 microns. In certain embodiments, the thickness of the sealing layer is about 10 microns. In certain embodiments, the sealing layer comprises a norbornyl benzocyclobutene polymer, a polysiloxane, a fluorinated polymer, or a combination thereof. In certain embodiments, the hollow fiber membrane consists essentially of the selective layer.

[0351] In certain embodiments, the hollow fiber membrane has an outer diameter of from about 200 microns to about 800 microns. In further embodiments, the hollow fiber membrane has an outer diameter of about 200 microns. In yet further embodiments, the hollow fiber membrane has an outer diameter of about 300 microns. In still further embodiments, the hollow fiber membrane has an outer diameter of about 400 microns. In yet further embodiments, the hollow fiber membrane has an outer diameter of about 500 microns. In still further embodiments, the hollow fiber membrane has an outer diameter of about 600 microns. In yet further embodiments, the hollow fiber membrane has an outer diameter of about 700 microns. In yet further embodiments, the hollow fiber membrane has an outer diameter of about 800 microns. In further embodiments, the hollow fiber membrane has an inner diameter from about 50 microns to about 400 microns, provided the inner diameter is less than the outer diameter. In further embodiments, the hollow fiber membrane has an inner diameter of about 50 microns. In yet further embodiments, the hollow fiber membrane has an inner diameter of about

[0352] 100 microns. In still further embodiments, the hollow fiber membrane has an inner diameter of about 150 microns. In yet further embodiments, the hollow fiber membrane has an inner diameter of about 200 microns. In still further embodiments, the hollow fiber membrane has an inner diameter of about 250 microns. In yet further embodiments, the hollow fiber membrane has an inner diameter of about 300 microns. In still further embodiments, the hollow fiber membrane has an inner diameter of about 350 microns. In still further embodiments, the hollow fiber membrane has an inner diameter of about 400 microns. Provided the inner diameter is less than the outer diameter.

[0353] In certain embodiments, the hollow fiber membrane has a fiber length of about

[0354] 100 meters or less. In further embodiments, the hollow fiber membrane has a fiber length of about 90 meters or less. In yet further embodiments, the hollow fiber membrane has a fiber length of about 80 meters or less. In still embodiments, the hollow fiber membrane has a fiber length of about 70 meters or less. In yet further embodiments, the hollow fiber membrane has a fiber length of about 60 meters or less. In still further embodiments, the hollow fiber membrane has a fiber length of about 50 meters or less. In yet further embodiments, the hollow fiber membrane has a fiber length of about 40 meters or less. In still further embodiments, the hollow fiber membrane has a fiber length of about 30 meters or less. In yet further embodiments, the hollow fiber membrane has a fiber length of about 20 meters or less. In still further embodiments, the hollow fiber membrane has a fiber length of about 10 meters or less. In yet further embodiments, the hollow fiber membrane has a fiber length of about 5 meters or less. In still further embodiments, the hollow fiber membrane has a fiber length of about 1 meter or less.

[0355] In certain embodiments, the hollow fiber membrane is selective for separating CH₄ from He. In certain embodiments, the hollow fiber membrane is selective for separating H₂ from N₂. Gas Permeance

[0356] The composite membranes or hollow fiber membrane of the present disclosure exhibit gas permeance values for particular gases which may be expressed in the unit GPU, which is defined as: 1 GPU = 10-6cm3(STP) / (cm2s cm Hg). In certain embodiments, the composite membrane or hollow fiber membrane has a gas permeance for He (PHe) from about 1 to about 2000 GPU. In some embodiments, the composite membrane or hollow fiber membrane has a gas permeance for He (PHe) from about 0.1 GPU to about 5 GPU. In certain embodiments, the composite membrane or hollow fiber membrane has a gas permeance for He (PHe) from about 6 GPU to about 10 GPU. In some embodiments, the composite membrane or hollow fiber membrane has a gas permeance for He (PHe) from about 11 GPU to about 75 GPU. In certain embodiments, the composite membrane or hollow fiber membrane has a gas permeance for He (PHe) from about 76 GPU to about 200 GPU. In some embodiments, the composite membrane or hollow fiber membrane has a gas permeance for He (PHe) from about 201 GPU to about 600 GPU. In certain embodiments, the composite membrane or hollow fiber membrane has a gas permeance for He (PHe) greater than about 200 GPU. In further embodiments, the composite membrane or hollow fiber membrane has a gas permeance for He (PHe) of about 1 GPU. In yet further embodiments, the composite membrane or hollow fiber membrane has a gas permeance for He (PHe) of about 250 GPU. In still further embodiments, the composite membrane or hollow fiber membrane has a gas permeance for He (PHe) of about 500 GPU. In certain embodiments, the composite membrane or hollow fiber membrane has a gas permeance for He (PHe) of about 750 GPU. In further embodiments, the composite membrane or hollow fiber membrane has a gas permeance for He (PHe) of about 1000 GPU. In yet further embodiments, the composite membrane or hollow fiber membrane has a gas permeance for He (PHe) of about 1250 GPU. In still further embodiments, the composite membrane or hollow fiber membrane has a gas permeance for He (PHe) of about 1500 GPU. In certain embodiments, the composite membrane or hollow fiber membrane has a gas permeance for He (PHe) of about 1750 GPU. In further embodiments, the composite membrane or hollow fiber membrane has a gas permeance for He (PHe) of about 2000 GPU.

[0357] In certain embodiments, the composite membrane or hollow fiber membrane has a gas permeance for H2(PH2) from about 1 to about 2000 GPU. In some embodiments, the membrane has a gas permeance for H2(PH2) from about 0.1 GPU to about 5 GPU. In certain embodiments, the membrane has a gas permeance for H2(PH2) from about 6 GPU to about 10 GPU. In some embodiments, the membrane has a gas permeance for H2(PH2) from about 11 GPU to about 75 GPU. In certain embodiments, the membrane has a gas permeance for H2(PH2) from about 76 GPU to about 200 GPU. In some embodiments, the membrane has a gas permeance for H2(PH2) from about 201 GPU to about 600 GPU. In certain embodiments, the membrane has a gas permeance for H2(PH2) greater than about 200 GPU. In further embodiments, the composite membrane or hollow fiber membrane has a gas permeance for H2(PH2) of about 1 GPU. In yet further embodiments, the composite membrane or hollow fiber membrane has a gas permeance for H2(PH2) of about 250 GPU. In still further embodiments, the composite membrane or hollow fiber membrane has a gas permeance for H2(PH2) of about 500 GPU. In certain embodiments, the composite membrane or hollow fiber membrane has a gas permeance for H2(PH2) of about 750 GPU. In further embodiments, the composite membrane or hollow fiber membrane has a gas permeance for H2(PH2) of about 1000 GPU. In yet further embodiments, the composite membrane or hollow fiber membrane has a gas permeance for H2(PH2) of about 1250 GPU. In still further embodiments, the composite membrane or hollow fiber membrane has a gas permeance for H2(PH2) of about 1500 GPU. In certain embodiments, the composite membrane or hollow fiber membrane has a gas permeance for H2(PH2) of about 1750 GPU. In further embodiments, the composite membrane or hollow fiber membrane has a gas permeance for H2(PH2) of about 2000 GPU.

[0358] In certain embodiments, the composite membrane or hollow fiber membrane is selective for separating CH4from He. In some embodiments, the selectivity of the composite membrane or hollow fiber membrane (PHe / PCH4) is from about 100 to about 600. In some embodiments, the selectivity of the composite membrane or hollow fiber membrane (PHe / PCH4) is from about 0 to about 50. In certain embodiments, the selectivity of the composite membrane or hollow fiber membrane (PHe / PCH4) is from about 51 to about 150. In some embodiments, the selectivity of the composite membrane or hollow fiber membrane (PHe / PCH4) is from about 151 to about 300. In certain embodiments, the selectivity of the composite membrane or hollow fiber membrane (PHe / PCH4) is from about 301 to about 450. In some embodiments, the selectivity of the composite membrane or hollow fiber membrane (PHe / PCH4) is from about 451 to about 3500. In certain embodiments, the selectivity of the composite membrane or hollow fiber membrane (PHe / PCH4) is greater than about 450. In some embodiments, the selectivity of the composite membrane or hollow fiber membrane (PHe / PCH4) is from about 0 to about 10. In certain embodiments, the selectivity of the composite membrane or hollow fiber membrane (PHe / PCH4) is from about 11 to about 50. In some embodiments, the selectivity of the composite membrane or hollow fiber membrane (PHe / PCH4) is from about 51 to about 150. In certain embodiments, the selectivity of the composite membrane or hollow fiber membrane (PHe / PCH4) is greater than about 150. In some embodiments, the selectivity of the composite membrane or hollow fiber membrane (PHe / PCH4) is from about 150 to about 3500. In certain embodiments, the selectivity of the composite membrane or hollow fiber membrane (PHe / PCH4) is from about 100 to about 500. In further embodiments, the selectivity of the composite membrane or hollow fiber membrane (PHe / PCH4) is from about 100 to about 400. In yet further embodiments, the selectivity of the composite membrane or hollow fiber membrane (PHe / PCH4) is from about 200 to about 300. In still further embodiments, the selectivity of the composite membrane or hollow fiber membrane (PHe / PCH4) is selected from about 200, about 225, about 250, about 275, about 300, about 325, about 350, about 375, about 400, about 425, about 450, about 475, and about 500.

[0359] In certain embodiments, the composite membrane or hollow fiber membrane is selective for separating H2from N2. In some embodiments, the selectivity of the composite membrane or hollow fiber membrane (PH2 / PN2) is from about 0 to about 50. In certain embodiments, the selectivity of the composite membrane or hollow fiber membrane (PH2 / PN2) is from about 51 to about 150. In some embodiments, the selectivity of the composite membrane or hollow fiber membrane (PH2 / PN2) is from about 151 to about 300. In certain embodiments, the selectivity of the composite membrane or hollow fiber membrane (PH2 / PN2) is from about 301 to about 450. In some embodiments, the selectivity of the composite membrane or hollow fiber membrane (PH2 / PN2) is from about 451 to about 3500. In certain embodiments, the selectivity of the composite membrane or hollow fiber membrane (PH2 / PN2) is greater than about 450. In some embodiments, the selectivity of the composite membrane or hollow fiber membrane (PH2 / PN2) is from about 0 to about 10. In certain embodiments, the selectivity of the composite membrane or hollow fiber membrane (PH2 / PN2) is from about 11 to about 50. In some embodiments, the selectivity of the composite membrane or hollow fiber membrane (PH2 / PN2) is from about 51 to about 150. In certain embodiments, the selectivity of the composite membrane or hollow fiber membrane (PH2 / PN2) is greater than about 150. In some embodiments, the selectivity of the composite membrane or hollow fiber membrane (PH2 / PN2) is from about 150 to about 3500. In further embodiments, the selectivity of the composite membrane or hollow fiber membrane (PH2 / PN2) is from about 100 to about 300. In yet further embodiments, the selectivity of the composite membrane or hollow fiber membrane (PH2 / PN2) is from about 150 to about 200. In still further embodiments, the selectivity of the composite membrane or hollow fiber membrane (PH2 / PN2) is selected from about 150, about 175, about 200, about 225, about 250, about 275, and about 300.

[0360] The composite membranes or hollow fiber membranes of the present disclosure exhibit selectivity for gas separation without the need for long-term curing. In certain embodiments, the composite material or hollow fiber membrane exhibits said selectivity without being cured for more than about 100 days. In further embodiments, the composite material or hollow fiber membrane exhibits said selectivity without being cured for more than about 7 days. In yet further embodiments, the composite material or hollow fiber membrane exhibits said selectivity without being cured.

[0361] Methods of Making Membranes

[0362] In certain aspects, provided herein are methods of preparing a composite membrane of the present disclosure. In certain embodiments, the method comprises:

[0363] providing a mesoporous support in the form of a hollow fiber; and

[0364] coating the hollow fiber with the selective solution, thereby forming the hollow fiber composite membrane.

[0365] In further aspects, provided herein are methods of preparing a composite membrane of the present disclosure. In certain embodiments, the method comprises:

[0366] providing a support mixture comprising a support polymer precursor, a first solvent, and a second solvent, the support mixture having a first solvent: second solvent ratio;

[0367] contacting the support mixture with a substrate, thereby forming a nascent support; degassing the nascent support, the thereby forming a mesoporous support;

[0368] spinning the mesoporous support into a hollow fiber; washing and cross-linking the hollow fiber;

[0369] coating the hollow fiber with the selective solution, thereby forming the hollow fiber composite membrane.

[0370] In certain aspects, provided herein are methods of preparing a hollow fiber membrane of the present disclosure.

[0371] Methods of Separating Fluids

[0372] In yet further aspects, provided herein are methods for separating a mixture of fluids comprising a first fluid and a second fluid, the methods comprising:

[0373] contacting a fluid mixture with a composite membrane or a hollow fiber membrane of the present disclosure, thereby separating the mixture of fluids into:

[0374] a permeate comprising a first portion of the first fluid and a first portion of the second fluid; and

[0375] a retentate comprising a second portion of the second fluid.

[0376] As will be appreciated, the efficiency and selectivity of such separations will be affected by any number of process parameters, including the initial composition of the mixture of fluids, pressures, temperatures, etc. Additionally, as will be apparent to one of skill in the art, when describing percentages that are greater than or less than (or higher or lower than) other percentages, this describes an additive or subtractive change in the total percentage. For instance, for a mixture of fluids comprising 50% of the first fluid and 50% of the second fluid, where the percentage of the first fluid is said to increase by 5%, this would result in a mixture comprising 55% first fluid.

[0377] In certain embodiments, the volume percent of the first fluid in the permeate is higher than the volume percent of the first fluid in the mixture of fluids by about 1% to about 99%. In further embodiments, the volume percent of the first fluid in the permeate is higher than the volume percent of the first fluid in the mixture of fluids by at least about 1%, about 5%, about 10%, about 20%, about 30%, about 40%, about 50%, about 60%, about 70%, about 80%, about 90%, about 95%, about 97.5%, or about 99%. In yet further embodiments, the volume percent of the first fluid in the permeate is higher than the volume percent of the first fluid in the mixture of fluids by at most about 1%, about 5%, about 10%, about 20%, about 30%, about 40%, about 50%, about 60%, about 70%, about 80%, about 90%, about 95%, about 97.5%, or about 99%. In yet further embodiments, the volume percent of the first fluid in the permeate is higher than the volume percent of the first fluid in the mixture of fluids by about 1%, about 5%, about 10%, about 20%, about 30%, about 40%, about 50%, about 60%, about 70%, about 80%, about 90%, about 95%, about 97.5%, or about 99%. In some embodiments, the first fluid is He. In some embodiments, the first fluid is combined He and H2.

[0378] In certain embodiments, the volume percent of the first fluid in the permeate is from about 99% to about 1%. In further embodiments, the volume percent of the first fluid in the permeate is greater than about 99%, about 95%, about 90%, about 80%, about 70%, about 60%, about 50%, about 40%, about 30%, about 20%, about 10%, about 5%, about 2.5%, and about 1%; preferably wherein volume percent of the first fluid in the permeate is greater than about 95%. In yet further embodiments, the volume percent of the first fluid in the permeate is less than about 99%, about 95%, about 90%, about 80%, about 70%, about 60%, about 50%, about 40%, about 30%, about 20%, about 10%, about 5%, about 2.5%, and about 1%; preferably wherein volume percent of the first fluid in the permeate is less than about 95%. In still further embodiments, the volume percent of the first fluid in the permeate is about 99%, about 95%, about 90%, about 80%, about 70%, about 60%, about 50%, about 40%, about 30%, about 20%, about 10%, about 5%, about 2.5%, and about 1%; preferably wherein volume percent of the first fluid in the permeate is about 95%. In some embodiments, the first fluid is He. In some embodiments, the first fluid is combined He and H2.

[0379] In certain embodiments, the volume of the first fluid in the permeate is higher than about 10% to about 99% by volume of the first fluid in the mixture of fluids. In further embodiments, the volume of the first fluid in the permeate is higher than about 10% by volume, about 20% by volume, about 30% by volume, about 40% by volume, about 50% by volume, about 60% by volume, about 70% by volume, about 80% by volume, about 90% by volume, about 95% by volume, about 98% by volume, or about 99% by volume of the volume of the first fluid in the mixture of fluids; preferably wherein the volume of the first fluid in the permeate is higher than about 80% of the volume of the first fluid in the mixture of fluids. In yet further embodiments, the volume of the first fluid in the permeate is lower than about 10% by volume, about 20% by volume, about 30% by volume, about 40% by volume, about 50% by volume, about 60% by volume, about 70% by volume, about 80% by volume, about 90% by volume, about 95% by volume, about 98% by volume, or about 99% by volume of the volume of the first fluid in the mixture of fluids; preferably wherein the volume of the first fluid in the permeate is lower than about 80% of the volume of the first fluid in the mixture of fluids. In still further embodiments, the volume of the first fluid in the permeate is about 10% by volume, about 20% by volume, about 30% by volume, about 40% by volume, about 50% by volume, about 60% by volume, about 70% by volume, about 80% by volume, about 90% by volume, about 95% by volume, about 98% by volume, or about 99% by volume of the volume of the first fluid in the mixture of fluids; preferably wherein the volume of the first fluid in the permeate is about 80% of the volume of the first fluid in the mixture of fluids. In some embodiments, the first fluid is He. In some embodiments, the first fluid is combined He and H2.

[0380] In certain embodiments, the first fluid is He, and the second fluid is CH4. In further embodiments, the first fluid is H2, and the second fluid is N2. In certain embodiments, the first fluid is He, and the second fluid is N2. In certain embodiments, the first fluid is He and H2, and the second fluid is N2.

[0381] In certain embodiments, the pores of the support member are substantially parallel to the direction of fluid flow through the composite membrane (i.e., direct flow separation). In further embodiments, the pores of the support member are substantially perpendicular to the direction of fluid flow through the composite membrane (i.e., tangential flow separation).

[0382] In certain embodiments, provided herein are methods of separating a mixture of fluids, wherein the fluid mixture is contacted with a hollow fiber membrane of the present disclosure; and the direction of fluid flow through the hollow fiber membrane is through the thickness of the selective layer (i.e., direct flow separation). In further embodiments, the fluid mixture is contacted with a hollow fiber membrane of the present disclosure; and the direction of fluid flow through the hollow fiber membrane is along the inner surface or along the outer surface of the selective layer (i.e., tangential flow separation).

[0383]

[0384] In certain aspects, provided herein are copolymers comprising: at least one first unit comprising:

[0385] a subunit of Formula I*:

[0386]

[0387] (I*); and

[0388] a subunit of any one of Formula II*, III*, IV-a*, or IV-b*:

[0389]

[0390] (IV-b*) and at least one second unit comprising:

[0391] a subunit of Formula I*:

[0392]

[0393] (I*); and

[0394] a subunit of any one of Formula V* and VI*:

[0395]

[0396] (VI*);

[0397] wherein:

[0398] A is, independently at each occurrence, selected from:

[0399]

[0400]

[0401]

[0402] wherein each * represents a point of attachment to the unit of Formula I*; and

[0403] FAis, independently at each occurrence, selected from a bond, O, S, C=O, SO2,

[0404]

[0405] V

[0406] **L J **

[0407] u0, wherein each ** represents a point of attachment to the adjacent phenylene rings of A;

[0408] each RAand RBis, independently at each occurrence, selected from H, halo, hydroxyl, C1-C4 alkyl, C1-C4 haloalkyl, and aryl; wherein each is optionally substituted;

[0409] wherein one instance of cwv* of Formula I* in the first unit represents a connection point to any one of Formula II*, III*, IV-a* or IV-b* and the other ' / vvv' of Formula I* represents a connection point to the rest of the polymer; wherein one instance of

[0410]

[0411] of Formula I* in the second unit represents a connection point to any one of Formula V* or VI*, and the other ' / vw' of Formula I* represents a connection point to the rest of the polymer; B is, independently at each occurrence, -[(CH2)2O]p-[O(CH2)2]q-[O(CH2)2]r-, - [(CH2)3O]p-[O(CH2)3]q-[(CH2)3O]r-, -[(CH2)]pCH(COOH)-, -Si(CH3)2- [OSi(CH3)2]r, or -OSi(CH3)2[(CH2)]q-; wherein:

[0412] each p is, independently at each occurrence, an integer from 0 to about 10; each q is, independently at each occurrence, an integer from 0 to about 10; and each r is, independently at each occurrence, an integer from 0 to about 10; each R1is, independently at each occurrence, selected from halo, hydroxyl, alkyl, haloalkyl, acetyl, acetoxy, acyloxy, and carboxyl; wherein each is optionally substituted;

[0413] each m is, independently at each occurrence, 0, 1, 2, 3, or 4;

[0414] CAis, independently at each occurrence, selected from a bond, O, C=O, NHC(=O),

[0415]

[0416] CBis, independently at each occurrence, selected from

[0417]

[0418]

[0419] wherein each * represents a point of attachment to adjacent phenylene rings of IV-b*;

[0420] each Rcis, independently at each occurrence, selected from H, halo, hydroxyl, C1-C4 alkyl, C1-C4 haloalkyl, and aryl, wherein each is optionally substituted;

[0421] wherein one instance of ' / w' inFormula II*, III*, IV-a* or IV-b* in the first unit represents a connection point to Formula I* and the other instance of ' / vw' in Formula II*, III*, IV- a* or IV-b* represents a connection point to the rest of the polymer;

[0422] D is, independently at each occurrence, selected from NRD, O, S, CRERF, SO, and C=O; when present, E is, independently at each occurrence, selected from NRD, O, S, CRERF, and C=O;

[0423] wherein, when E is present, at least one of D and E is CRERFor C=O;

[0424] RDis, independently at each occurrence, selected from H, alkyl, -O-alkyl, or haloalkyl;

[0425] REand RFare, independently at each occurrence, selected from H, OH, SH, halo, amine, alkyl, -C(=0)H, -O-alkyl, and haloalkyl;

[0426] or REand RF, together with the atom to which they are attached, form a cycloalkyl, cycloalkenyl, heterocycloalkenyl, or heterocycloalkyl, which is optionally substituted with one or more RH, wherein RHis selected from H, alkyl, alkoxy, and hydroxy; optionally wherein REand RF, together with the atoms to which they are attached,

[0427] form a group selected from

[0428]

[0429]

[0430] n is 0 or 1;

[0431] — represents an optional bond;

[0432] R2is, independently at each occurrence, selected from halo, C1-C4 alkyl, C1-C4 haloalkyl, C1-C4 haloalkoxyl, carboxyl, optionally substituted amino, and hydroxy; each o is, independently at each occurrence, 0, 1, 2, or 3; and

[0433] wherein one instance of cwv* in Formula V* or VI* represents a connection point to Formula I* and the other instance of ' / vv\ inFormula V* or VI* represents a connection point to the rest of the polymer.

[0434] As will be appreciated, any suitable dianhydride may be used to prepare the subunit of Formula I*. In certain embodiments, the subunit of Formula I* is derived from a dianhydride selected from Table 1:

[0435] Table 1. Dianhydrides for Formula I*

[0436]

[0437]

[0438] As will be appreciated, any suitable commercially available diamine can be used to prepare the subunit of Formula III*. In certain embodiments, the subunit of Formula III* is derived from a diamine selected from Table 2:

[0439] Table 2. Diamines for Formula III*

[0440]

[0441] or a combination thereof. In further embodiments, the copolymer comprises a first subunit of Formula III*, and a second subunit of Formula III*, wherein the first subunit of Formula III* is derived from a first diamine precursor, and the second subunit of Formula III* is derived from a second subunit precursor, and the first diamine precursor is different than the second subunit precursor. In certain embodiments, A is, independently at each occurrence, selected from:

[0442]

[0443] Formula I*; and

[0444] FAis, independently at each occurrence, selected from a bond, O, S, C=O, SO2, NRA

[0445]

[0446] FBis, independently at each occurrence, selected from

[0447]

[0448] wherein each ** represents a point of attachment to adjacent phenyl rings of A; and

[0449] RAis, independently at each occurrence, selected from H, C1-C4 alkyl, C1-C4 fluoroalkyl, and aryl.

[0450] In certain embodiments, the subunit of Formula I* is selected from:

[0451]

[0452]

[0453] In some embodiments, the at least one first unit comprises the subunit of Formula I* and the subunit of Formula II*. In further embodiments, B is, independently at each occurrence, -CH2CH(COOH)- or -Si(CH3)2-[OSi(CH3)2]rOSi(CH3)2(CH2)3-. In yet further embodiments, the

[0454] subunit of Formula II* is selected from

[0455]

[0456] and

[0457]

[0458] In certain embodiments, the at least one first unit comprises: the subunit of Formula I* and the subunit of Formula III*. In further embodiments, the subunit of Formula III* is selected from:

[0459]

[0460] In some embodiments, each R1is, independently at each occurrence, selected from halo, hydroxyl, C1-C4 alkyl, C1-C4 fluoroalkyl, acetyl, acyloxy, and carboxyl; wherein each is optionally substituted with amino, hydroxy, or amino and hydroxy. In further embodiments, each R1is, independently at each occurrence, selected from halo, hydroxyl, unsubstituted C1-C4 alkyl, unsubstituted C1-C4 fluoroalkyl, unsubstituted acetyl, unsubstituted acyloxy, and unsubstituted carboxyl. In yet further embodiments, each R1is, independently at each occurrence, selected from halo, hydroxyl, substituted C1-C4 alkyl, substituted C1-C4 fluoroalkyl, substituted acetyl, substituted acyloxy, and substituted carboxyl; wherein each instance of a substituted R1is substituted with amino, hydroxy, or amino and hydroxy. In certain preferred embodiments, at least one R1is fluoroalkyl (e.g., C1-C4 fluoroalkyl). In further preferred embodiments, at least one R1is fluoroalkyl (e.g., C1-C4 fluoroalkyl).

[0461] In certain embodiments, the at least one first unit comprises: the subunit of Formula I* and the subunit of Formula IV-a* or IV-b*. In further embodiments, the at least one first unit comprises: the subunit of Formula I* and the subunit of Formula IV-a*. In yet further

[0462] embodiments, the subunit of Formula IV-a* is selected from:

[0463]

[0464]

[0465] In certain embodiments, the at least one first unit comprises: the subunit of Formula I* and the subunit of Formula IV-b*. In further embodiments, the subunit of Formula IV-b* is

[0466] selected from:

[0467]

[0468]

[0469] In some embodiments, the at least one second unit comprises: the subunit of Formula I* and the subunit of Formula V*. In further embodiments, the subunit of Formula V* is selected

[0470]

[0471]

[0472] In certain embodiments, the at least one second unit comprises: the subunit of Formula I* and the subunit of Formula VI*. In further embodiments, the subunit of Formula VI* is selected

[0473]

[0474] In some embodiments, the first unit has the structure of Formula la*, lb*, or Ic*:

[0475]

[0476] (la*);

[0477]

[0478] (Ic*).

[0479] 5 In further embodiments, the first unit has the structure of Formula la-1*, Ib-l* or Ic-l*:

[0480]

[0481] (Ib-1*); or

[0482]

[0483] (Ic-1*).

[0484] In yet further embodiments, RAis fluoroalkyl. In other embodiments, RAis CF3. In some embodiments, the second unit has the structure of Formula IIa* or IIb*:

[0485]

[0486] (IIb*). In further embodiments, the second unit has the structure of Formula IIa-1* or IIb-1*:

[0487]

[0488] (IIb-1*).

[0489] In yet further embodiments, RAis fluoroalkyl. In other embodiments, RAis CF3.

[0490] Composite Membranes

[0491] In certain aspects, provided herein are composite membranes comprising:

[0492] a porous membrane support layer comprising a plurality of pores extending through the support layer, said support layer having a first side, a second side, and a thickness; and optionally, a gutter layer comprising a permeable polymer, said gutter layer having a first side, a second side, and a thickness;

[0493] a thin film membrane selective layer comprising a plurality of polymer chains, said selective layer having a first side, a second side, and a thickness;

[0494] wherein:

[0495] when the gutter layer is present, the second side of the support layer is disposed along the first side of the gutter layer, and the second side of the gutter layer is disposed along the first side of the selective layer; when the gutter layer is absent, the second side of the support layer is disposed along the first side of the selective layer; and

[0496] the thickness of the selective layer is less than about 10 microns.

[0497] In some embodiments, the composite membrane is in the form of a hollow fiber.

[0498] In certain embodiments, the thickness of the selective layer of the hollow fiber composite membrane is from about 0.01 to about 10 microns. In further embodiments, the thickness of the selective layer is from about 0.05 to about 5 microns. In yet further embodiments, the thickness of the selective layer is from about 0.1 to about 1.5 microns. In still further embodiments, the thickness of the selective layer is selected from about, 0.01 microns, about 0.05 microns, about 0.1 microns, about 0.25 microns, about 0.5 microns, about 0.75 microns, and about 1 micron; preferably wherein the thickness of the selective layer is about 0.01 micron.

[0499] In certain embodiments, the thickness of the selective layer is about 0.05 microns. In certain embodiments, the thickness of the selective layer is about 0.1 microns. In further embodiments, the thickness of the selective layer is about 0.2 microns. In yet further embodiments, the thickness of the selective layer is about 0.3 microns. In still further embodiments, the thickness of the selective layer is about 0.4 microns. In certain embodiments, the thickness of the selective layer is about 0.5 microns. In further embodiments, the thickness of the selective layer is about 0.6 microns. In yet further embodiments, the thickness of the selective layer is about 0.7 microns. In still further embodiments, the thickness of the selective layer is about 0.8 microns. In certain embodiments, the thickness of the selective layer is about

[0500] 0.9 microns.

[0501] In certain embodiments, the thickness of the selective layer is about 1 micron. In further embodiments, the thickness of the selective layer is about 2 microns. In yet further embodiments, the thickness of the selective layer is about 3 microns. In still further embodiments, the thickness of the selective layer is about 4 microns. In certain embodiments, the thickness of the selective layer is about 5 microns. In further embodiments, the thickness of the selective layer is about 6 microns. In yet further embodiments, the thickness of the selective layer is about 7 microns. In still further embodiments, the thickness of the selective layer is about 8 microns. In certain embodiments, the thickness of the selective layer is about 9 microns. In further embodiments, the thickness of the selective layer is about 10 microns. In certain embodiments, the thickness of the selective layer is less than about 10 microns. In further embodiments, the thickness of the selective layer is less than about 9 microns. In yet further embodiments, the thickness of the selective layer is less than about 8 microns. In still further embodiments, the thickness of the selective layer is less than about 7 microns. In certain embodiments, the thickness of the selective layer is less than about 6 microns. In further embodiments, the thickness of the selective layer is less than about 5 microns. In yet further embodiments, the thickness of the selective layer is less than about 4 microns. In still further embodiments, the thickness of the selective layer is less than about 3 microns. In certain embodiments, the thickness of the selective layer is less than about 2 microns. In further embodiments, the thickness of the selective layer is less than about 1 micron.

[0502] In certain embodiments, the thickness of the selective layer is less than about

[0503] 0.9 microns. In further embodiments, the thickness of the selective layer is less than about 0.8 microns. In yet further embodiments, the thickness of the selective layer is less than about 0.7 microns. In still further embodiments, the thickness of the selective layer is less than about 0.6 microns. In certain embodiments, the thickness of the selective layer is less than about 0.5 microns. In further embodiments, the thickness of the selective layer is less than about 0.4 microns. In yet further embodiments, the thickness of the selective layer is less than about 0.3 microns. In still further embodiments, the thickness of the selective layer is less than about 0.2 microns.

[0504] In certain embodiments, the thickness of the selective layer is selected from about about, 0.01 microns, about 0.05 microns, about 0.1 microns, about 0.25 microns, about 0.5 microns, about 0.75 microns, and about 1 micron; preferably wherein the thickness of the selective layer is about 0.0 micron.

[0505] The support layer in the composite membrane is porous. The support layer pore size may be determined using any suitable method known in the art, for example, bubble point test, porosimetry, or scanning electron microscopy. In certain embodiments, the plurality of pores extending through the support layer have a pore size from about 2 nm to about 50 nm. In further embodiments, the plurality of pores extending through the support layer have an average pore size of about 2 nm. In yet further embodiments, the plurality of pores extending through the support layer have an average pore size of about 5 nm. In still further embodiments, the plurality of pores extending through the support layer have an average pore size of about 10 nm. In certain embodiments, the plurality of pores extending through the support layer have an average pore size of about 20 nm. In further embodiments, the plurality of pores extending through the support layer have an average pore size of about 30 nm. In yet further embodiments, the plurality of pores extending through the support layer have an average pore size of about 40 nm. In still further embodiments, the plurality of pores extending through the support layer have an average pore size of about 50 nm.

[0506] In certain embodiments, the thickness of the support layer is from about 15 microns to about 200 microns. In further embodiments, the thickness of the support layer is about

[0507] 15 microns. In yet further embodiments, the thickness of the support layer is about 30 microns. In still further embodiments, the thickness of the support layer is about 45 microns. In certain embodiments, the thickness of the support layer is about 60 microns. In further embodiments, the thickness of the support layer is about 75 microns. In yet further embodiments, the thickness of the support layer is about 90 microns. In still further embodiments, the thickness of the support layer is about 105 microns. In certain embodiments, the thickness of the support layer is about 120 microns. In further embodiments, the thickness of the support layer is about 135 microns. In yet further embodiments, the thickness of the support layer is about 150 microns. In still further embodiments, the thickness of the support layer is about 200 microns.

[0508] In certain embodiments, the thickness of the support layer is selected from about

[0509] 15 microns, about 30 microns, about 45 microns, about 60 microns, about 75 microns, about 90 microns, about 105 microns, about 120 microns, about 135 microns, about 150 microns, about 165 microns, about 180 microns, and about 200 microns; preferably wherein the thickness of the support layer is between about 50 and about 60 microns.

[0510] The support layer can be fabricated from one or more suitable polymers known in the art. In certain embodiments, the support layer comprises a polymer selected from polyethylenimine, polyether ether ketone, polyvinylidene difluoride, polyvinylfluoride, polytetrafluoroethylene, poly(acrylonitrile), polysulfone, cellulose acetate, poly ether sulfone, polycarbonate, polyacrylonitrile, polyethylene terephthalate, and polyimide. In further embodiments, the support layer comprises a plurality of cross-linked polymers.

[0511] In preferred embodiments, the selective layer comprises a copolymer of the disclosure. In certain embodiments, the gutter layer is present. In further embodiments, the gutter layer comprises polysiloxane. In yet further embodiments, the thickness of the gutter layer is from 0.01 microns to about 10 microns. In still further embodiments, the thickness of the gutter layer is about 0.01 microns. In certain embodiments, the thickness of the gutter layer is about 0.1 microns. In further embodiments, the thickness of the gutter layer is about 1 micron. In yet further embodiments, the thickness of the gutter layer is about 2 microns. In still further embodiments, the thickness of the gutter layer is about 3 microns. In certain embodiments, the thickness of the gutter layer is about 4 microns. In further embodiments, the thickness of the gutter layer is about 5 microns. In yet further embodiments, the thickness of the gutter layer is about 6 microns. In still further embodiments, the thickness of the gutter layer is about

[0512] 7 microns. In certain embodiments, the thickness of the gutter layer is about 8 microns. In further embodiments, the thickness of the gutter layer is about 9 microns. In yet further embodiments, the thickness of the gutter layer is about 10 microns. In still further embodiments, the gutter layer is absent.

[0513] In certain embodiments, the composite membrane is in the form of a hollow fiber and the hollow fiber membrane has an outer diameter of from about 90 microns to about 800 microns. In further embodiments, the hollow fiber membrane has an outer diameter of about 90 microns. In yet further embodiments, the hollow fiber membrane has an outer diameter of about

[0514] 200 microns. In certain embodiments, the composite membrane is in the form of a hollow fiber and the hollow fiber has an outer diameter of from about 200 microns to about 800 microns. In further embodiments, the hollow fiber has an outer diameter of about 200 microns. In yet further embodiments, the hollow fiber has an outer diameter of about 300 microns. In still further embodiments, the hollow fiber has an outer diameter of about 400 microns. In yet further embodiments, the hollow fiber has an outer diameter of about 500 microns. In still further embodiments, the hollow fiber has an outer diameter of about 600 microns. In yet further embodiments, the hollow fiber has an outer diameter of about 700 microns. In yet further embodiments, the hollow fiber has an outer diameter of about 800 microns.

[0515] In further embodiments, the composite layer is in the form of a hollow fiber and the hollow fiber has an inner diameter from about 40 microns to about 500 microns. In further embodiments, the hollow fiber membrane has an inner diameter from about 40 microns to about 400 microns, provided the inner diameter is less than the outer diameter. In further embodiments, the hollow fiber has an inner diameter of about 40 microns. In yet further embodiments, the hollow fiber has an inner diameter of about 100 microns. In still further embodiments, the hollow fiber has an inner diameter of about 150 microns. In yet further embodiments, the hollow fiber has an inner diameter of about 200 microns. In still further embodiments, the hollow fiber has an inner diameter of about 250 microns. In yet further embodiments, the hollow fiber has an inner diameter of about 300 microns. In still further embodiments, the hollow fiber has an inner diameter of about 350 microns. In still further embodiments, the hollow fiber has an inner diameter of about 400 microns. In still further embodiments, the hollow fiber has an inner diameter of about 500 microns. Provided the inner diameter is less than the outer diameter.

[0516] In certain embodiments, the ratio of the outer diameter to the inner diameter of the hollow fiber is about 1.1 to about 10. In some embodiments, the ratio of the outer diameter to the inner diameter of the hollow fiber is about 1.5 to about 8, about 1.5 to about 7, about 1.5 to about 6, about 1.5 to about 5, about 1.5 to about 4, about 1.5 to about 3, or about 1.5 to about 2. In some embodiments, the ratio of the outer diameter to the inner diameter of the hollow fiber is about 1.1, about 1.2, about 1.3, about 1.4, about 1.5, about 1.6, about 1.7, about 1.8, about 1.9, about 2, about 2.1, about 2.3, about 2.4, about 1.5, or about 2.6.

[0517] In certain embodiments, the hollow fiber membrane further comprises: a sealing layer comprising a permeable polymer; wherein sealing layer is disposed along the outer surface of the selective layer.

[0518] In certain embodiments, the composite membranes disclosed herein further comprise: a sealing layer comprising a permeable elastic polymer, said sealing layer having a first side, a second side, and a thickness;

[0519] wherein the second side of the selective layer is disposed along the first side of the sealing layer.

[0520] In certain embodiments, the thickness of the sealing layer is from 0.005 microns to about 10 microns. In certain embodiments, the thickness of the sealing layer is from 0.01 microns to about 10 microns. In further embodiments, the thickness of the sealing layer is about

[0521] 0.01 microns. In yet further embodiments, the thickness of the sealing layer is about 0.1 microns. In still further embodiments, the thickness of the sealing layer is about 1 micron. In certain embodiments, the thickness of the sealing layer is about 2 microns. In further embodiments, the thickness of the sealing layer is about 3 microns. In yet further embodiments, the thickness of the sealing layer is about 4 microns. In still further embodiments, the thickness of the sealing layer is about 5 microns. In certain embodiments, the thickness of the sealing layer is about 6 microns. In further embodiments, the thickness of the sealing layer is about 7 microns. In yet further embodiments, the thickness of the sealing layer is about 8 microns. In still further embodiments, the thickness of the sealing layer is about 9 microns. In certain embodiments, the thickness of the sealing layer is about 10 microns. In further embodiments, the sealing layer comprises polysiloxane.

[0522] In certain embodiments, the sealing layer comprises a norbornyl benzocyclobutene polymer, a polysiloxane, a fluorinated polymer, or a combination thereof. In certain embodiments, the hollow fiber membrane consists essentially of the selective layer.

[0523] In certain embodiments, the composite membranes disclosed herein further comprise: a non-woven layer comprising a polymeric material, said non-woven layer having a first side, a second side, and a thickness;

[0524] wherein the second side of the non-woven layer is disposed along the first side of the support layer; and

[0525] the polymeric material is a polyolefin or polyester.

[0526] In certain embodiments, the non-woven layer comprises at least one polyester; optionally wherein the polyester is PET. In further embodiments, the non-woven layer comprises at least one polyolefin. In yet further embodiments, the at least one polyolefin is selected from polyethylene, and polypropylene, or combinations thereof. In still further embodiments, the at least one polyolefin is a combination of polypropylene and polyethylene.

[0527] In certain embodiments, the thickness of the non-woven layer is from about 50 microns to about 300 microns. In further embodiments, the thickness of the non-woven layer is about 50 microns. In yet further embodiments, the thickness of the non-woven layer is about

[0528] 100 microns. In still further embodiments, the thickness of the non-woven layer is about 150 microns. In certain embodiments, the thickness of the non-woven layer is about

[0529] 200 microns. In further embodiments, the thickness of the non-woven layer is about

[0530] 250 microns. In yet further embodiments, the thickness of the non-woven layer is about 300 microns. Monolithic Membranes

[0531] In certain aspects, provided herein are hollow fiber membranes comprising: a selective layer comprising a plurality of polymer chains, said selective layer having an inner surface, an outer surface, and a thickness; wherein the plurality of polymer chains comprises a copolymer of the present disclosure.

[0532] In certain embodiments, provided herein are hollow fiber membranes comprising a copolymer of the present disclosure.

[0533] In some embodiments, the hollow fiber membrane is a monolith. Examples of methods of preparation of the monolithic hollow fiber membranes can be found for example, in U. S. Patent No. 5,085,676, which is incorporated herein by reference in its entirety.

[0534] In certain embodiments, the hollow fiber membrane has an outer diameter from about 90 microns to about 800 microns. In certain embodiments, the hollow fiber membrane has an outer diameter of from about 200 microns to about 800 microns. In further embodiments, the hollow fiber membrane has an outer diameter of about 200 microns. In yet further embodiments, the hollow fiber membrane has an outer diameter of about 300 microns. In still further embodiments, the hollow fiber membrane has an outer diameter of about 400 microns. In yet further embodiments, the hollow fiber membrane has an outer diameter of about 500 microns. In still further embodiments, the hollow fiber membrane has an outer diameter of about

[0535] 600 microns. In yet further embodiments, the hollow fiber membrane has an outer diameter of about 700 microns. In yet further embodiments, the hollow fiber membrane has an outer diameter of about 800 microns.

[0536] In further embodiments, the hollow fiber membrane has an inner diameter from about 40 microns to about 500 microns, provided the inner diameter is less than the outer diameter. In further embodiments, the hollow fiber membrane has an inner diameter from about 50 microns to about 400 microns. In further embodiments, the hollow fiber membrane has an inner diameter of about 50 microns. In yet further embodiments, the hollow fiber membrane has an inner diameter of about 100 microns. In still further embodiments, the hollow fiber membrane has an inner diameter of about 150 microns. In yet further embodiments, the hollow fiber membrane has an inner diameter of about 200 microns. In still further embodiments, the hollow fiber membrane has an inner diameter of about 250 microns. In yet further embodiments, the hollow fiber membrane has an inner diameter of about 300 microns. In still further embodiments, the hollow fiber membrane has an inner diameter of about 350 microns. In still further embodiments, the hollow fiber membrane has an inner diameter of about 400 microns. Provided the inner diameter is less than the outer diameter.

[0537] In certain embodiments, the hollow fiber membrane is selective for separating CH₄ from He. In certain embodiments, the hollow fiber membrane is selective for separating H₂ from N₂.

[0538] Methods of Making Membranes

[0539] In certain aspects, provided herein are methods of preparing a composite membrane of the present disclosure.

[0540] In certain embodiments, the method of preparing a composite membrane of the present disclosure comprises:

[0541] providing a porous support in the form of a hollow fiber; and

[0542] coating the hollow fiber with the selective solution, thereby forming the hollow fiber composite membrane.

[0543] In some aspects, provided herein are methods of preparing a hollow fiber membrane of the present disclosure.

[0544] In certain embodiments, the method of preparing a composite membrane of the present disclosure comprises:

[0545] providing a support mixture comprising a support polymer precursor, a first solvent, and a second solvent, the support mixture having a first solvent: second solvent ratio; contacting the support mixture with a substrate, thereby forming a nascent support; degassing the nascent support, the thereby forming a porous support;

[0546] spinning the porous support into a hollow fiber;

[0547] washing and cross-linking the hollow fiber;

[0548] coating the hollow fiber with the selective solution, thereby forming the hollow fiber composite membrane. Methods of Separating Fluids

[0549] In yet further aspects, provided herein are methods for separating a mixture of fluids comprising a first fluid and a second fluid, the methods comprising:

[0550] contacting a fluid mixture with a copolymer, a composite membrane, or a hollow fiber membrane of the present disclosure, thereby separating the mixture of fluids into:

[0551] a permeate comprising a first portion of the first fluid and a first portion of the second fluid; and a retentate comprising a second portion of the second fluid.

[0552] As will be appreciated, the efficiency and selectivity of such separations will be affected by any number of process parameters, including the initial composition of the mixture of fluids, pressures, temperatures, etc. Additionally, as will be apparent to one of skill in the art, when describing percentages that are greater than or less than (or higher or lower than) other percentages, this describes an additive or subtractive change in the total percentage. For instance, for a mixture of fluids comprising 50% of the first fluid and 50% of the second fluid, where the percentage of the first fluid is said to increase by 5%, this would result in a mixture comprising 55% first fluid.

[0553] In certain embodiments, the volume percent of the first fluid in the permeate is higher than the volume percent of the first fluid in the mixture of fluids by about 1% to about 99%. In further embodiments, the volume percent of the first fluid in the permeate is higher than the volume percent of the first fluid in the mixture of fluids by at least about 1%, about 5%, about 10%, about 20%, about 30%, about 40%, about 50%, about 60%, about 70%, about 80%, about 90%, about 95%, about 97.5%, or about 99%. In yet further embodiments, the volume percent of the first fluid in the permeate is higher than the volume percent of the first fluid in the mixture of fluids by at most about 1%, about 5%, about 10%, about 20%, about 30%, about 40%, about 50%, about 60%, about 70%, about 80%, about 90%, about 95%, about 97.5%, or about 99%. In yet further embodiments, the volume percent of the first fluid in the permeate is higher than the volume percent of the first fluid in the mixture of fluids by about 1%, about 5%, about 10%, about 20%, about 30%, about 40%, about 50%, about 60%, about 70%, about 80%, about 90%, about 95%, about 97.5%, or about 99%.

[0554] In certain embodiments, the volume percent of the second fluid in the permeate is lower than the volume percent of the second fluid in the mixture of fluids by about 1% to about 99%. In further embodiments, the volume percent of the second fluid in the permeate is lower than the volume percent of the second fluid in the mixture of fluids by at least about 1%, about 5%, about 10%, about 20%, about 30%, about 40%, about 50%, about 60%, about 70%, about 80%, about 90%, about 95%, about 97.5%, or about 99%. In yet further embodiments, the volume percent of the second fluid in the permeate is lower than the volume percent of the second fluid in the mixture of fluids by at most about 1%, about 5%, about 10%, about 20%, about 30%, about 40%, about 50%, about 60%, about 70%, about 80%, about 90%, about 95%, about 97.5%, or about 99%. In still further embodiments, the volume percent of the second fluid in the permeate is lower than the volume percent of the second fluid in the mixture of fluids by about 1%, about 5%, about 10%, about 20%, about 30%, about 40%, about 50%, about 60%, about 70%, about 80%, about 90%, about 95%, about 97.5%, or about 99%.

[0555] In certain embodiments, the volume percent of the first fluid in the permeate is from about 99% to about 1%. In further embodiments, the volume percent of the first fluid in the permeate is greater than about 99%, about 95%, about 90%, about 80%, about 70%, about 60%, about 50%, about 40%, about 30%, about 20%, about 10%, about 5%, about 2.5%, and about 1%; optionally wherein volume percent of the first fluid in the permeate is greater than about 95%. In yet further embodiments, the volume percent of the first fluid in the permeate is less than about 99%, about 95%, about 90%, about 80%, about 70%, about 60%, about 50%, about 40%, about 30%, about 20%, about 10%, about 5%, about 2.5%, and about 1%; optionally wherein volume percent of the first fluid in the permeate is less than about 95%. In still further embodiments, the volume percent of the first fluid in the permeate is about 99%, about 95%, about 90%, about 80%, about 70%, about 60%, about 50%, about 40%, about 30%, about 20%, about 10%, about 5%, about 2.5%, and about 1%; optionally wherein volume percent of the first fluid in the permeate is about 95%.

[0556] In certain embodiments, the volume percent of the second fluid in the permeate is from about 99% to about 1%. In further embodiments, the volume percent of the second fluid in the permeate is less than about 99%, about 95%, about 90%, about 80%, about 70%, about 60%, about 50%, about 40%, about 30%, about 20%, about 10%, about 5%, about 2.5%, and about 1%; optionally wherein volume percent of the second fluid in the permeate is less than about 5%. In yet further embodiments, the volume percent of the second fluid in the permeate is greater than about 99%, about 95%, about 90%, about 80%, about 70%, about 60%, about 50%, about 40%, about 30%, about 20%, about 10%, about 5%, about 2.5%, and about 1%; optionally wherein volume percent of the second fluid in the permeate is greater than about 5%. In still further embodiments, the volume percent of the second fluid in the permeate is about 99%, about 95%, about 90%, about 80%, about 70%, about 60%, about 50%, about 40%, about 30%, about 20%, about 10%, about 5%, about 2.5%, and about 1%; optionally wherein volume percent of the second fluid in the permeate is about 5%.

[0557] In certain embodiments, the volume of the first fluid in the permeate is higher than about 10% to about 99% by volume of the first fluid in the mixture of fluids. In further embodiments, the volume of the first fluid in the permeate is higher than about 10% by volume, about 20% by volume, about 30% by volume, about 40% by volume, about 50% by volume, about 60% by volume, about 70% by volume, about 80% by volume, about 90% by volume, about 95% by volume, about 98% by volume, or about 99% by volume of the volume of the first fluid in the mixture of fluids; optionally wherein the volume of the first fluid in the permeate is higher than about 80% of the volume of the first fluid in the mixture of fluids. In yet further embodiments, the volume of the first fluid in the permeate is lower than about 10% by volume, about 20% by volume, about 30% by volume, about 40% by volume, about 50% by volume, about 60% by volume, about 70% by volume, about 80% by volume, about 90% by volume, about 95% by volume, about 98% by volume, or about 99% by volume of the volume of the first fluid in the mixture of fluids; optionally wherein the volume of the first fluid in the permeate is lower than about 80% of the volume of the first fluid in the mixture of fluids. In still further embodiments, the volume of the first fluid in the permeate is about 10% by volume, about 20% by volume, about 30% by volume, about 40% by volume, about 50% by volume, about 60% by volume, about 70% by volume, about 80% by volume, about 90% by volume, about 95% by volume, about 98% by volume, or about 99% by volume of the volume of the first fluid in the mixture of fluids; optionally wherein the volume of the first fluid in the permeate is about 80% of the volume of the first fluid in the mixture of fluids.

[0558] In certain embodiments, the first fluid is He, and the second fluid is CH₄. In further embodiments, the first fluid is H₂, and the second fluid is N₂. In some embodiments, the first fluid is H₂ and the second fluid is N₂. In some embodiments, the first fluid is He and the second fluid is N₂. In some embodiments, the first fluid is He and H₂, and the second fluid is N₂.

[0559] In certain embodiments, the pores of the support member are substantially parallel to the direction of fluid flow through the composite membrane (i.e., direct flow separation). In further embodiments, the pores of the support member are substantially perpendicular to the direction of fluid flow through the composite membrane (i.e., tangential flow separation).

[0560] In certain embodiments, provided herein are methods of separating a mixture of fluids, wherein the fluid mixture is contacted with a hollow fiber membrane of the present disclosure; and the direction of fluid flow through the hollow fiber membrane is through the thickness of the selective layer (i.e., direct flow separation). In further embodiments, the fluid mixture is contacted with a hollow fiber membrane of the present disclosure; and the direction of fluid flow through the hollow fiber membrane is along the inner surface or along the outer surface of the selective layer (i.e., tangential flow separation).

[0561] Gas Permeability

[0562] Gas permeability which may be expressed in the unit Barrer, which is defined as: 1 Barrer = 1010-cm3[at STP] •cm-cm’2-s1-cmHg1. The permeability for all copolymers described in the present disclosure is an intrinsic property for each of the copolymers. The composite membranes or hollow fiber membranes of the present disclosure exhibit gas permeance for particular gases which may be expressed in the unit permeance (in gas permeation units, GPU) multiplied by film thickness in pm, where 1 GPU = 10-6cm3(STP) / (cm2s cm Hg). By definition, the permeability (in Barrer) divided by selective layer thickness in μm defines the permeance (in gas permeation units, GPU), where 1 GPU = 10-6cm3(STP) / (cm2s cm Hg).

[0563] In certain embodiments, the composite membrane or hollow fiber membrane has a gas permeance for H₂ (PH2) from about 50 GPU to about 3500 GPU. In further embodiments, the composite membrane or hollow fiber membrane has a gas permeance for H₂ (PH2) from about 50 GPU to about 100 GPU. In yet further embodiments, the composite membrane or hollow fiber membrane has a gas permeance for H₂ (PH2) from about 100 GPU to about 199 GPU. In still further embodiments, the composite membrane or hollow fiber membrane has a gas permeance for H₂ (PH2) from about 200 GPU to about 499 GPU. In certain embodiments, the composite membrane or hollow fiber membrane has a gas permeance for H₂ (PH2) from about 500 GPU to about 999 GPU. In further embodiments, the composite membrane or hollow fiber membrane has a gas permeance for H₂ (PH2) from about 1000 GPU to about 1499 GPU. In yet further embodiments, the composite membrane or hollow fiber membrane has a gas permeance for H₂ (PH2) from about 1500 GPU to about 1999 GPU. In still further embodiments, the composite membrane or hollow fiber membrane has a gas permeance for H₂ (PH2) from about 2000 GPU to about 3500 GPU.

[0564] In certain embodiments, the composite membrane or hollow fiber membrane has a gas permeance for H2 (PH2) of about 50 GPU. In further embodiments, the composite membrane or hollow fiber membrane has a gas permeance for H2 (PH2) of about 100 GPU. In yet further embodiments, the composite membrane or hollow fiber membrane has a gas permeance for H2(PH2) of about 250 GPU. In still further embodiments, the composite membrane or hollow fiber membrane has a gas permeance for H2(PH2) of about 500 GPU. In certain embodiments, the composite membrane or hollow fiber membrane has a gas permeance for H2(PH2) of about 750 GPU. In further embodiments, the composite membrane or hollow fiber membrane has a gas permeance for H2(PH2) of about 1000 GPU. In yet further embodiments, the composite membrane or hollow fiber membrane has a gas permeance for H2(PH2) of about 1250 GPU. In still further embodiments, the composite membrane or hollow fiber membrane has a gas permeance for H2(PH2) of about 1500 GPU. In certain embodiments, the composite membrane or hollow fiber membrane has a gas permeance for H2(PH2) of about 1750 GPU. In further embodiments, the composite membrane or hollow fiber membrane has a gas permeance for H2(PH2) of about 2000 GPU. In yet further embodiments, the composite membrane or hollow fiber membrane has a gas permeance for H2 (PH2) of about 2250 GPU. In still further embodiments, the composite membrane or hollow fiber membrane has a gas permeance for H2 (PH2) of about 2500 GPU. In certain embodiments, the composite membrane or hollow fiber membrane has a gas permeance for H2 (PH2) of about 2750 GPU. In further embodiments, the composite membrane or hollow fiber membrane has a gas permeance for H2 (PH2) of about 3000 GPU. In yet further embodiments, the composite membrane or hollow fiber membrane has a gas permeance for H2 (PH2) of about 3250 GPU. In certain embodiments, the composite membrane or hollow fiber membrane has a gas permeance for He (PHe) from about 45 GPU to about 3000 GPU. In some embodiments, the composite membrane or hollow fiber membrane has a gas permeance for He (PHe) from about 45 GPU to about 99 GPU. In further embodiments, the composite membrane or hollow fiber membrane has a gas permeance for He (PHe) from about 100 GPU to about 149 GPU. In yet further embodiments, the composite membrane or hollow fiber membrane has a gas permeance for He (PHe) from about 150 GPU to about 299 GPU. In still further embodiments, the composite membrane or hollow fiber membrane has a gas permeance for He (PHe) from about 300 GPU to about 599 GPU. In certain embodiments, the composite membrane or hollow fiber membrane has a gas permeance for He (PHe) from about 600 GPU to about 749 GPU. In further embodiments, the composite membrane or hollow fiber membrane has a gas permeance for He (PHe) from about 750 GPU to about 999 GPU. In yet further embodiments, the composite membrane or hollow fiber membrane has a gas permeance for He (PHe) from about 1000 GPU to about 3000 GPU.

[0565] In certain embodiments, the composite membrane or hollow fiber membrane has a gas permeance for He (PHe) of about 45 GPU. In further embodiments, the composite membrane or hollow fiber membrane has a gas permeance for He (PHe) of about 75 GPU. In yet further embodiments, the composite membrane or hollow fiber membrane has a gas permeance for He (PHe) of about 100 GPU. In still further embodiments, the composite membrane or hollow fiber membrane has a gas permeance for He (PHe) of about 125 GPU. In certain embodiments, the composite membrane or hollow fiber membrane has a gas permeance for He (PHe) of about 150 GPU. In further embodiments, the composite membrane or hollow fiber membrane has a gas permeance for He (PHe) of about 175 GPU. In yet further embodiments, the composite membrane or hollow fiber membrane has a gas permeance for He (PHe) of about 200 GPU. In still further embodiments, the composite membrane or hollow fiber membrane has a gas permeance for He (PHe) of about 225 GPU. In certain embodiments, the composite membrane or hollow fiber membrane has a gas permeance for He (PHe) of about 250 GPU. In further embodiments, the composite membrane or hollow fiber membrane has a gas permeance for He (PHe) of about 275 GPU. In yet further embodiments, the composite membrane or hollow fiber membrane has a gas permeance for He (PHe) of about 300 GPU. In still further embodiments, the composite membrane or hollow fiber membrane has a gas permeance for He (PHe) of about 325 GPU. In certain embodiments, the composite membrane or hollow fiber membrane has a gas permeance for He (PHe) of about 350 GPU. In further embodiments, the composite membrane or hollow fiber membrane has a gas permeance for He (PHe) of about 375 GPU. In yet further embodiments, the composite membrane or hollow fiber membrane has a gas permeance for He (PHe) of about 400 GPU. In still further embodiments, the composite membrane or hollow fiber membrane has a gas permeance for He (PHe) of about 450 GPU. In certain embodiments, the composite membrane or hollow fiber membrane has a gas permeance for He (PHe) of about 500 GPU. In further embodiments, the composite membrane or hollow fiber membrane has a gas permeance for He (PHe) of about 550 GPU. In yet further embodiments, the composite membrane or hollow fiber membrane has a gas permeance for He (PHe) of about 600 GPU. In still further embodiments, the composite membrane or hollow fiber membrane has a gas permeance for He (PHe) of about 650 GPU. In certain embodiments, the composite membrane or hollow fiber membrane has a gas permeance for He (PHe) of about 700 GPU. In further embodiments, the composite membrane or hollow fiber membrane has a gas permeance for He (PHe) of about 750 GPU. In yet further embodiments, the composite membrane or hollow fiber membrane has a gas permeance for He (PHe) of about 875 GPU. In still further embodiments, the composite membrane or hollow fiber membrane has a gas permeance for He (PHe) of about 1000 GPU. In certain embodiments, the composite membrane or hollow fiber membrane has a gas permeance for He (PHe) of about 1500 GPU. In further embodiments, the composite membrane or hollow fiber membrane has a gas permeance for He (PHe) of about 2000 GPU. In yet further embodiments, the composite membrane or hollow fiber membrane has a gas permeance for He (PHe) of about 2500 GPU. In still further embodiments, the composite membrane or hollow fiber membrane has a gas permeance for He (PHe) of about 3000 GPU.

[0566] In certain embodiments, the composite membrane or hollow fiber membrane is selective for separating H2 from CH4. In some embodiments, the selectivity of the composite membrane or hollow fiber membrane (PH2 / PCH4) is from about 1 to about 700. In further embodiments, the selectivity of the composite membrane or hollow fiber membrane (PH2 / PCH4) is from about 1 to about 9.9. In yet further embodiments, the selectivity of the composite membrane or hollow fiber membrane (PH2 / PCH4) is from about 10 to about 29.9. In still further embodiments, the selectivity of the composite membrane or hollow fiber membrane (PH2 / PCH4) is from about 30 to about 69.9. In certain embodiments, the selectivity of the composite membrane or hollow fiber membrane (PH2 / PCH4) is from about 70 to about 99.9. In further embodiments, the selectivity of the composite membrane or hollow fiber membrane (PH2 / PCH4) is from about 100 to about 149.9. In yet further embodiments, the selectivity of the composite membrane or hollow fiber membrane (PH2 / PCH4) is from about 150 to about 299.9. In still further embodiments, the selectivity of the composite membrane or hollow fiber membrane (PH2 / PCH4) is from about 300 to about 700.

[0567] In certain embodiments, the selectivity of the composite membrane or hollow fiber membrane (PH2 / PCH4) is about 4. In further embodiments, the selectivity of the composite membrane or hollow fiber membrane (PH2 / PCH4) is about 25. In yet further embodiments, the selectivity of the composite membrane or hollow fiber membrane (PH2 / PCH4) is about 50. In still further embodiments, the selectivity of the composite membrane or hollow fiber membrane (PH2 / PCH4) is about 75. In certain embodiments, the selectivity of the composite membrane or hollow fiber membrane (PH2 / PCH4) is about 100. In further embodiments, the selectivity of the composite membrane or hollow fiber membrane (PH2 / PCH4) is about 125. In yet further embodiments, the selectivity of the composite membrane or hollow fiber membrane (PH2 / PCH4) is about 150. In still further embodiments, the selectivity of the composite membrane or hollow fiber membrane (PH2 / PCH4) is about 175. In certain embodiments, the selectivity of the composite membrane or hollow fiber membrane (PH2 / PCH4) is about 200. In further embodiments, the selectivity of the composite membrane or hollow fiber membrane (PH2 / PCH4) is about 250. In yet further embodiments, the selectivity of the composite membrane or hollow fiber membrane (PH2 / PCH4) is about 300. In still further embodiments, the selectivity of the composite membrane or hollow fiber membrane (PH2 / PCH4) is about 400. In certain embodiments, the selectivity of the composite membrane or hollow fiber membrane (PH2 / PCH4) is about 500. In further embodiments, the selectivity of the composite membrane or hollow fiber membrane (PH2 / PCH4) is about 600. In yet further embodiments, the selectivity of the composite membrane or hollow fiber membrane (PH2 / PCH4) is about 700.

[0568] In certain embodiments, the composite membrane or hollow fiber membrane is selective for separating He from N2. In some embodiments, the selectivity of the composite membrane or hollow fiber membrane (PHe / PN2) is from about 0.1 to about 450. In further embodiments, the selectivity of the composite membrane or hollow fiber membrane (PHe / PN2) is from about 0.1 to about 19.9. In yet further embodiments, the selectivity of the composite membrane or hollow fiber membrane (PHe / PN2) is from about 20 to about 39.9. In still further embodiments, the selectivity of the composite membrane or hollow fiber membrane (PHe / PN2) is from about 40 to about 49.9. In certain embodiments, the selectivity of the composite membrane or hollow fiber membrane (PHe / PN2) is from about 50 to about 99.9. In further embodiments, the selectivity of the composite membrane or hollow fiber membrane (PHe / PN2) is from about 100 to about 249.9. In yet further embodiments, the selectivity of the composite membrane or hollow fiber membrane (PHe / PN2) is from about 250 to about 450.

[0569] In certain embodiments, the selectivity of the composite membrane or hollow fiber membrane (PHe / PN2) is about 5. In further embodiments, the selectivity of the composite membrane or hollow fiber membrane (PHe / PN2) is about 20. In yet further embodiments, the selectivity of the composite membrane or hollow fiber membrane (PHe / PN2) is about 30. In still further embodiments, the selectivity of the composite membrane or hollow fiber membrane (PHe / PN2) is about 40. In certain embodiments, the selectivity of the composite membrane or hollow fiber membrane (PHe / PN2) is about 50. In further embodiments, the selectivity of the composite membrane or hollow fiber membrane (PHe / PN2) is about 60. In yet further embodiments, the selectivity of the composite membrane or hollow fiber membrane (PHe / PN2) is about 75. In still further embodiments, the selectivity of the composite membrane or hollow fiber membrane (PHe / PN2) is about 125. In certain embodiments, the selectivity of the composite membrane or hollow fiber membrane (PHe / PN2) is about 175. In further embodiments, the selectivity of the composite membrane or hollow fiber membrane (PHe / PN2) is about 200. In yet further embodiments, the selectivity of the composite membrane or hollow fiber membrane (PHe / PN2) is about 250. In still further embodiments, the selectivity of the composite membrane or hollow fiber membrane (PHe / PN2) is about 300. In certain embodiments, the selectivity of the composite membrane or hollow fiber membrane (PHe / PN2) is about 350. In further embodiments, the selectivity of the composite membrane or hollow fiber membrane (PHe / PN2) is about 400. In yet further embodiments, the selectivity of the composite membrane or hollow fiber membrane (PHe / PN2) is about 425. In still further embodiments, the selectivity of the composite membrane or hollow fiber membrane (PHe / PN2) is about 450. In certain embodiments, the composite membrane or hollow fiber membrane is selective for separating H2 from CO2. In some embodiments, the selectivity of the composite membrane or hollow fiber membrane (PH2 / PC02) is from about 0.5 to about 25. In certain embodiments, the selectivity of the composite membrane or hollow fiber membrane (PH2 / PC02) is infinite (i.e. wherein PH2 is a non-zero positive number, and Pco2 is essentially zero). In further embodiments, the selectivity of the composite membrane or hollow fiber membrane (PH2 / PC02) is from about 0.5 to about 0.9. In yet further embodiments, the selectivity of the composite membrane or hollow fiber membrane (PH2 / PC02) is from about 1.0 to about 1.9. In still further embodiments, the selectivity of the composite membrane or hollow fiber membrane (PH2 / PC02) is from about 2.0 to about 2.9. In certain embodiments, the selectivity of the composite membrane or hollow fiber membrane (PH2 / PC02) is from about 3 to about 3.9. In further embodiments, the selectivity of the composite membrane or hollow fiber membrane (PH2 / PC02) is from about 4 to about 9.9. In yet further embodiments, the selectivity of the composite membrane or hollow fiber membrane (PH2 / PC02) is from about 10 to about 25.

[0570] In certain embodiments, the selectivity of the composite membrane or hollow fiber membrane (PH2 / PC02) is about 1. In further embodiments, the selectivity of the composite membrane or hollow fiber membrane (PH2 / PC02) is about 3. In yet further embodiments, the selectivity of the composite membrane or hollow fiber membrane (PH2 / PC02) is about 5. In still further embodiments, the selectivity of the composite membrane or hollow fiber membrane (PH2 / PC02) is about 10. In certain embodiments, the selectivity of the composite membrane or hollow fiber membrane (PH2 / PC02) is about 15. In further embodiments, the selectivity of the composite membrane or hollow fiber membrane (PH2 / PC02) is about 20. In yet further embodiments, the selectivity of the composite membrane or hollow fiber membrane (PH2 / PC02) is about 25.

[0571] The invention now being generally described, it will be more readily understood by reference to the following examples which are included merely for purposes of illustration of certain aspects and embodiments of the present invention, and are not intended to limit the invention. Example 1: Synthesis of a Representative Polyimide-Type Polymer

[0572]

[0573] In an oven-dried Schlenk tube equipped with a magnetic stirrer and under a steady flow of N2 584mg (1.0mmol) of diamine monomer and 444mg (1.0mmol) of 4,4'-(Hexafluoro-isopropylidene) diphthalic anhydride (6FDA) were added. After purging the tube for 10min at room temperature, 2.3mL of m-cresol and 5-6 drops of isoquinoline were added, and the temperature was raised to 100°C while stirred. After the reaction system was dissolved completely, the temperature was further adjusted to 190 °C. After 4 hours, a viscous polymer solution was obtained, the reaction was then terminated and diluted with 5 ml CHCI3. The desired polyimide was precipitated in ethanol. The resulting fibrous precipitate was obtained by washing with ethanol several times, and drying overnight at 120 °C under vacuum.

[0574] ’H-NMR (CDCI3, 400 MHz, 8): 8.03 (d, J = 7.9 Hz, 1H), 7.91 (s, 2H), 7.34 (t, J = 9.5 Hz, 1H), 7.10-7.04 (m, 1H), 7.01 (d, J = 13.3 Hz, 2H), 3.31 (s, 4H), 2.46 (d, J = 22.9 Hz, 2H), 2.07 (s, 3H), 1.58 (brs, 3H), 1.48-1.40 (m, 3H), 0.89 (s, 2H).

[0575] Example 2: Characterization of Exemplary Polymer 5

[0576]

[0577] ¹H NMR (500 MHz, CDCl₃) δ 8.04 (s, 2H), 7.94 (s, 4H), 7.70 (s, 2H), 7.56 – 7.45 (m, 2H), 7.37 (s, 3H), 6.93 – 6.74 (m, 3H), 6.61 (d, J = 46.0 Hz, 2H), 6.36 (d, J = 10.8 Hz, 2H), 3.37 – 3.11 (m, 8H), 2.46 (d, J = 9.7 Hz, 2H), 2.22 (d, J = 13.4 Hz, 3H), 2.14 (d, J = 10.1 Hz, 6H), 1.99 (d, J = 40.0 Hz, 6H), 1.25 - 1.04 (m, 17H), 0.83 (d, J = 47.7 Hz, 4H).

[0578] Example 10: Characterization of Exemplary Polymer 6

[0579]

[0580] ¹H NMR (500 MHz, CDCl₃) δ 8.04 (s, 2H), 7.92 (s, 5H), 7.75 – 7.65 (m, 2H), 7.50 (t, J = 9.0 Hz, 2H), 7.46 – 7.31 (m, 2H), 6.98 (d, J = 32.7 Hz, 4H), 6.78 (t, J = 26.2 Hz, 3H), 6.66 (s, 1H), 6.35 (d, J = 5.6 Hz, 2H), 3.39 – 3.13 (m, 8H), 2.54 – 2.40 (m, 2H), 2.25 (d, J = 16.4 Hz, 2H), 2.10 (d, J = 14.3 Hz, 4H), 2.02 (d, J = 16.1 Hz, 3H), 1.29 – 1.05 (m, 18H), 0.81 (d, J = 31.1 Hz, 4H).

[0581] Example 3: Characterization of Exemplary Polymer 7a and 7b

[0582]

[0583] ¹H NMR (500 MHz, CDCl₃) δ 8.07 (d, J = 6.9 Hz, 2H), 8.00 – 7.86 (m, 4H), 7.47 (s, 2H), 7.43 – 7.31 (m, 2H), 7.28 – 7.23 (m, 2H), 7.16 – 7.02 (m, 3H), 3.51 (d, J = 22.1 Hz, 4H), 3.37 (d, J = 15.4 Hz, 4H), 2.64 – 2.51 (m, 4H), 1.46 (d, J = 12.8 Hz, 7H), 1.07 – 0.80 (m, 5H).

[0584]

[0585] ¹H NMR (500 MHz, CDCl₃) δ 8.11 – 7.98 (m, 2H), 7.92 (s, 2H), 7.84 (s, 2H), 7.48 (d, J = 7.3 Hz, 2H), 7.37 (d, J = 10.1 Hz, 2H), 7.13 (d, J = 10.9 Hz, 2H), 6.98 (d, J = 33.2 Hz, 3H), 6.79

[0586]

[0587] ¹H NMR (500 MHz, CDCl₃) δ 8.05 (d, J = 7.2 Hz, 2H), 7.99 – 7.87 (m, 4H), 7.78 – 7.71 (m, 2H), 7.44 (d, J = 11.4 Hz, 2H), 7.04 (t, J = 9.6 Hz, 4H), 3.34 (d, J = 16.6 Hz, 8H), 2.93 (s, 4H), 2.57 – 2.45 (m, 4H), 2.20 (s, 3H), 2.15 – 2.05 (m, 6H), 2.00 (s, 3H), 1.78 (s, 5H), 1.01 – 0.88 (m, 4H).

[0588] Example 7: General Procedure for Obtaining Performance Data of Exemplary Hollow Fiber Membranes

[0589] The permeance (in GPU) was tested for a selection of exemplary Hollow Fiber Membranes made according to methods of Examples 27-29. Single-gas permeation experiments were performed at pressures from about 1 bar to about 50 bar and temperatures from about 25 °C to about 100 °C. Example 8: Characterization of exemplary polymer 11

[0590]

[0591] ¹H NMR (500 MHz, CDCl₃) δ 8.07 (d, J = 8.1 Hz, 2H), 7.96 (s, 4H), 7.38 (q, J = 11.7 Hz, 2H), 6.89 (d, J = 10.6 Hz, 4H), 3.45 – 3.18 (m, 8H), 2.82 (s, 4H), 2.44 (d, J = 13.0 Hz, 4H), 2.24 – 2.09 (m, 6H), 2.03 (d, J = 5.0 Hz, 6H), 1.03 – 0.89 (m, 4H).

[0592] Example 9: Synthesis of Exemplary Diamine

[0593] To an oven-dried sealed round-bottom flask (RBF) equipped with a magnetic stirrer, di(adamantan-l-yl)(tert-butyl)phosphine ligand (0.04 eq / mmol), and Pd(OAc)2 (0.02eq / mmol) were added.

[0594] The flask was transferred into an inert atmosphere glovebox, were added, in order, oven dried K2CO3 (2.2 eq / mmol), 1,4-dioxane (1.5 ml / mmol), freshly distilled 3-bromo-2-methylaniline (2.0 eq / mmol) and bicyclo[2.2.1]hepta-2,5-diene (NBD, CAS: 121-46-0, 1.0 eq).

[0595] The flask was sealed with a Teflon cap and removed from the glovebox, and the resulting mixture was stirred at 110 °C for 48 hours.

[0596] The mixture was subsequently cooled to ambient temperature. The cooled mixture was filtered through a thin pad of Celite™ ( / .<?., diatomaceous earth) to remove inorganic salts and washed with dichloromethane. The solvent was evaporated under reduced pressure, and the resulting mixture dried under vacuum and purified by chromatography on silica to afford a white-off white solid.

[0597] TLC: 50% ethyl acetate in hexanes (dye in ninhydrin stain); Rf: 0.45

[0598] Elution: 40-80% ethyl acetate in hexanes [yield: 90%]

[0599] Example 10: General Procedure for Synthesis of Representative Co-Polymer

[0600] Cool a jacketed reactor to 0 °C. Add all the substrates / co-monomers (1 eq) and 6-FDA (1 eq) to the reactor and purge with N2 for at least 15 min. Continue purging with N2, add NMP (2 ml / mmol), and stir until all the solids are fully dissolved. Stir for about 4 hours, adjusting speed as necessary. If the solution becomes too viscous to stir well, add extra NMP (~0.5ml / mmol). Continue N2 purging for at least 2 hours, and keep chiller on for the whole 4 hours of this step.

[0601] After 4 hours, begin N2 purging again. While stirring, add pyridine (4 eq), and followed by acetic anhydride (4 eq). Close the reactor and purge for at least 1 hour to maintain an air free atmosphere. Continue stirring for 3 hours.

[0602] Work up / Quench:

[0603] To the completed reaction, add THF (approximately 5 mL / mmol, adjust as necessary based on viscosity) and stir until fully dissolved. Slowly precipitate polymer solution into stirred IPA. Filter the precipitate through Buchner funnel, wash with IP A, and dry at 120 °C under vacuum. [Polymer will be obtained as off white to yellow, fibrous solid.].

[0604] Example 11: Synthesis of a Representative Polvimide-Tvpe Polymer

[0605] A jacketed reactor was cooled to 0 °C. To the reactor were added 1 eq each of Osmoses Substrate II (structure shown below), / / / -phenylene diamine, 3,5-diamino benzoic acid, and 6-FDA (CAS No. 1107-00-2). The reactor was purged with N2 for about 15 min. NMP

[0606] (2 ml / mmol) was added to the reactor while N2 purging was continued, and the resulting mixture was stirred until all solids were fully dissolved. The resulting solution was stirred for about 4 hours, with the N2 purging maintained for at about the first 2 h, and stirring speed was adjusted as necessary. The reactor was kept at 0 C during the entire 4 hours.

[0607] After 4 hours of stirring, N2 purging was begun again. While stirring, pyridine (4 eq) was added, followed by acetic anhydride (4 eq). The reactor was closed and purged with N2 for at least 1 hour to maintain the inert atmosphere. Stirring was continued for 3 hours.

[0608] Work up / Quench:

[0609] To the completed reaction, THF was added (approximately 5 mL / mmol, adjusted as necessary based on viscosity) and the resulting mixture stirred until fully dissolved. The resulting solution was slowly added to isopropanol while stirring, to precipitate polymer solution. The resulting mixture was passed through a Buchner funnel. The solids were collected, washed with isopropanol, and dried at 120 °C under vacuum. The desired copolymer was obtained as an off white to yellow, fibrous solid.

[0610]

[0611] units in polymer

[0612]

[0613] Chemical shifts of the polyimide were measured by Bruker AVANCE NEO 500 NMR spectrometer and samples were dissolved in DMSO or chloroform prior to testing. The relative molecular weight of poly imides was obtained by gel permeation chromatography (Tosoh HLC-8420GPC) with N-methyl pyrrolidinone as the mobile phase.

[0614] ¹H NMR (500 MHz, DMSO-d₆) δ 8.19 (d, J 8.3 Hz, 1.7H), 8.16 (d, J 2.1 Hz, 1H), 7.96 (d, J 8.0 Hz, 2H), 7.86 (s, 0.4H), 7.81 (s, 0.4H), 7.78 (s, 1.7H), 7.70 (t, J 7.8 Hz, 0.4H), 7.57 (d, J 11.2 Hz, 1.3H), 7.20 (s, 0.5H), 7.03 (s, 0.5H).

[0615] Molecular weight: Mn = 9.8xl04g / mol; Mw = 19.5xl04g / mol; PDI = 2.0.

[0616] Example 13: General Procedure for Preparation of Monolithic Flat Sheet “Thick” Films Polymer solutions (0.75 wt / vol%) of a copolymer of the disclosure in chloroform or tetrahydrofuran were filtered through 0.45 pm PTFE filters and poured into flat glass Petri dishes. The polymer solutions were evaporated at room temperature in one day. Once dried, films were soaked in water until fully detached from the dishes. The polymer films were further dried at 120 °C for 24 h under vacuum. The films were then soaked in methanol for 24 h, air dried, and then dried at 180 °C in a vacuum oven for 24 h. Film thicknesses and areas were measured by a digital micrometer and a scanner, respectively.

[0617] Example 14: Support Dope Preparation for Film Composites - Method 1

[0618] To a glass jar with a screw top lid was added Ultem 1000 powder previously dried in a vacuum oven at 110 °C overnight (30 g), / V-methy 1 pyrrol idi none (99 mL), anhydrous THF (16.9 mL), water (1.5 mL), and lithium nitrate (1.5 g). The jar was capped and placed on rollers until a homogenous solution was obtained. The solution was stood upright and allowed to degas for at least 24 hours and stored in a desiccator until use. This provided a dope that is 20% Ultem, 68% NMP, 10% THF, 1% water, 1% lithium nitrate by weight.

[0619]

[0620] for Film Composites - Method 2

[0621] To a glass jar with a screw top lid was added Ultem 1000 powder previously dried in a vacuum oven at 110 °C overnight (18 g), DMF (65.1 mL), and anhydrous dioxane (19.9 mL). The jar was capped and placed on rollers until a homogenous solution was obtained. The solution was stood upright and allowed to degas for at least 24 hours and stored in a desiccator until use. This provided a dope that is 18% Ultem, 61.5% NMP, and 20.5% dioxane by weight.

[0622]

[0623] for Film Composites - Method 3

[0624] To a glass jar with a screw top lid was added Ultem 1000 powder previously dried in a vacuum oven at 110 °C overnight (30 g), DMSO (51.8 mL), anhydrous dioxane (55.3 mL), and ethanol (7.6 mL). The jar was capped and placed on rollers until a homogenous solution was obtained. The solution was stood upright and allowed to degas for at least 24 hours and stored in a desiccator until use. This provided a dope that is 20% Ultem, 38% DMSO, 38% dioxane, and 4% ethanol by weight.

[0625]

[0626] for Film Composites - Method 4

[0627] To a glass jar with a screw top lid was added Ultem 1000 powder previously dried in a vacuum oven at 110 °C overnight (30 g), DMSO (54.5 mL), and anhydrous dioxane (58.2 mL). The jar was capped and placed on rollers until a homogenous solution was obtained. The solution was stood upright and allowed to degas for at least 24 hours and stored in a desiccator until use. This provided a dope that is 20% Ultem, 40% DMSO, and 40% dioxane.

[0628] Example 18: Membrane Support Fabrication for Film Composites - Method 1

[0629] An A4 sized piece of non woven fabric (Novatexx 2471, PP / PE) was taped to an appropriately sized piece of glass with polyimide tape. The glass was then clamped to an automated casting table (Elcometer 4340) and a casting blade with a blade height of 10 mil (254 pm) was placed at the top of the nonwoven sheet. Polymer dope solution (20 mF) was poured onto the nonwoven sheet in front of the casting blade and then casted at a rate of

[0630] 4.2 m / min. After 10 seconds, the nascent membrane was immersed in a coagulation bath of deionized water to induce phase separation and left in water for 24 hours for solvent exchange. The membrane was then placed in isopropanol for 24 hours for further solvent exchange, after which it was placed in a 1% w / v solution of 1, 3 -propanediamine in methanol for 24 hours to cross-link the membrane. After the completion of the cross-linking reaction the membrane was soaked in fresh isopropanol three times for 30 minutes each, followed by fresh hexanes three times for 30 minutes each. The membrane was then air dried and stored until use.

[0631] Example 19: Membrane Support Fabrication - Method 2

[0632] An A4 sized piece of non woven fabric (Novatexx 2471, PP / PE) was taped to an appropriately sized piece of glass with polyimide tape. The glass was then clamped to an automated casting table (Elcometer 4340) and a casting blade with a blade height of 10 mil (254 pm) was placed at the top of the nonwoven sheet. Polymer dope solution (20 mL) was poured onto the nonwoven sheet in front of the casting blade and then casted at a rate of

[0633] 4.2 m / min. After 10 seconds, the nascent membrane was immersed in a coagulation bath of deionized water to induce phase separation and left in water for 24 hours for solvent exchange. The membrane was then placed in isopropanol for 24 hours for further solvent exchange, after which it was placed in a 1% w / v solution of 1, 3 -propanediamine in methanol for 24 hours to cross-link the membrane, followed by a 5% w / v solution of 1, 3 -propanediamine for 24 hours. After the completion of the cross-linking reaction the membrane was soaked in fresh isopropanol three times for 30 minutes each, followed by fresh hexanes three times for 30 minutes each. The membrane was then air dried and stored until use.

[0634] Example 20: General Procedure for Polymer Cross-Linking for Membrane Support Fabrication Following solvent exchange in isopropanol, the polymer membrane of the membrane supports are cross-linked by placing in a 1% w / v solution of 1,3-diaminopropane in either ethanol or isopropanol for 4-24 h to cross-link the membrane. The resulting cross-linked membrane supports are air dried and stored for later use.

[0635] Example 21: General Procedure for Thin Film Composite (TFC) Fabrication

[0636] A membrane support prepared by the procedure of Example 20 is taped to a glass plate and clamped to a casting table (e.g., Elcometer 4340). A polymer solution, having a concentration from about 15 mg / mL to about 45 mg / mL, in a solvent (e.g., chloroform, THF, 2-Me-THF, 1,3-dioxolane, diethyl ketone, or toluene) is poured onto the membrane substrate and coated with a Mayer rod (1 mil, 25.4 μm) at a speed of about 4.2 m / min. One or more additional polymer layers may be subsequently added by the same method. The membrane is annealed in a chloroform vapor for about 5 min to solvent anneal the nascent film. The resulting membrane composite is air dried (e.g., from about 5 min to about 16 h at ambient temperature), followed by drying at 60 °C (e.g., from about 6 h to about 16 h). Exemplary TFCs prepared by these methods ranged in size from about 4 in x 6 in to about 6 in x 12 in. Examples 14-16 provide exemplary TFC fabrication methods.

[0637] Example 22: TFC Fabrication- Method 1

[0638] A 4” x 6” piece of Ultem membrane support was taped to a glass plate with heat resistant polyimide tape and clamped to a casting table (Elcometer 4340). A 1 wt% polymer solution in chloroform cooled to 4 °C (0.5 mL, 15 mg / mL) was poured onto the membrane substrate and coated with a Mayer rod (1 mil, 25.4 μm) at a speed of 4.2 m / min. The membrane was allowed to air dry for 15 min. Then a 3 wt% polymer solution in chloroform cooled to 4 °C (0.5 mL, 45 mg / mL) was poured onto the membrane substrate and coated with a Mayer rod (1 mil, 25.4 μm) at a speed of 4.2 m / min. The membrane was then placed into a glass chamber saturated with chloroform vapor for 5 minutes to solvent anneal the nascent film. The membrane composite was then covered and air dried for 48 hours, followed by drying at 50°C for 24 hours.

[0639] Example 23: TFC Fabrication- Method 2

[0640] A 4” x 6” piece of Ultem membrane support was taped to a glass plate with heat resistant polyimide tape and clamped to a casting table (Elcometer 4340). A 2.5 wt% polymer solution in chloroform cooled to 4 °C (0.5 mL, 15 mg / mL) was poured onto the membrane substrate and coated with a Mayer rod (1 mil, 25.4 μm) at a speed of 4.2 m / min. The membrane was then placed into a glass chamber saturated with chloroform vapor for 5 minutes to solvent anneal the nascent film. The membrane composite was then covered and air dried for 16 hours, followed by drying at 60°C for 6 hours.

[0641] Example 24: TFC Fabrication- Method 3

[0642] A 4” x 6” piece of Ultem membrane support was taped to a glass plate with heat resistant polyimide tape and clamped to a casting table (Elcometer 4340). A 2.5 wt% polymer solution in chloroform cooled to 4 °C (0.5 mL, 15 mg / mL) was poured onto the membrane substrate and coated with a Mayer rod (1 mil, 25.4 μm) at a speed of 4.2 m / min. The membrane was then placed into a glass chamber saturated with chloroform vapor for 5 minutes to solvent anneal the nascent film. The membrane composite was then covered and air dried for 16 hours, followed by drying at 60°C for 6 hours.

[0643]

[0644] In a 4L glass jar with a screw top lid, 48-55 wt% NMP and 9-12 wt% PEG400 were combined and stirred at ~500 rpm. To this jar, 35-40 wt% PEI (poly etherimide, e.g. Ultem 1000) was added, and the stirring was increased to 1000 rpm. After approximately one hour, once the solution was viscous and the jar was hot, the stirring was increased to about 1500 rpm.

[0645]

[0646] Example 26: Degassing of Support Dope for Composite HFMs

[0647] The glass jar in which the support dope was prepared (see Example 25) was sealed with paraffin around the cap. The jar was then placed in a metal container or aluminum tray, and heated in the oven at about 60 °C until the dope was clear and no more bubbles were visible.

[0648] Example 27: Spinning of Substrate for Composite HFMs

[0649] The apparatus used for spinning the substrate is shown in FIG. 2. As will be appreciated by one of ordinary skill in the art, any suitable apparatus for spinning the substrate may be used. The washing tank on the spinning apparatus was filled with deionized water. The degassed dope from Example 18 was poured into the dope tank, which was then secured with a C clamp. If required, the dope was heated to 60 °C for additional degassing. A clean spinneret was installed in the spinneret housing, and was connected to the bore fluid line and the dope line. The dope tank temperature was increased to 70 °C for spinning, and the spinneret block was heated to 90 °C. The bore fluid tank was filled with 1 L of NMP / water bore fluid. The bore fluid tank and dope tank valves were switched to the upstream position to their respective pumps. The take up bath heater was set to 50 °C. Rollers A, B, and C were set to 35, 36, and 37 rpm, respectively. The bore fluid pump was turned on and set to 30 rpm. Once the spinneret line was producing a steady stream of bore fluid without bubbles (the speed of flow can be temporarily increased to clear any bubbles), the dope pump was turned on and set to 15 rpm. The HF coming out of the spinneret was strung onto each roller without breaking it, and it was further strung on the tension controller, followed by the bobbin. The dope flow, bore fluid composition, bore fluid speed, spinneret air gap, roller speed, and tension control were adjusted as needed.

[0650] Spinning Parameters:

[0651] • Air Gap (in): 1 to 10

[0652] • Dope Flow (RPM): 20 -55

[0653] • Bore Flow (RPM): 10-35

[0654] • Bore Composition (NMP / H20)%: 0 / 100% - 85 / 15%

[0655] • Dope Tank Temperature ( C): 60-90

[0656] • Spinneret Temp (C): 70 - 90 • Coagulation Bath Temperature (C): 25 – 60

[0657] • Extraction Bath Temperature (C): 25-90

[0658] • Take-up Bath Temperature (C): 25-60

[0659] • Spinning Speed (RPM): 20 – 100

[0660] Example 28: Procedure for Washing and Cross-Linking Spun Substrate for Composite HFMS Following the spinning described in Example 27, the substrate was washed with solvent and crosslinked by subsequent washing in hot water, isopropanol, and hexane. The substrate was then dried, and subsequently washed with methanol, hot water, isopropanol, and then hexane. The substrate was then dried again before coating (see Example 29).

[0661] Example 29: Procedure for Coating Substrate for Composite HFMs

[0662] The apparatus used for coating the substrate is shown in FIG. 3. As will be appreciated by one of ordinary skill in the art, any suitable apparatus for coating the substrate may be used. The crosslinked substrate was first strung up and dried in the drying tower. The fiber was then coated with the coating solution in beaker 1. Next, the fiber was dried in coating tower 1, and then coated with the coating solution in beaker 2. Finally, the coated fiber was dried in coating tower 2, and collected in the take-up winder.

[0663] Coating Solution concentration:

[0664] • Selective polymer Solution: 0.1 w% to 3 w%

[0665] • Overcoating solution: 0.1 w% to 1.5w%

[0666]

[0667] Experiments were performed on a constant-volume variable pressure apparatus at 35 °C and 15 psi upstream pressure. The thin-film composite membranes were masked with epoxy on a brass support and degassed under high vacuum at 35°C for 1 h. The permeance, P, of gasses were determined using the following equation:

[0668]

[0669] where VDis the downstream volume, p2is the upstream pressure, p is the average downstream pressure calculated in the time interval considered, A is the exposed area of the membrane, and are the change in downstream pressure at steady-state permeation and

[0670]

[0671] when the system is sealed, respectively. Ideal gas pair selectivity for gases A and B (A / B) are defined to beA / p, where PAand PBare the permeances of gases A and B, respectively.

[0672] Example 31: Permeability Testing of Selected Composite Film Membranes

[0673] The gas permeability (Pgas, given in Barrer) for H2, CO2, CH4, N2, O2, and He was tested for a selection of exemplary monolithic “thick” film membranes (prepared according to methods of Example 5). Single-gas permeability experiments were performed at pressures from about 1 bar to about 50 bar and temperatures from about 20 °C to about 60 °C. The selectivity values given in Table S3 were calculated as the quotient of the permeability of the membrane for a first gas divided by the permeability of the membrane for a second gas, e.g. the selectivity for helium over nitrogen (He / N₂) under given conditions is equal to the value of P_He / P_N2, where Pm and PN2 are the experimentally determined single-gas permeability values under the given conditions.

[0674] The membranes tested were derived from the precursors below according to Examples 9- 11. Structures of the membranes tested are described in Table SI:

[0675] Table SI. Structures of Membranes Tested in Permeance / Permeability Experiments

[0676]

[0677]

[0678]

[0679] The single-gas permeability data for each tested membrane is given in table S2 below.

[0680] Table S2. Single-Gas Permeability Data for Representative Membranes

[0681]

[0682]

[0683]

[0684] Key for Table S2

[0685]

[0686] Using the single-gas permeability data of Table S2, the selectivities for each membrane were calculated and are shown in Table S3, below.

[0687] Table S3. Selectivities for Representative Membranes

[0688]

[0689]

[0690]

[0691] Key for Table S3

[0692]

[0693] The teachings of all patents, published applications and references cited herein are incorporated by reference in their entirety. While this invention has been particularly shown and described with references to example embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention encompassed by the appended claims.

Claims

CLAIMSWhat is claimed is:

1. A process for isolation of He, comprisinga) contacting a first gas separation membrane with a first gas stream comprising He and H₂, thereby producing a second gas stream comprising He and H₂;b) contacting the second gas stream with air under conditions sufficient to combust the H₂, thereby producing a third gas stream comprising He; andc) contacting a second gas separation membrane with the third gas stream, thereby producing a fourth gas stream comprising He.

2. The process of claim 1, further comprising pressurizing the third gas stream prior to contacting with the second gas separation membrane.

3. The process of claim 2, whereincombusting the H₂ comprises releasing energy, andpressurizing the third gas stream comprises consuming the energy.

4. The process of any one of claims 1-3, wherein the first gas stream comprises about 0.1 vol. % to about 50 vol. % He.

5. The process of any one of claims 1-4, wherein the first gas stream comprises about 0.1 vol. % to about 30 vol. % He.

6. The process of any one of claims 1-5, wherein the first gas stream comprises about 0.5 vol. % to about 10 vol. % He.

7. The process of any one of claims 1-6, wherein the first gas stream comprises about 0.8 vol. % to about 3.9 vol. % He.

8. The process of any one of claims 1-7, wherein the first gas stream comprises about 1 vol. % to about 70 vol. % H2.

9. The process of any one of claims 1-8, wherein the first gas stream comprises about 2 vol. % to about 50 vol. % H2.

10. The process of any one of claims 1-9, wherein the fourth gas stream comprises about 5 vol. % to about 27 vol. % H2.

11. The process of any one of claims 1-10, wherein the fourth gas stream comprises about 50 vol. % to about 100 vol. % He.

12. The process of any one of claims 1-11, wherein the fourth gas stream comprises about 75 vol. % to about 100 vol. % He.

13. The process of any one of claims 1-12, wherein the fourth gas stream comprises about 80 vol. % to about 99 vol. % He.

14. The process of any one of claims 1-13, wherein the fourth gas stream comprises about 95 vol. % to about 99 vol. % He.

15. The process of any one of claims 1-14, wherein the first gas stream contacts the first gas separation membrane at a pressure about 70 bar to about 200 bar.

16. The process of any one of claims 1-15, wherein the first gas stream contacts the first gas separation membrane at a pressure about 100 bar to 140 bar.

17. The process of any one of claims 1-16, wherein the first gas stream contacts the first gas separation membrane at a temperature about 25 °C to about 50 °C.

18. The process of any one of claims 1-17, wherein the first gas stream contacts the first gas separation membrane at a temperature about 35 °C.

19. The process of any one of claims 1-18, wherein the third gas stream contacts the second gas separation membrane at a pressure about 70 bar to about 200 bar.

20. The process of any one of claims 1-19, wherein the third gas stream contacts the second gas separation membrane at a pressure about 100 bar to 140 bar.

21. The process of any one of claims 1-20, wherein the third gas stream contacts the second gas separation membrane at a temperature about 25 °C to about 50 °C.

22. The process of any one of claims 1-21, wherein the third gas stream contacts the second separation membrane at a temperature about 35 °C.

23. The process of any one of claims 1-22, wherein the first gas separation membrane is a hollow fiber membrane comprising a plurality of polymer chains.

24. The process of any one of claims 1-23, wherein the second gas separation membrane is a hollow fiber membrane comprising a plurality of polymer chains.

25. The process of any one of claims 1-22, wherein the first gas separation membrane is a composite membrane comprising:a mesoporous membrane support layer comprising a plurality of pores extending through the support layer, said support layer having a first side, a second side, and a thickness; andoptionally, a gutter layer comprising a permeable elastic polymer, said gutter layer having a first side, a second side, and a thickness;a thin film membrane selective layer comprising a plurality polymer chains, said selective layer having a first side, a second side, and a thickness;wherein:when the gutter layer is present, the second side of the support layer is disposed along the first side of the gutter layer, and the second side of the gutter layer is disposed along the first side of the selective layer;when the gutter layer is absent, the second side of the support layer is disposed along the first side of the selective layer; andthe thickness of the selective layer is less than about 10 microns.

26. The process of any one of claims 1-23, wherein the second gas separation membrane is a composite membrane comprising:a mesoporous membrane support layer comprising a plurality of pores extending through the support layer, said support layer having a first side, a second side, and a thickness; andoptionally, a gutter layer comprising a permeable elastic polymer, said gutter layer having a first side, a second side, and a thickness;a thin film membrane selective layer comprising a plurality polymer chains, said selective layer having a first side, a second side, and a thickness;wherein:when the gutter layer is present, the second side of the support layer is disposed along the first side of the gutter layer, and the second side of the gutter layer is disposed along the first side of the selective layer;when the gutter layer is absent, the second side of the support layer is disposed along the first side of the selective layer; andthe thickness of the selective layer is less than about 10 microns.

27. The process of any one of claims 1-22, wherein the first gas separation membrane is a composite membrane comprising:a mesoporous membrane support layer comprising a plurality of pores extending through the support layer, said support layer having a first side, a second side, and a thickness; andoptionally, a gutter layer comprising a permeable elastic polymer, said gutter layer having a first side, a second side, and a thickness;a thin film membrane selective layer comprising a plurality of polymer chains, said selective layer having a first side, a second side, and a thickness;wherein:the composite membrane is in the form of a hollow fiber;when the gutter layer is present, the second side of the support layer is disposed along the first side of the gutter layer, and the second side of the gutter layer is disposed along the first side of the selective layer;when the gutter layer is absent, the second side of the support layer is disposed along the first side of the selective layer; andthe thickness of the selective layer is less than about 10 microns.

28. The process of any one of claims 1-23, wherein the second gas separation membrane is a composite membrane comprising:a mesoporous membrane support layer comprising a plurality of pores extending through the support layer, said support layer having a first side, a second side, and a thickness; andoptionally, a gutter layer comprising a permeable elastic polymer, said gutter layer having a first side, a second side, and a thickness;a thin film membrane selective layer comprising a plurality of polymer chains, said selective layer having a first side, a second side, and a thickness;wherein:the composite membrane is in the form of a hollow fiber;when the gutter layer is present, the second side of the support layer is disposed along the first side of the gutter layer, and the second side of the gutter layer is disposed along the first side of the selective layer;when the gutter layer is absent, the second side of the support layer is disposed along the first side of the selective layer; andthe thickness of the selective layer is less than about 10 microns.

29. The process of any one of claims 23-28, wherein the plurality of polymer chains comprises at least one unit of Formula lb:(lb);wherein:each R3is, independently at each occurrence, selected from C1-C4 alkyl, C1-C4 fluoroalkyl, halo, optionally substituted amino, and hydroxy;each R4and R5is, independently at each occurrence, selected from H, C1-C4 alkyl, C1-C4 fluoroalkyl, halo, optionally substituted amino, and hydroxy;A is, independently at each occurrence, selected from NRD, O, S, CRERF, S=O, and C=O; when present, B is, independently at each occurrence, selected from NRD, O, S, CRERF, and C=O;wherein, when B is present, at least one of A and B is CRERFor C=O;RDis, independently at each occurrence, selected from H, alkyl, -O-alkyl, or haloalkyl;REand RFare, independently at each occurrence, selected from H, OH, SH, halo, amine, alkyl, - (H)C=O, -O-alkyl, and haloalkyl;or REand RF, together with the atom to which they are attached, form a cycloalkyl, cycloalkenyl, heterocycloalkenyl, or heterocycloalkyl, which is optionally substituted with one or more RH, wherein RHis selected from H, alkyl, alkoxy, and hydroxy;optionally wherein REand RF, together with the atoms to which they are attached, form a groupselected fromn is 0 or 1;each o is, independently at each occurrence, 0, 1, 2, or 3;— represents an optional bond;C is, independently at each occurrence, selected from:; wherein each * represents a point of attachment to the unit of Formula lb; andD is, independently at each occurrence, a bond or selected from O, C=O, SO2, CR4R4, phenylene,30. The process of claim 29, wherein at least one unit of Formula lb is a unit of Formula Ic:(Ic).

31. The process of claim 29, wherein at least one unit of Formula lb is:

32. The process of any one of claims 29-31, wherein the plurality of polymer chains comprises at least one unit of Formula V:(V);wherein:R1and R2are independently selected from hydride group, alkyl groups, aryl groups, heterocyclic groups, halogen groups, groups including a — O — moiety, groups including a — O(CO) — moiety, groups including a — O(CO)O — moiety, groups including a O(CO)N< moiety, groups including a — S — moiety, groups including a — B< moiety, — NO2, groups including a — N< moiety, groups including a — P< moiety, groups including a — (PO)< moiety, — CHO, groups including a — (CO) — moiety, groups including a — (CO)O — moiety, and groups including a — (CO)N< moiety;X1is selected from — [O]—, — [S]—, — [B(O)Ra]—, — [NRa]—, — [P(O)Ra]—, —[(PO)(O)Ra]—, —[CO]—, — [CRaRb]—, — [C(O)Ra(O)Rb]—, and— [Si(O)Ra(O)Rb]—, and Raand Rbare independently selected from hydride group, alkyl groups, aryl groups, and heterocyclic groups; andM is selected from aromatic groups and heterocyclic groups.

33. The process of claim 32, wherein the plurality of polymer chains comprises at least one unit of Formula Va:(Va);wherein:each R3is, independently at each occurrence, selected from C1-C4 alkyl, C1-C4 fluoroalkyl, halo, optionally substituted amino, and hydroxy;each R4and R5is, independently at each occurrence, selected from H, C1-C4 alkyl, C1-C4 fluoroalkyl, halo, optionally substituted amino, and hydroxy;each o is, independently at each occurrence, 0, 1, 2, or 3;C is, independently at each occurrence, selected from:represents a point of attachment to the unit of Formula Va; andD is, independently at each occurrence, a bond or selected from O, C=O, SO2, CR4R4, phenylene,34. The process of claim 33, wherein the at least one unit of Formula Va is a unit of Formula Vb:

35. The process of any one of claims 23-28, wherein the plurality of polymer chains comprises a copolymer comprising:at least one first unit comprising:a subunit of Formula I*:(I*); anda subunit of any one of Formula II*, III*, IV-a*, or IV-b*:(IV-a*); orand at least one second unit comprising:a subunit of Formula I*:a subunit of any one of Formula V* and VI*:(VI*);wherein:A is, independently at each occurrence, selected from:the unit of Formula I*; andFAis, independently at each occurrence, selected from a bond, O, S, C=O, SO2,represents a point of attachment to FA;FBis, independently at each occurrence, selected from, wherein each ** represents a point of attachment to the adjacent phenylene rings of A;each RAand RBis, independently at each occurrence, selected from H, halo, hydroxyl, C1-C4 alkyl, C1-C4 haloalkyl, and aryl; wherein each is optionally substituted;wherein one instance of ' / w\rof Formula I* in the first unit represents a connection point to any one of Formula II*, III*, IV-a* or IV-b* and the otherjwv' of Formula I the represents a connection point to the rest of the polymer; wherein one instance of * / vw' of Formula I* in the second unit represents a connection point to any one of Formula V* or VI*, and the other » A / V' of Formula I* represents a connection point to the rest of the polymer;B is, independently at each occurrence, -[(CH2)2O]p-[O(CH2)2]q-[O(CH2)2]r-, -[(CH2)3O]p-[O(CH2)3]q-[(CH2)3O]r-, -[(CH2)]PCH(COOH)-, -Si(CH3)2- [OSi(CH3)2]r, or -OSi(CH3)2[(CH2)]q-; wherein:each p is, independently at each occurrence, an integer from 0 to about 10; each q is, independently at each occurrence, an integer from 0 to about 10; and each r is, independently at each occurrence, an integer from 0 to about 10; each R1is, independently at each occurrence, selected from halo, hydroxyl, alkyl, haloalkyl, acetyl, acetoxy, acyloxy, and carboxyl; wherein each is optionally substituted;each m is, independently at each occurrence, 0, 1, 2, 3, or 4;CAis, independently at each occurrence, selected from a bond, O, C=O, NHC(=O),of attachment to adjacent phenylene rings of IV-b*;each Rcis, independently at each occurrence, selected from H, halo, hydroxyl, C1-C4 alkyl, C1-C4 haloalkyl, and aryl, wherein each is optionally substituted;wherein one instance of ' / w' inFormula II*, III*, IV-a* or IV-b* in the first unit represents a connection point to Formula I* and the other instance of * / vw' in Formula II*, III*, IV- a* or IV-b* represents a connection point to the rest of the polymer;D is, independently at each occurrence, selected from NRD, O, S, CRERF, SO, and C=O; when present, E is, independently at each occurrence, selected from NRD, O, S, CRERF, and C=O;wherein, when E is present, at least one of D and E is CRERFor C=O;RDis, independently at each occurrence, selected from H, alkyl, -O-alkyl, or haloalkyl;REand RFare, independently at each occurrence, selected from H, OH, SH, halo, amine, alkyl, -C(=O)H, -O-alkyl, and haloalkyl;or REand RF, together with the atom to which they are attached, form a cycloalkyl, cycloalkenyl, heterocycloalkenyl, or heterocycloalkyl, which is optionally substituted with one or more RH, wherein RHis selected from H, alkyl, alkoxy, and hydroxy;optionally wherein REand RF, together with the atoms to which they are attached,form a group selected fromn is 0 or 1;— represents an optional bond;R2is, independently at each occurrence, selected from halo, C1-C4 alkyl, C1-C4 haloalkyl, C1-C4 haloalkoxyl, carboxyl, optionally substituted amino, and hydroxy; each o is, independently at each occurrence, 0, 1, 2, or 3; andwherein one instance of cwv* in Formula V* or VI* represents a connection point to Formula I* and the other instance of ' / vv\ inFormula V* or VI* represents a connection point to the rest of the polymer.

36. The process of claim 35, wherein:wherein each * represents a point of attachment to the unit of Formula I*; andFAis, independently at each occurrence, selected from a bond, O, S, C=O, SO2, NRACRARA, SiRARA, phenylene,FBis, independently at each occurrence, selected fromwherein each ** represents a point of attachment to adjacent phenyl rings of A; andRAis, independently at each occurrence, selected from H, C1-C4 alkyl, C1-C4 fluoroalkyl, and aryl.

37. The process of claim 35 or 36, wherein the subunit of Formula I* is selected from:

38. The process of any one of claims 35-37, wherein the at least one first unit comprises: the subunit of Formula I* and the subunit of Formula II*.

39. The process of claim 38, wherein B is, independently at each occurrence, - CH2CH(COOH)- or -Si(CH3)2-[OSi(CH3)2]rOSi(CH3)2(CH2)3-.

40. The process of any one of claims 35-39, wherein the subunit of Formula II* is selected41. The process of any one of claims 35-37, wherein the at least one first unit comprises: the subunit of Formula I* and the subunit of Formula III*.

42. The process of claim 41, wherein each R1is, independently at each occurrence, selected from halo, hydroxyl, C1-C4 alkyl, C1-C4 fluoroalkyl, acetyl, acyloxy, and carboxyl; wherein each alkyl, fluoroalkyl, acetyl, acyloxy, or carboxyl is optionally substituted with amino, hydroxy, or amino and hydroxy.

43. The process of any one of claims 35-42, wherein the subunit of Formula III* is selected44. The process of any one of claims 35-37, wherein the at least one first unit comprises: the subunit of Formula I* and the subunit of Formula IV-a*.

45. The process of claim 44, wherein the subunit of Formula IV-a* is selected from:

46. The process of any one of claims 35-37, wherein the at least one first unit comprises: the subunit of Formula I and the subunit of Formula IV-b*.

47. The process of claim 46, wherein the subunit of Formula IV-b* is selected from:

48. The process of any one of claims 35-47, wherein the at least one second unit comprises: the subunit of Formula I and the subunit of Formula V*.

49. The process of claim 48, wherein the subunit of Formula V* is selected from:

50. The process of any one of claims 35-47, wherein the at least one second unit comprises: the subunit of Formula I* and the subunit of Formula VI*.

51. The process of claim 50, wherein the subunit of Formula VI* is selected from:

52. The process of any one of claims 35-51, wherein the first unit has the structure of Formula la*, lb*, or Ic*:(Ic*).

53. The process of claim 52, wherein the first unit has the structure of Formula la-1*, Ib-l* or Ic-1*:(Ic-1*).

54. The process of claim 53, wherein RAis fluoroalkyl.

55. The process of claim 54, wherein RAis CF3.

56. The process of any one of claims 35-55, wherein the second unit has the structure of Formula IIa* or IIb*:(IIb*).

57. The process of claim 56, wherein the second unit has the structure of Formula IIa-1* or IIb-1*:(IIa-1*); or(IIb-1*).

58. The process of claim 57, wherein RAis fluoroalkyl.

59. The process of claim 58, wherein RAis CF3.

60. The process of any one of any one of claims 25-59, wherein the gutter layer is present.

61. The process of claim 60, wherein the gutter layer comprises poly siloxane.

62. The process of any one of claims 25-61, wherein the support layer comprises a polymer selected from polyethylenimine, polyether ether ketone, poly vinylidene difluoride, polyvinylfluoride, polytetrafluoroethylene, poly(acrylonitrile), polysulfone, cellulose acetate, poly ether sulfone, and polyimide.