WO2017148850A1

WO2017148850A1 - Method for the preparation of a membrane which comprises an organic polymer of intrinsic microporosity (pim) and a sulfonated polyarylenesulfone polymer

Info

Publication number: WO2017148850A1
Application number: PCT/EP2017/054479
Authority: WO
Inventors: Martin Weber; Claudia Staudt; Christian Maletzko; Wai Fen YONG; Tai-Shung Chung
Original assignee: Basf Se; National University Of Singapore
Priority date: 2016-02-29
Filing date: 2017-02-27
Publication date: 2017-09-08

Abstract

The present invention relates to a method for the preparation of a membrane (M) which comprises an organic polymer of intrinsic microporosity (PIM) and a sulfonated polyarylenesulfone polymer (sP). The present invention further relates to the membrane (M) obtained by said method and the use of this membrane (M) for the separation of gases from gas mixtures.

Description

METHOD FOR THE PREPARATION OF A MEMBRANE WHICH COMPRISES AN ORGANIC POLYMER OF INTRINSIC MICROPOROSITY (PIM) AND A SULFONATED POLYARYLENESULFONE POLYMER

Description

Membrane materials are classified into two broad groups, polymeric materials and non- polymeric materials. Polymeric membranes have been widely used for gas separation because of their relatively low costs and easy processing into hollow fibre membranes for industrial applications. On the other hand, non-polymeric membranes such as nanoparticles, metal organic frame works, carbon nanotubes, zeolites and others tend to have better thermal and chemical stability and higher selectivity for gas separation. Nevertheless, their drawbacks of mechanical brittleness, considerable costs, difficulties in pore-size control and formation of defect-free layer may render them to be less commercially attractive.

"Polymers of intrinsic microporosity (PIM)" are a new generation of polymer materials for membranes and combine some of the advantageous properties of a microporous non-polymeric material, such as the selective take-up and transport of molecular species, with the good solution processability of a polymer. Due to their highly rigid and contorted molecular structures, polymers of intrinsic microporosity (PIM) usually exhibit a high gas permeability combined with a moderate gas selectivity. Polymers of intrinsic microporosity (PIM) are described in "Polymers of Intrinsic Microporosity" (doi:10.5402/2012/513986).

The object of the present invention therefore was to provide a method for preparing a membrane (M) formed of an organic polymer of intrinsic microporosity (PIM), which exhibits an increased selectivity without significantly reducing the high permeability. The method should be easy to perform at relatively low costs. Membranes (M), obtained by the method, should exhibit low polymer polydispersity as well as good mechanical properties, particularly with regard to applications as gas-selective membranes.

This object is achieved by a method for the preparation of a membrane (M) which comprises an organic polymer of intrinsic microporosity (PIM) and a sulfonated polyarylenesulfone polymer (sP), wherein the process comprises the steps: i) providing a solution (S) which comprises the organic polymer of intrinsic microporosity (PIM), the sulfonated polyarylenesulfone polymer (sP) and at least one solvent,

ii) separating the at least one solvent from the solution (S) to obtain the membrane (M).

It has surprisingly been found that the use of membranes (M) comprising organic polymers of intrinsic microporosity (PIM) and a sulfonated polyarylenesulfone polymer (sP) for the separation of gases from gas mixtures leads to an improved absorption selectivity toward specific gases. The presence even of only small amounts of a sulfonated polyarylenesulfone polymer (sP) in the membrane (M) leads to a noticeable improvement of the selectivity.

By the inventive method, the membrane (M) can be impacted with the properties of sulfonic acid groups. The inventive method does not require complicated and cost intensive synthetic procedures and is thus, very economic. The membrane (M) is easy to process and shows good flexibility and sturdiness properties during handling.

Moreover, it has also surprisingly been found that the membrane (M) can be produced from a solution (S) which comprises the sulfonated polyarylenesulfone polymer (sP), the organic polymer of intrinsic microporosity (PIM) and the at least one solvent. By the inventive process, the dissolution of the sulfonated polyarylenesulfone polymer (sP) and the organic polymer of intrinsic microporosity (PIM) can be improved. This minimizes the degree of agglomeration of polymer chains during the preparation of the membrane (M).

It shall be assumed that the above-mentioned advantages are achieved by the sulfonated polyarylenesulfone polymer (sP). It shall be assumed that the sulfonic acid groups (-S0₃H) provide the possibility of electrostatic interactions, hydrogen bonding interactions and the like. This enhances the absorption selectivity to polar gases like carbon dioxide (C0₂) in comparison with non-polar gases like nitrogen (N₂) or methane (CH₄). The aforementioned assumptions are not intended to limit the present invention.

The present invention will be described in more detail hereinafter.

Step i)

In step i), a solution (S) is provided which comprises an organic polymer of intrinsic microporosity (PIM), a sulfonated polyarylenesulfone polymer (sP) and at least one solvent. "An organic polymer of intrinsic microporosity (PIM)" within the context of the present invention means precisely one organic polymer of intrinsic microporosity (PIM) and also a mixture of two or more organic polymers of intrinsic microporosity (PIM). The same holds true for "a sulfonated polyarylenesulfone polymer (sP)". "A sulfonated polyarylenesulfone polymer (sP)" within the context of the present invention means precisely one sulfonated polyarylenesulfone polymer (sP) and also a mixture of two or more sulfonated polyarylenesulfone polymers (sP).

"At least one solvent" means precisely one solvent and also a mixture of two or more solvents.

The solution (S) can be provided in step i) by any method known to the skilled person. For example, the solution (S) can be provided in step i) in customary vessels which may comprise a stirring device and preferably a temperature control device.

Preferably, the solution (S) is provided by dissolving the sulfonated polyarylenesulfone polymer (sP) and the organic polymer of intrinsic microporosity (PIM) in the at least one solvent. The dissolution of the sulfonated polyarylenesulfone polymer (sP) and the organic polymer of intrinsic microporosity (PIM) in the at least one solvent to provide the solution (S) is preferably affected under agitation. The dissolution of the sulfonated polyarylenesulfone polymer (sP) and the organic polymer of intrinsic microporosity (PIM) may be effected concurrently or in succession.

Step i) is preferably carried out at elevated temperatures, especially in the range from 20 to 120°C, preferably in the range from 40 to 100°C. A person skilled in the art will choose the temperature in accordance with the at least one solvent. The solution (S) preferably comprises the sulfonated polyarylenesulfone polymer (sP) and the organic polymer of intrinsic microporosity (PIM) completely dissolved in the at least one solvent. This means that the solution (S) preferably comprises no solid particles of the sulfonated polyarylenesulfone polymer (sP) and/or the organic polymer of intrinsic microporosity (PIM). Therefore, the sulfonated polyarylenesulfone polymer (sP) and the organic polymer of intrinsic microporosity (PIM) preferably cannot be separated from the at least one solvent by filtration.

The solution (S), for example, comprises from 0.001 to 4.0% by weight, preferably from 0.01 to 3.0% by weight of the sulfonated polyarylenesulfone polymer (sP), based on the sum of the percent by weight of the sulfonated polyarylenesulfone polymer (sP), the organic polymer of intrinsic microporosity (PIM) and the at least one solvent, preferably based on the total weight of the solution (S). The solution (S), for example, comprises from 0.099 to 19.8% by weight, preferably from 0.297 to 17.00% by weight of the organic polymer of intrinsic microporosity (PIM), based on the sum of the percent by weight of the sulfonated polyarylenesulfone 5 polymer (sP), the organic polymer of intrinsic microporosity (PIM) and the at least one solvent, preferably based on the total weight of the solution (S).

The total amount of the sulfonated polyarylenesulfone (sP) and the organic polymer of intrinsic microporosity (PIM) in the solution (S) preferably is 0.1 to 20% by weight, more 10 preferably 0.3 to 15% by weight and especially 0.5 to 10% by weight, based on the total weight of the solution (S).

The present invention accordingly also provides a method wherein the total amount of the organic polymer of intrinsic microporosity (PIM) and the sulfonated 15 polyarylenesulfone polymer (sP) in the solution (S) is 0.1 to 20% by weight, based on the total weight of the solution (S).

The percent by weight of the sulfonated polyarylenesulfone polymer (sP), the organic polymer of intrinsic microporosity (PIM) and the at least one solvent generally add up to 20 100%.

Preferred solvents for providing the solution (S) in step (i) are N-methylpyrrolidone, dimethylacetamide, dimethyl sulfoxide, dimethylformamide, sulfolane (tetrahydro- thiophene-1 ,1 -dioxide), dichloromethane and chloroform. Dichloromethane and 25 chloroform are particularly preferable.

In a preferred embodiment, a solvent mixture of dichloromethane and chloroform is present in the solution (S). In principle, any ratio of chloroform to dichloromethane can be present in the solution (S). Preferably, the ratio of chloroform to dichloromethane in 30 the at least one solvent is 10 : 1 , more preferably 5 : 1 and especially 2 : 1 , based on the total weight of the at least one solvent present in the solution (S).

The present invention accordingly also provides a method wherein the at least one solvent is a solvent mixture comprising chloroform and dichloromethane.

35

The duration of step i) may vary between wide limits. The duration of step i) is preferably in the range from 10 minutes to 48 hours, especially in the range from 10 minutes to 24 hours and more preferably in the range from 15 minutes to 12 hours. A person skilled in the art will choose the duration of step i) so as to obtain a 40 homogeneous solution of the sulfonated polyarylenesulfone polymer (sP) and the organic polymer of intrinsic microporosity (PIM) according to the present invention in the at least one solvent. More detailed information regarding the sulfonated polyarylenesulfone polymer (sP) and the organic polymer of intrinsic microporosity (PIM) are given below. Sulfonated Polyarylenesulfone Polymer (sP)

Sulfonated polyarylenesulfone polymers (sP) are a class of polymers known to the person skilled in the art. In principle, it is possible to use any of the sulfonated polyarylenesulfone polymers (sP) that are known to the person skilled in the art and/or that can be produced by known methods. Appropriate methods for the preparation of sulfonated polyarylenesulfone polymers (sP) are explained at a later stage below. Preferred sulfonated polyarylenesulfone polymers (sP) comprise repeating units of the general formula I:

where t and q : are each independently 0, 1 , 2 or 3, Q, T and Y: are each independently a chemical bond or selected from

-S-, -S0₂- -S(=0)-, -C(=0)-, -N=N- and -CR^aR^b- wherein R^a and R^b are each independently a hydrogen atom or a CrC^-alkyl, d-C₁₂-alkoxy or C₆-C₁₈-aryl group, and wherein at least one of Q, T and Y is -S0₂-

Ar and Ar¹: are each independently C₆-C₁₈ aryl, wherein said C₆-C₁₈ aryl is unsubstituted or substituted with at least one substituent selected from C C₁₂ alkyl, C C₁₂ alkoxy, C₆-C₁₈ aryl, halogen and -S0₃X, p, m, n, and k: are each independently 0, 1 , 2, 3 or 4, with the proviso that the sum total of p, m, n and k is not less than 1 , and

X: is hydrogen or one cation equivalent.

The present invention accordingly also provides a method wherein the sulfonated polyarylenesulfone polymer (sP) has the general formula I:

where t and q : are each independently 0, 1 , 2 or 3,

Q, T and Y: are each independently a chemical bond or selected from -0-,

Ar and Ar¹ : are each independently C₆-C₁₈ aryl, wherein said C₆-C₁₈ aryl is unsubstituted or substituted with at least one substituent selected from C C₁₂ alkyl, C C₁₂ alkoxy, C₆-C₁₈ aryl, halogen and -S0₃X, p, m, n, and k: are each independently 0, 1 , 2, 3 or 4, with the proviso that the sum total of p, m, n and k is not less than 1 , and X: is hydrogen or one cation equivalent.

If Q, T, or Y, with the abovementioned preconditions, is a chemical bond, this means that the adjacent group on the left-hand side and the adjacent group on the right-hand side have direct linkage to one another by way of a chemical bond.

R^a and R^b are each independently hydrogen or C-|-C₁₂ alkyl.

Preferred C-|-C₁₂ alkyl groups include linear and branched, saturated alkyl groups of 1 to 12 carbon atoms. The following moieties are suitable in particular: C-|-C₆ alkyl, such as methyl, ethyl, n-propyl, i-propyl, n-butyl, sec-butyl, 2- or 3-methylpentyl or comparatively long-chain moieties such as unbranched heptyl, octyl, nonyl, decyl, undecyl, lauryl, and the branched analogs thereof.

Alkyl moieties in the C-|-C₁₂ alkoxy groups used include the above-defined alkyl groups of 1 to 12 carbon atoms. Preferably used cydoalkyi moieties include in particular C₃-C₁₂ cycloalkyl moieties, e.g., cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclopropylmethyl, cyclopropylethyl, cyclopropylpropyl, cyclobutylmethyl, cyclobutylethyl, cyclopentylethyl, -propyl, -butyl, -pentyl, -hexyl, -cyclohexylmethyl, -dimethyl, -trimethyl.

Ar and Ar¹ are each independently C₆-C₁₈ aryl. Proceeding from the starting materials hereinbelow, Ar preferably derives from an electron-rich aromatic substance very susceptible to electrophilic attack, preferably selected from the group consisting of sulfonated or unsulfonated hydroquinone, resorcinol, dihydroxynaphthalene, in particular 2,7-dihydroxynaphthalene and 4,4'-bisphenol. Ar¹ is preferably an unsubstituted C₆ or C₁₂ arylene group. Ar and Ar¹ in the preferred embodiment of formula (I) are each preferably selected independently from sulfonated or unsulfonated 1 ,4-phenylene, 1 ,3-phenylene, naphthylene, in particular 2,7-dihydroxynaphthalene and 4,4'-bisphenylene.

The membrane (M) of the present invention preferably comprises at least one sulfonated polyarylenesulfone polymer (sP) having the following structural units (la) to (lo):

01

"(X^eOS) Vos) '(x^eos) '(x^eos)

6/.^^S0 /.l0Zda/X3d 0S88H/Z.10Z OAV (Im)

(S0₃X)_p (S0₃X)_o (S0₃X), (SQ₃X)_m (S0₃X)_n (S0₃X)

where

I, k, m, n, o, p are each independently 0, 1 , 2, 3 or 4 subject to the proviso that the sum total of I, k, m, n, o and p is≥1 , and

X is hydrogen or one cation equivalent.

By "one cation equivalent" in the context of the present invention is meant one cation of a single positive charge or one charge equivalent of a cation with two or more positive charges, for example Li, Na, K, Mg, Ca, NH₄, preferably Na, K.

In addition to the preferred building blocks (la) to (lo), preference is also given to those structural units in which one or more sulfonated or unsulfonated 1 ,4-dihydroxyphenyl units are replaced by resorcinol or dihydroxynaphthalene.

Copolymers constructed of the various structural units in combination or of sulfonated and non-sulfonated structural units are also usable.

Structural units (la), (lb), (Ig) and (Ik) or copolymers thereof are used with particular preference as repeat unit of general formula (I).

In one particularly preferred embodiment, Ar is 1 ,4-phenylene, t is 1 , T is a chemical bond, Y is -S0₂- q is 0, p is 0, m is 0, n is 1 and k is 1 . Sulfonated polyphenylenesulfones constructed of this recited structural repeat unit are denoted sPPSU. In a particularly preferred embodiment, Ar is 1 ,4-phenylene, t is 0, Y is -S0₂- q is 0, n is 0 and k is 0. Polyarylenesulfones constructed of this recited structural repeat unit are denoted sulfonated polyether ether sulfones (sPEES).

In one advantageous embodiment, the sulfonated polyarylenesulfone polymer (sP) comprises a nonsulfonated re eat unit of formula (1 )

and a sulfonated repeat unit of formula (2)

In particular, the sulfonated polyarylenesulfone polymer (sP) consists exclusively of non-sulfonated repeating units of formula (1 ) and sulfonated repeat units of formula (2).

In a very advantageous embodiment, the sulfonated polyarylenesulfone polymer (sP) comprises a nonsulfonated repeat unit of formula (1 a)

and a sulfonated repeat unit of formula (2a)

(2a) In particular, the sulfonated polyarylenesulfone polymer (sP) consists exclusively of non-sulfonated repeat units of formula (1 a) and sulfonated repeating units of formula (2a).

The sulfonated polyarylenesulfone polymers (sP) used according to the present invention preferably have a viscosity number of 20 ml/g to 120 ml/g, preferably of 20 ml/g to 80 ml/g. This viscosity number is quantified according to DI N EN ISO 1628-1 in a 1 % solution of N-methylpyrrolidone (NMP) at 25°C.

The weight average molecular weight (M_w) of the sulfonated polyarylenesulfone polymer (sP) used in the method of the present invention is generally in the range from 10 000 to 200 000 g/mol, preferably in the range from 15 000 to 150 000 g/mol and more preferably in the range from 18 000 to 100 000 g/mol. The weight average molecular weights (M_w) are measured using gel permeation chromatography (GPC). Dimethylacetamide (DMAc) was used as solvent and narrowly distributed polymethyl methacrylate was used as standard in the measurement.

The sulfonated polyarylenesulfone polymer (sP) according to the invention is particularly preferably formed by converting a reaction mixture (R_s) comprising the components (A1 ), (A2), and (B) in aprotic polar solvents in the presence of anhydrous alkali metal carbonate, in particular sodium carbonate, potassium carbonate, calcium carbonate, or a mixture thereof, very particular preference being given here to potassium carbonate. A particularly suitable combination is N-methyl-2-pyrrolidone as solvent and potassium carbonate as base. Components (A1 ) and (A2) are reacted with component (B) in a polycondensation reaction.

The reaction mixture (R_s) is the mixture which is provided for forming the sulfonated polyarylenesulfone polymer (sP). All particulars herein in relation to the reaction mixture (R_s) thus relate to the mixture which is present before the polycondensation. The polycondensation takes place to convert reaction mixture (R_s) into the target product, the sulfonated polyarylenesulfone polymer (sP), by polycondensation of components (A1 ), (A2) and (B). The present invention accordingly also provides a method wherein the polyarylenesulfone polymer (sP) is obtained by converting a reaction mixture (R_s) comprising as components:

(A1 ) an aromatic dihalogensulfone component,

(A2) an aromatic dihalogensulfone component comprising at least one -S0₃X group, wherein X is hydrogen or a cation equivalent, (B) an aromatic dihydroxy component.

Component (A 1) Component (A1 ), which is also referred to as the aromatic dihalogensulfone component, is present in the reaction mixture (R_s) in the form of at least one aromatic dihalogensulfone component. What is meant herein by "at least one aromatic dihalogensulfone component" is precisely one aromatic dihalogensulfone component and also mixtures of two or more aromatic dihalogensulfone components.

In the context of the present invention, the person skilled in the art understands that component (A1 ) comprises preferably no -S0₃X groups.

Component (A1 ) generally is present in the reaction mixture (R_s) in an amount of at least 90 mol-%, based on the total molar amount of components (A1 ) and (A2) in the reaction mixture (R_s). Preferably, the reaction mixture (R_s) comprises at least 92 mol-% and more preferably at least 95 mol-% of component (A1 ), based on the total molar amount of components (A1 ) and (A2) in the reaction mixture (R_s). Likewise, the reaction mixture (R_s) comprises not more than 99.5 mol-% of component (A1 ), based on the total molar amount of components (A1 ) and (A2). Preferably, the reaction mixture (R_s) comprises component (A1 ) in an amount of not more than 99.2 mol-%, and more preferably not in an amount of more than 99 mol-%, based on the total molar amount of components (A1 ) and (A2) in the reaction mixture (R_s). The total amount of components (A1 ) and (A2) in the the reaction mixture (R_s) generally adds up to 100%.

The present invention accordingly also provides a method wherein the reaction mixture (R_s) comprises component (A1 ) in an amount of from 90 to 99.5 mol-%, based on the total molar amount of components (A1 ) and (A2) in the reaction mixture (R_s).

Preferably, component (A1 ) comprises not less than 80 wt%, preferably not less than 90 wt%, and more preferably not less than 98 wt% of at least one aromatic dihalogensulfone selected from the group consisting of 4,4'-dichlorodiphenylsulfone and 4,4'-difluorodiphenylsulfone, based on the overall weight of component (A1 ) in reaction mixture (R_s). The weight percentages here in relation to component (A1 ) further relate to the sum total of the 4,4'-dichlorodiphenylsulfone used and of the 4,4'- difluorodiphenylsulfone used. In a further particularly preferred embodiment, component (A1 ) consists essentially of at least one aromatic dihalogensulfone selected from the group consisting of 4,4'- dichlorodiphenyl sulfone and 4,4'-difluorodiphenyl sulfone. What is meant herein by "consisting essentially of" is that component (A1 ) comprises more than 99 wt%, preferably more than 99.5 wt% and more preferably more than 99.9 wt% of at least one aromatic dihalogensulfone selected from the group consisting of 4,4'-dichlorodiphenyl sulfone and 4,4'-difluorodiphenyl sulfone, all based on the overall weight of component (A1 ) in reaction mixture (R_s). In these embodiments, 4,4'-dichlorodiphenyl sulfone is particularly preferable for use as component (A1 ).

In a further particularly preferred embodiment, component (A1 ) consists essentially of 4,4'-dichlorodiphenylsulfone. What is meant herein by "consisting essentially of" is that component (A1 ) comprises more than 99 wt%, preferably more than 99.5 wt% and more preferably more than 99.9 wt% of 4,4'-dichlorodiphenylsulfone. In a further, particularly preferred embodiment, component (A1 ), consists of 4,4'-dichlorodiphenyl- sulfone. Preferably, component (A1 ) is selected from the group consisting of 4,4'-dichlorodiphenylsulfone and 4,4'-difluorodiphenylsulfone.

The present invention accordingly also provides a method wherein component (A1 ) is selected from the group consisting of 4,4'-dichlorodiphenyl sulfone and 4,4'- difluorodiphenyl sulfone.

Said 4,4'-dichlorodiphenylsulfone and 4,4'-difluorodiphenylsulfone may here be used in pure form or as a technical-grade product, which may comprise up to 2 wt%, preferably up to 1 wt% and more preferably up to 0.5 wt% of impurities, all based on the overall weight of the 4,4'-dichlorodiphenyl sulfone used and/or the 4,4'-difluorodiphenyl sulfone used. Any impurities present are included in the wt% particulars relating to component (A1 ).

Component (A2)

Component (A2), which is also referred to as the aromatic dihalogensulfone component comprising at least one -S0₃X group, is present in reaction mixture (R_s) in the form of at least one aromatic dihalogensulfone component comprising at least one -S0₃X group. What is meant herein by "at least one aromatic dihalogensulfone component comprising at least one -S0₃X group" is precisely one aromatic dihalogensulfone component and also mixtures of two or more aromatic dihalogensulfone components comprising at least one -S0₃X group.

Component (A2) comprises at least one -S0₃X group. What is meant herein by "at least one -S0₃X group" is that component (A2) can comprise precisely one -S0₃X group and also two or more -S0₃X groups. The sulfonic acid functional group is characterized as having the general formula -SO₃H . The person skilled in the art knows that the term sulfonic acid functional group also includes derivatives of sulfonic acid functional groups such as sulfonates (-SO₃X), wherein X is hydrogen or a cation equivalent.

By "one cation equivalent" in the context of the present invention is meant one cation of a single positive charge or one charge equivalent of a cation with two or more positive charges, for example Li, Na, K, Mg, Ca, NH₄, preferably Na, K. Component (A2) is present in the reaction mixture (R_s) in an amount of at least 0.5 mol-%, based on the total molar amount of components (A1 ) and (A2) in the reaction mixture (R_s). Preferably, the reaction mixture (R_s) comprises at least 0.8 mol- % and more preferably at least 1 .0 mol-% of component (A2), based on the total molar amount of components (A1 ) and (A2) in the reaction mixture (R_s). The total amount of components (A1 ) and (A2) in the the reaction mixture (R_s) generally adds up to 100%.

Likewise, the reaction mixture (R_s) comprises not more than 10 mol-% of component (A2), based on the total molar amount of components (A1 ) and (A2). Preferably, the reaction mixture (R_s) comprises component (A2) in an amount of not more than 8 mol-%, and more preferably not in an amount of more than 5 mol-%, based on the total molar amount of components (A1 ) and (A2) in the reaction mixture (R_s).

The present invention accordingly also provides a method wherein the reaction mixture (R_s) comprises component (A2) in an amount of from 0.5 to 10 mol-%, based on the total molar amount of components (A1 ) and (A2) in the reaction mixture (R_s).

Component (A2) is preferably selected from the group consisting of 4,4'- dichlorodiphenylsulfone-3,3'-disulfonic acid and 4,4'-difluorodiphenylsulfone-3,3'- disulfonic acid.

The terms "sulfonic acid" and "-S0₃X group" in the context of the present invention are used synonymously and have the same meaning. The term "sulfonic acid" in the 4,4'- dichlorodiphenylsulfone-3,3'-disulfonic acid and 4,4'-difluorodiphenylsulfone-3,3'- disulfonic acid therefore means "-S0₃X group", wherein X is hydrogen or a cation equivalent.

In one embodiment, component (A2) is preferably comprises -S0₃X groups with a cation equivalent. Especially preferably, component (A2) is selected from the group consisting of 4,4'-dichlorodiphenylsulfone-3,3'-disulfonic acid, 4,4'-dichloro- diphenylsulfone-3,3'-disulfonic acid disodium salt, 4,4'-dichlorodiphenylsulfone-3,3'- disulfonic acid dipotassium salt, 4,4'-difluorodiphenylsulfone-3,3'-disulfonic acid, 4,4'- difluorodiphenylsulfone-3,3'-disulfonic acid disodium salt and 4,4'- difluorodiphenylsulfone-3,3'-disulfonic acid dipotassium salt.

The present invention accordingly also provides a method wherein component (A2) is selected from the group consisting of 4,4'-dichlorodiphenylsulfone-3,3'-disulfonic acid, 4,4'-dichloro-diphenylsulfone-3,3'-disulfonic acid disodium salt, 4,4'- dichlorodiphenylsulfone-3,3'-disulfonic acid dipotassium salt, 4,4'- difluorodiphenylsulfone-3,3'-disulfonic acid, 4,4'-difluorodiphenylsulfone-3,3'-disulfonic acid disodium salt and 4,4'-difluorodiphenylsulfone-3,3'-disulfonic acid dipotassium salt.

In one embodiment, component (A2) comprises not less than 80 wt%, preferably not less than 90 wt%, and more preferably not less than 98 wt% of at least one aromatic dihalogensulfone component comprising at least one -S0₃X group selected from the group consisting of 4,4'-dichlorodiphenylsulfone-3,3'-disulfonic acid, 4,4'- dichlorodiphenylsulfone-3,3'-disulfonic acid disodium salt, 4,4'-dichlorodiphenylsulfone- 3,3'-disulfonic acid dipotassium salt, 4,4'-difluorodiphenylsulfone-3,3'-disulfonic acid, 4,4'-difluorodiphenylsulfone-3,3'-disulfonic acid disodium salt and 4,4'- difluorodiphenylsulfone-3,3'-disulfonic acid dipotassium salt, based on the overall weight of component (A2) in the reaction mixture (R_s).

In a further particularly preferred embodiment, component (A2) consists essentially of at least one aromatic dihalogensulfone comprising at least one -S0₃X group selected from the group consisting of 4,4'-dichlorodiphenylsulfone-3,3'-disulfonic acid, 4,4'- dichlorodiphenylsulfone-3,3'-disulfonic acid disodium salt, 4,4'-dichlorodiphenylsulfone- 3,3'-disulfonic acid dipotassium salt, 4,4'-difluorodiphenylsulfone-3,3'-disulfonic acid, 4,4'-difluorodiphenylsulfone-3,3'-disulfonic acid disodium salt and 4,4'- difluorodiphenylsulfone-3,3'-disulfonic acid dipotassium salt. What is meant herein by "consisting essentially of" is that component (A2) comprises more than 99 wt%, preferably more than 99.5 wt% and more preferably more than 99.9 wt% of at least one aromatic dihalogensulfone comprising at least one -S0₃X group selected from the group consisting of 4,4'-dichlorodiphenylsulfone-3,3'-disulfonic acid, 4,4'- dichlorodiphenylsulfone-3,3'-disulfonic acid disodium salt, 4,4'-dichlorodiphenylsulfone- 3,3'-disulfonic acid dipotassium salt, 4,4'-difluorodiphenylsulfone-3,3'-disulfonic acid, 4,4'-difluorodiphenylsulfone-3,3'-disulfonic acid disodium salt and 4,4'- difluorodiphenylsulfone-3,3'-disulfonic acid dipotassium salt, all based on the overall weight of component (A2) in reaction mixture (R_s).

In these embodiments, 4,4'-dichlorodiphenylsulfone-3,3'-disulfonic acid and 4,4'- dichlorodiphenylsulfone-3,3'-disulfonic acid disodium salt are particularly preferable for use as component (A2).

In a further particularly preferred embodiment, component (A2) consists essentially of 4,4'-dichlorodiphenylsulfone-3,3'-disulfonic acid or 4,4'-dichlorodiphenylsulfone-3,3'- disulfonic acid disodium salt. What is meant herein by "consisting essentially of is that component (A2) comprises more than 99 wt%, preferably more than 99.5 wt% and more preferably more than 99.9 wt% of 4,4'-dichlorodiphenylsulfone-3,3'-disulfonic acid or 4,4'-dichlorodiphenylsulfone-3,3'-disulfonic acid disodium salt.

In a further, particularly preferred embodiment, component (A2), consists of 4,4'- dichlorodiphenylsulfone-3,3'-disulfonic acid or 4,4'-dichlorodiphenylsulfone-3,3'- disulfonic acid disodium salt.

Component (B)

Component (B), which is also referred to as the aromatic dihydroxy component, is present in reaction mixture (R_s) in the form of at least one aromatic dihydroxy component. What is meant herein by "at least one aromatic dihydroxy component" is precisely one aromatic dihydroxy component and also mixtures of two or more aromatic dihydroxy components.

Preferably, component (B) is selected from the group consisting of 4,4'- dihydroxybiphenyl, 4,4'-dihydroxydiphenylsulfone, bisphenol A (2,2-bis(4- hydroxyphenyl)propane), 4,4'-dihydroxybenzophenone and hydroquinone. From among the aforementioned aromatic dihydroxy components, 4,4'-dihydroxybiphenyl, 4,4'-dihydroxydiphenyl sulfone and bisphenol A are preferable, while 4,4'- dihydroxybiphenyl is particularly preferable.

The present invention accordingly also provides a method wherein component (B) is selected from the group consisting of 4,4'-dihydroxybiphenyl, 4,4'-dihydroxydiphenyl sulfone, bisphenol A, 4,4'-dihydroxybenzophenone and hydroquinone. Said 4,4'-dihydroxybiphenyl, said 4,4'-dihydroxydiphenyl sulfone, said bisphenol A (2,2- bis(4-hydroxyphenyl)propane), said 4,4'-dihydroxybenzophenone and said hydroquinone may here be used in pure form or as a technical-grade product, which may comprise up to 2 wt%, preferably up to 1 wt% and more preferably up to 0.5 wt% of impurities, all based on the overall weight of the 4,4'-dihydroxybiphenyl, 4,4'- dihydroxydiphenyl sulfone used, the bisphenol A (2,2-bis(4-hydroxyphenyl)propane) used, the 4'4-dihydroxybenzophenone used and the hydroquinone used. Any impurities present are included in the wt% particulars relating to component (B).

Preferably, component (B) comprises not less than 80 wt%, preferably not less than 90 wt% and more preferably not less than 98 wt% of 4,4'-dihydroxybiphenyl, based on the overall weight of component (B) in reaction mixture (R_s). The weight percentages here in relation to component (B) further relate to the sum total of the 4,4'-dihydroxybiphenyl, 4,4'-dihydroxydiphenyl sulfone, bisphenol A (2,2-bis-(4- hydroxyphenyl)propane), 4,4'-dihydroxybenzophenone and hydroquinone used. In a further particularly preferred embodiment, component (B) consists essentially of at least one aromatic dihydroxy component selected from the group consisting of 4,4'- dihydroxybiphenyl, 4,4'-dihydroxydiphenylsulfone, bisphenol A (2,2-bis(4-hydroxy- phenyl)propane), 4,4'-dihydroxybenzophenone and hydroquinone. What is meant herein by "consisting essentially of" is that component (B) comprises more than 99 wt%, preferably more than 99.5 wt% and more preferably more than 99.9 wt% of at least one at least one aromatic dihydroxy component selected from the group consisting of 4,4'-dihydroxybiphenyl, 4,4'-dihydroxydiphenylsulfone, bisphenol A (2,2- bis(4-hydroxyphenyl)propane), 4,4'-dihydroxybenzophenone and hydroquinone, all based on the overall weight of component (B) in reaction mixture (R_s). In these embodiments, 4,4'-dihydroxybiphenyl, bisphenol A and 4,4'-dihydroxydiphenylsulfone are particularly preferable for use as component (B), while 4,4'-dihydroxybiphenyl is most preferable.

It is preferable that the sulfonated polyarylensulfone polymers (sP) have either halogen groups, in particular terminal chlorine groups, or etherified terminal groups, in particularly terminal alkyl ether groups. Etherified terminal groups are obtainable by reacting the terminal OH/phenoxide groups with suitable etherifying agents.

Examples of suitable etherifying agents are monofunctional alkyl or aryl halides, for example C-|-C₆ alkyl chlorides, bromides or iodides, preferably methyl chloride, or benzyl chloride, bromide or iodide, or mixtures thereof. The terminal groups of the sulfonated polyarylenesulfone polymer (sP) according to the present invention are preferably halogen groups, in particular chlorine, and also alkoxy groups, in particular methoxy, aryloxy groups, in particular phenoxy, or benzyloxy.

Organic Polymer of Intrinsic Microporosity (PIM)

Organic polymers of intrinsic microporosity are a class of polymers known to the person skilled in the art. Organic polymers of intrinsic microporosity (PIM)" are polymers with a high free volume, which are characterized by the incorporation of rigid sequences without single-bonded chains in the backbone and kink chains to prevent efficient chain packing.

In principle, it is possible to use any organic polymers of intrinsic microporosity (PIM) that are known to the person skilled in the art and/or can be produced by known methods. Suitable methods of forming the aforementioned organic polymer of intrinsic porosity (PIM) are known per se to a person skilled in the art and are described, for example, in Butt et al., "Solution-processed, organophilic membrane derived from a polymer of intrinsic microporosity", Advanced Materials, 2004, 16, pages 465 to 459 and also in Young et al., "Molecular engineering of PIM-1/Matrimide blend membranes for gas-separation", Journal of Membrane Science, 2012, 407 to 408, pages 47 to 57.

The organic polymer of intrinsic microporosity (PIM) according to the invention is particularly preferably obtained by converting a reaction mixture (R_P) comprising the components (E) and (F) in aprotic polar solvents in the presence of an anhydrous base, wherein the anhydrous base is selected from alkali metal carbonates, alkali metal fluorides and alkali metal hydroxides. In particular, sodium carbonate, potassium carbonate, sodium fluoride or sodium hydroxide or mixtures thereof are being given preference. Components (E) and (F) are reacted with component (B) in a polycondensation reaction. The reaction mixture (R_P) is the mixture which is provided for forming the organic polymer of intrinsic microporosity (PIM). All particulars herein in relation to reaction mixture (R_P) thus relate to the mixture which is present before the polycondensation. It is before the method of the present invention that the polycondensation takes place to convert reaction mixture (R_P) into the target product, the organic polymer of intrinsic microporosity (PIM), by polycondensation of components (E) and (F).

The present invention accordingly also provides a method the polymer of intrinsic microporosity (PIM) is obtained by converting a reaction mixture (R_P) comprising as components:

(E) an aromatic tetrahydroxy component,

(F) an aromatic tetrahalide component.

Component (E)

Reaction mixture (R_P) comprises an aromatic tetrahydroxy component as component (F), which is present in the reaction mixture (R_P) in the form of at least one aromatic tetrahydroxy component. What is meant herein by "at least one aromatic tetrahydroxy component" is precisely one aromatic tetrahydroxy component and also mixtures of two or more aromatic tetrahydroxy components.

Preferably, the reaction mixture (R_P) comprises component (E) in an amount of from 30 to 70 mol-%, preferably 40 to 60 mol-% and especially 50 mol-%, based on the total molar amount of components (E) and (F) in the reaction mixture (R_P). The total amount of components (E) and (F) in the the reaction mixture (R_P) adds up to 100%. The present invention accordingly also provides a method wherein the reaction mixture (R_P) comprises component (E) in an amount of from 30 to 70 mol-%, based on the total molar amount of components (E) and (F) in the reaction mixture (R_P). Preferably, component (E) is a compound selected from the group consisting of 5,5',6,6'-tetrahydroxy-3,3,3',3'-tetramethylspirobisindane, 2,2',3,3'-tetrahydroxy-1 , 1 '- binaphthyl, 5,5',6,6'-tetrahydroxy-1 , 1 '-spirobisindane-3,3'-bis-fluorene, 6, 6', 7,7'- tetrahydroxy-4,4,4',4'-tetramethyl-2,2'-spirobischromane, 2,2', 3, 3'- tetrahydroxybiphenyl. Very preferably, component (E) is 5,5',6,6'-tetrahydroxy-3,3,3',3'- tetramethylspirobisindane.

The present invention accordingly also provides a method wherein component (E) is selected from the group consisting of 5,5',6,6'-tetrahydroxy-3,3,3',3'-tetramethyl- spirobisindane, 2,2',3,3'-tetrahydroxy-1 ,1 '-binaphthyl, 5,5',6,6'-tetrahydroxy-1 , 1 '- spirobisindane-3,3'-bis-fluorene, 6,6',7,7'-tetrahydroxy-4,4,4',4'-tetramethyl-2,2'- spirobischromane, 2,2',3,3'-tetrahydroxybiphenyl.

In one embodiment, component (E) comprises not less than 80 wt%, preferably not less than 90 wt%, and more preferably not less than 98 wt% of 5,5',6,6'-tetrahydroxy- 3,3,3',3'-tetramethylspirobisindane, based on the overall weight of component (E) in reaction mixture (R_P).

In a further particularly preferred embodiment, component (E) consists essentially of 5,5',6,6'-tetrahydroxy-3,3,3',3'-tetramethylspirobisindane. What is meant herein by "consisting essentially of" is that component (E) contains more than 99 wt%, preferably more than 99.5 wt% and more preferably more than 99.9 wt% of 5,5',6,6'-tetrahydroxy- 3,3,3',3'-tetramethylspirobisindane, all based on the overall weight of component (E) in reaction mixture (R_P). In a further particularly preferred embodiment, component (E) consists of 5, 5', 6, 6'- tetrahydroxy-3,3,3',3'-tetramethylspirobisindane.

Component (F) Reaction mixture (R_P) comprises an aromatic tetrahalide component as component (F), which is present in the reaction mixture (R_P) in the form of at least one aromatic tetrahalide component. What is meant herein by "at least one aromatic tetrahalide component" is precisely one aromatic tetrahalide component and also mixtures of two or more aromatic tetrahalide components.

The reaction mixture (R_P) comprises component (F) in an amount of 70 to 30 wt%, based on the overall weight of component (F) in the reaction mixture (R_P). Preferably, the reaction mixture (R_P) comprises component (F) in an amount of 60 to 40 wt%, and especially in an amount of 50 wt%, based on the total molar amount of component (F) present in the reaction mixture (R_P). The total amount of components (E) and (F) in the the reaction mixture (R_P) adds up to 100%.

The present invention accordingly also provides a method wherein the reaction mixture (R_P) comprises component (F) in an amount of from 70 to 30 mol-%, based on the total molar amount of components (E) and (F) in the reaction mixture (R_P). Preferably, component (F) is selected from the group consisting of 2,3,5,6- tetrafluoroterephthalonitrile, heptafluoro-p-tolylphenylsulfone, 1 ,2,4,5-tetrafluoro-3,6- bis(ethylsulfonyl)benzene, 1 ,2,4,5-tetra-fluoro-3,6-bisphenylsulfonylbenzene, 1 ,2,4,5- tetrafluoro-3,6-bis(methoxy-4-phenyl-sulfonyl)benzene, 2,3,7,8-tetrafluoro-5,5', 10, 10'- tetraoxidethianthrene. Very preferably, component (F) is 2,3,5,6-tetrafluoro- terephthalonitrile.

The present invention accordingly also provides a method wherein component (F) is selected from the group consisting of 2,3,5,6-tetrafluoroterephthalonitrile, heptafluoro- p-tolylphenylsulfone, 1 ,2,4,5-tetrafluoro-3,6-bis(ethylsulfonyl)-benzene, 1 ,2,4,5-tetra- fluoro-3,6-bisphenylsulfonylbenzene, 1 ,2,4,5-tetrafluoro-3,6-bis(methoxy-4-phenyl- sulfonyl)benzene, 2,3,7,8-tetrafluoro-5,5', 10,10'-tetraoxidethianthrene.

In one embodiment, component (F) comprises not less that 80 wt%, preferably not less than 90 wt% and very preferably not less than 98 wt% of 2,3,5,6- tetrafluoroterephthalonitrile, based on the overall weight of components (F) present in the reaction mixture (R_P).

In another preferred embodiment, component (F) consists essentially of 2,3,5,6- tetrafluoroterephthalonitrile. What is meant herein by "consisting essentially of is that component (F) comprises more than 99 wt%, preferably more than 99.5 wt% and more preferably more than 99.9 wt% of 2,3,5,6-tetrafluoroterephthalonitrile, based on the overall weight of component (F) in reaction mixture (R_P).

In a further particularly preferred embodiment, component (F) consists of 2,3,5,6- tetrafluoroterephthalonitrile.

The terminal groups of the organic polymer of intrinsic porosity (PIM) depend on the reaction conditions and the molar ratios of components (E) and (F) and are generally preferably either terminal fluorine groups or etherified groups, in particular terminal alkyl ether groups. Terminal etherified groups are obtained by reacting the terminal OH/phenoxide groups with suitable etherifying agents. Step ii)

In step ii), the at least one solvent is separated from the solution to obtain the membrane (M). In one embodiment the solution (S) provided in step i) is filtered to obtain a filtered solution (fS), before the at least one solvent is separated in step ii). The following information for separating the at least one solvent from the solution (S) applies equally for separating the at least one solvent from the filtered solution (fS).

The separation of the sulfonated polyarylenesulfone polymer (sP) and the organic polymer of intrinsic microporosity (PIM) from the at least one solvent can be performed by any process known to the skilled person, which is suitable to separate polymers from solvents.

The separation in step ii) can be performed by a phase inversion process.

A phase inversion process within the context of the present invention means a process wherein the dissolved sulfonated polyarylenesulfone polymer (sP) and the dissolved organic polymer of intrinsic microporosity (PIM) are transformed to a solid phase. Therefore, a phase inversion process can also be denoted as a precipitation process. According to step ii), the transformation is performed by separation of the sulfonated polyarylenesulfone polymer (sP) and the organic polymer of intrinsic microporosity (PIM) from the at least one solvent. The person skilled in the art knows suitable phase inversion processes. The phase inversion process can, for example, be performed by evaporation of the at least one solvent comprised in the solution (S). It is also possible to cool down the solution (S). During this cooling down, the sulfonated polyarylenesulfone polymer (sP) and the organic polymer of intrinsic microporosity (PIM) comprised in the solution (S) precipitate. Another possibility to perform the phase inversion process is to bring the solution (S) in contact with a gaseous liquid that is a non-solvent for the sulfonated polyarylenesulfone polymer (sP) and the organic polymer of intrinsic microporosity (PIM). The sulfonated polyarylenesulfone polymer (sP) and the organic polymer of intrinsic microporosity (PIM) will then as well precipitate. Suitable gaseous liquids that are non-solvents for the sulfonated polyarylenesulfone polymer (sP) and the organic polymer of intrinsic microporosity (PIM) are for example the protic polar solvents described hereinafter in their gaseous state. Another phase inversion process which is preferred within the context of the present invention is the phase inversion by immersing the solution (S) into at least one protic polar solvent. Therefore, in one embodiment of the present invention, in step ii) the sulfonated polyarylenesulfone polymer (sP) and the organic polymer of intrinsic microporosity (PIM) comprised in the solution (S) are separated from the at least one solvent comprised in the solution (S) by immersing the solution (S) into at least one protic polar solvent.

This means that the membrane (M) is formed by immersing the solution (S) into at least one protic polar solvent.

Suitable at least one protic polar solvents are known to the skilled person. The at least one protic polar solvent is preferably a non-solvent for the sulfonated polyarylenesulfone polymer (sP) and the organic polymer of intrinsic microporosity (PIM).

Preferred at least one protic polar solvents are water, methanol, ethanol, n-propanol, iso-propanol, glycerol, ethyleneglycol and mixtures thereof. Step ii) usually comprises a provision of the solution (S) in a form that corresponds to the form of the membrane (M) which is obtained in step ii).

Therefore, in one embodiment of the present invention, step ii) comprises a casting of the solution (S) to obtain a film of the solution (S) or a passing of the solution (S) through at least one spinneret to obtain at least one hollow fiber of the solution (S).

Therefore, in one preferred embodiment of the present invention, step ii) comprises the following steps. ii-1 ) casting the solution (S) provided in step i) to obtain a film of the solution (S), ii-2) evaporating the at least one solvent from the film of the solution (S) obtained in step ii-1 ) to obtain the membrane (M) which is in the form of a film.

This means that the membrane (M) is formed by evaporating the at least one solvent from a film of the solution (S).

In step ii-1 ), the solution (S) can be cast by any method known to the skilled person. Usually, the solution (S) is cast with a casting knife that is heated to a temperature in the range from 20 to 150°C, preferably in the range from 80 to 100°C.

The solution (S) is usually cast on a substrate that does not react with the sulfonated polyarylenesulfone (sP), the organic polymer of intrinsic microporosity (PIM) or the at least one solvent comprised in the solution (S). Suitable substrates are known to the skilled person and are, for example, selected from glass plates and polymer fabrics such as non-woven materials. Membrane (M)

In step ii), the membrane (M) is obtained. The sulfonated polyarylenesulfone polymer (sP) and the organic polymer of intrinsic microporosity (PIM) are preferably homogeneously distributed in the membrane (M).

The membrane (M) comprises generally in the range from 80 to 99% by weight, especially in an amount of 90 to 98% by weight of the organic polymer of intrinsic microporosity (PIM) and in the range from 1 to 20% by weight, especially in an amount of 2 to 10% by weight of the sulfonated polyarylenesulfone polymer (sP), based on the sum of the percent by weight of the organic polymer of intrinsic microporosity (PIM) and the sulfonated polyarylenesulfone polymer (sP), preferably based on the total weight of the membrane (M).

The present invention accordingly also provides a method wherein the membrane (M) comprises 80 to 99% by weight of the organic polymer of intrinsic microporosity (PIM) and 1 to 20% by weight of the sulfonated polyarylenesulfone polymer(sP), based on the total weight of the membrane (M).

During the formation of the membrane (M), the sulfonated polyarylenesulfone polymer (sP) and the organic polymer of intrinsic microporosity (PIM) are separated from the at least one solvent. Therefore, the obtained membrane (M) is essentially free from the at least one solvent. "Essentially free" within the context of the present invention means that the membrane (M) comprises at most 1 % by weight, preferably at most 0.5% by weight and particularly preferably at most 0.1 % by weight of the at least one solvent, based on the total weight of the membrane (M). The membrane (M) comprises at least 0.0001 % by weight, preferably at least 0.001 % by weight and particularly preferably at least 0.01 % by weight of the at least one solvent, based on the total weight of the membrane (M).

The present invention also provides the membrane (M) which is obtained by the method of the present invention. The present invention further provides a method of using the membrane (M) obtained by the method of the present invention for the separation of gases from gas mixtures.

The present invention is more particularly elucidated by the following examples without being restricted thereto. Components used:

DCDPS: 4,4'-dichlorodiphenyl sulfone

DDDA: diphenylsulfone-4,4'-dichloro-3,3'-disulfonic acid disodium salt DHB: 4,4'-dihydroxybiphenyl

TTSBI: 5,5',6,6'-tetrahydroxy-3,3,3',3'-tetramethylspirobisindane

TFTPN: 2,3,5,6-tetrafluoroterephthalonitrile

PIM-1 : organic polymer of intrinsic microporosity (PIM) obtained from the reaction of TTSBI and TFTPN

PPSU: polyphenylenesulfone

sPPSU: sulfonated polyphenylenesulfone potassium carbonate: K₂C0₃, anhydrous,

NMP: N-methylpyrrolidone, anhydrous

dichloromethane

chloroform

Synthesis of the sulfonated polyarylenesulfone polymer (sP); sulfonated polyphenylenesulfone (sPPSU)

Synthesis of sPPSU-1 .5 with 1 .5 mol-% of component (A2)

In a 4 I vessel equipped a with stirrer, Dean-Stark-trap, nitrogen inlet and temperature control, a reaction mixture (R_s) was provided, by suspending 577.04 g (2.01 mol) of 4,4'-dichlorodiphenylsulfone (DCDPS; component A1 ), 372.42 g (2.00 mol) of 4,4'- dihydroxybiphenyl (DHB; component B), 14.86 g (0.03 mol) of 4,4'- dichlorodiphenylsulfone-3,3'-disulfonic acid disodium salt (component A2) and 293.01 g (2.12 mol) of potassium carbonate (particle size: 39.3 μηη) under nitrogen atmosphere in 2 I of NMP. The reaction mixture (R_s) was heated to 190°C under stirring. The reaction mixture (R_s) was kept at 190°C for 6 h, during which nitrogen was purged through the reaction mixture (R_s) at 30 l/h. Subsequently, 1 L of NMP was added and the reaction mixture (R_s) was cooled down to 60 °C under nitrogen. The reaction mixture (R_s) was filtered and precipitated in water comprising 100 ml HCI (2 M). The precipitated product was extracted with hot water for 20 h at 85°C and dried at 120°C for 24 h under reduced pressure to obtain the sulfonated polyphenylene sulfone (sPPSU-1 .5), which comprises 1 .5 mol-% of component (A2), based on the total molar amount of components (A1 ) and (A2) in the reaction mixture (R_s).

Viscosity number: 66.7 ml/g (1 wt/vol-% solution in NMP at 25°C);

T_g = 224° ± 1 °C

Synthesis of sPPSU-2.5 with 2.5 mol-% of component (A2) In a 4 I vessel equipped a with stirrer, Dean-Stark-trap, nitrogen inlet and temperature control, a reaction mixture (R_s) was provided, by suspending 568.42 g (1 .98 mol) of 4,4'-dichlorodiphenylsulfone (DCDPS; component A1 ), 372.42 g (2.00 mol) of 4,4'- dihydroxybiphenyl (DHB; component B), 24.76 g (0.05 mol) of 4,4'- dichlorodiphenylsulfone-3,3'-disulfonic acid disodium salt (component A2) and 293.01 g (2.12 mol) of potassium carbonate (particle size: 39.3 μηη) under nitrogen atmosphere in 2 I of NMP. The reaction mixture (R_s) was heated to 190°C under stirring. The reaction mixture (R_s) was kept at 190°C for 6 h, during which nitrogen was purged through the reaction mixture (R_s) at 30 l/h. Subsequently, 1 L of NMP was added and the reaction mixture (R_s) was cooled down to 60 °C under nitrogen. The reaction mixture (R_s) was filtered and precipitated in water comprising 100 ml HCI (2 M). The precipitated product was extracted with hot water for 20 h at 85°C and dried at 120°C for 24 h under reduced pressure to obtain the sulfonated polyphenylene sulfone (sPPSU-2.5), which comprises 2.5 mol-% of component (A2), based on the total molar amount of components (A1 ) and (A2) in the reaction mixture (R_s).

Viscosity number: 66.4 ml/g (1 wt/vol-% solution in NMP at 25°C);

T_g = 226° ± 1 °C

Synthesis of sPPSU-3.5 with 3.5 mol-% of component (A2)

In a 4 I vessel equipped a with stirrer, Dean-Stark-trap, nitrogen inlet and temperature control, a reaction mixture (R_s) was provided, by suspending 561 .24 g (1 .95 mol) of 4,4'-dichlorodiphenylsulfone (DCDPS; component A1 ), 372.42 g (2.00 mol) of 4,4'- dihydroxybiphenyl (DHB; component B), 34.67 g (0.07 mol) of 4,4'- dichlorodiphenylsulfone-3,3'-disulfonic acid disodium salt (component A2) and 293.01 g (2.12 mol) of potassium carbonate (particle size: 39.3 μηη) under nitrogen atmosphere in 2 I of NMP. The reaction mixture (R_s) was heated to 190°C under stirring. The reaction mixture (R_s) was kept at 190°C for 6 h, during which nitrogen was purged through the reaction mixture (R_s) at 30 l/h. Subsequently, 1 L of NMP was added and the reaction mixture (R_s) was cooled down to 60 °C under nitrogen. The reaction mixture (R_s) was filtered and precipitated in water comprising 100 ml HCI (2 M). The precipitated product was extracted with hot water for 20 h at 85°C and dried at 120°C for 24 h under reduced pressure to obtain the sulfonated polyphenylene sulfone (sPPSU-3.5), which comprises 3.5 mol-% of component (A2), based on the total molar amount of components (A1 ) and (A2) in the reaction mixture (R_s).

Viscosity number: 63.3 ml/g (1 wt/vol-% solution in NMP at 25°C);

Synthesis of PIM-1 A reaction mixture (R_P) was prepared by dissolving 5,5',6,6'-tetrahydroxy-3,3,3',3'- tetramethylspirobisindane (TTSBI , component E) and 2,3,5,6- tetrafluoroterephthalonitrile (TFTPN, component F) in equimolar amounts with a stoichiometric amount of anhydrous potassium carbonate in NMP under a nitrogen atmosphere. The reaction mixture (R_P) was purged with nitrogen for 30 min to remove trapped moisture and air prior to heating up to 60°C. The reaction mixture (R_P) was stirred and kept at 60°C for 24 h, after which the reaction mixture (R_P) was precipitated and washed with methanol. The obtained solid was washed in a 0.1 wt-% HCI solution to remove the carbonate. The product was filtered, washed with deionized water and methanol. The obtained organic polymer PIM-1 was dried at 120°C under vacuum for 24 h.

The polymer was characterized by GPC in THF (PS-calibration, Rl-detector):

M_w: 52,000 g/mol

Preparation of the membrane (M)

Dense films of a membrane (M) which comprises PIM-1 and sPPSU were prepared via solution casting. sPPSU and PIM-1 were simultaneously dissolved in DCM or CHCI₃ or a solvent mixture comprising DCM and CHCI₃ and were stirred over night to obtain the solution (S). The total amount of PIM-1 and sPPSU in the solution (S) is 2% by weight, based on the total weight of the solution (S). The weight ratio of PIM-1 to sPPSU in the solution (S) varies from 98: 2, 95 : 5, 90 : 10, 85 : 15 and 80 : 20, based on the total weight sum of PIM-1 and sPPSU. The solution (S) was subsequently filtered through a 1 to 5 μηη PTFE (polytetrafluoroethylene) filter to obtain the filtered solution (fS). The filtered solution (fS) was cast onto a leveled silicon wafer at 20 °C. A slow casting method was used to induce a slower solvent evaporation rate. Dense films of a membrane (M) were formed when most of the solvent evaporated at 20 °C after 6 to 9 days. The resultant films were dried at 120 °C under vacuum for at least 8 h.

For a better comparison, membranes (M) comprising only PIM-1 , PPSU, sPPSU or a blend of PIM-1 and PPSU were prepared in an analogous manner as described above.

Gas permeation properties of the membrane (M)

The rate of the pressure increase (dp/dt) at a steady state was used to calculate the gas permeability of the membrane (M) as follows:

where P is the gas permeability of the membrane (M) in Barrer (1 Barrer = 1 10^"10 cm³ / s x cm x cmHg), V is the volume of the downstream chamber (cm³), A refers to the effective area (cm²) of the membrane (M), / is the thickness (cm) of the membrane (M), T is the operating temperature (K), p₂ is defined as the upstream operating pressure (psia).

The ideal selectivity is the ratio of pure-gas permeability of a gas pair across the membrane (M) as described below:

a =— PA

P_B

where P_A and P_B are the gas permeability of gases A and B, respectively.

Table 1 summarizes all the gas permeability and selectivity properties of membranes (M) composed of PPSU or its sulfonated derivatives sPPSU. The sPPSU used was prepared from a reaction mixture (R_s) comprising DCDPS, DHB and DDDA, wherein the amount of DDDA in the reaction mixture (R_s) respectively was 1 .5 mol-% (sPPSU- 1 .5), 2.5 mol-% (sPPSU-2.5) or 3.5 mol-% (sPPSU-3.5), based on the total molar amount of DCDPS and DDDA in the reaction mixture (R_s). The pure gas permeability was measured using a variable-pressure constant-volume gas permeation cell. Table 1 (Comparative Examples).

Permeability (Barrer) Selectivity

Membrane

H₂ o₂ N₂ CH₄ co₂ H₂/N₂ 0₂/N_: ₂ C0₂/N₂ C0₂/CH₄

PPSU 12.9 1.70 0.28 0.32 8.0 46.1 6.1 28.6 25.0 sPPSU-1.5 14.3 1.55 0.29 0.33 8.3 49.3 5.3 28.6 25.2 sPPSU-2.5 14.5 1.69 0.30 0.32 8.0 48.3 5.6 26.7 25.0 sPPSU-3.5 13.1 1.63 0.30 0.30 7.5 43.7 5.4 25.0 25.0

These data show that the increase of the degree of sulfonation from PPSU to sPPSU-3.5 does not result in any significant differences in the permeability and the selectivity properties of the respective membranes (M). The membranes (M) have comparable and high selectivities, but a relatively low permeability for the separation of 0₂/N₂, C0₂/N₂ and C0₂/CH₄ gas mixtures.

Table 2 exhibits the gas separation performance of membranes (M) composed of PIM-1 or blends of PIM-1 and PPSU as a function of the ratio of PIM-1 to PPSU.

Table 2 (Comparative Examples).

Permeability (Barrer) Selectivity

Membrane

H₂ o₂ N₂ CH₄ co₂ H₂/N₂ 0₂/N₂ C0₂/N₂ C0₂/CH₄

PIM-1 4000 1073 338 502 5506 1 1.8 3.2 16.3 1 1.0

PIM-1/PPSU

2783 1047 360 547 5763 7.7 2.9 16.0 10.5

(95/5)^a

PIM-1/PPSU 2438 835 282 410 4197 8.6 3.0 14.9 10.2 (90/10)^a

PIM-1/PPSU

1670 599 184 207 2550 9.1 3.3 13.9 12.3 (85/15)^a

PPSU 12.9 1.70 0.28 0.32 8.0 46.1 6.1 28.6 25.0 a The values in brackets refer to % by weight, based on the total weight sum of PIM-1 and PPSU.

The addition of PPSU to PIM-1 causes negligible changes in the selectivities and reduces the permeability of the membranes (M).

Table 3 summarizes the gas separation performance of membranes (M) comprising blends of PIM-1 and sPPSU. The gas separation performance of the membranes (M) is shown depending on the ratio of PIM-1 to sPPSU and as a function of the degree of sulfonation. PIM-1 was blended with sPPSU which was prepared from a reaction mixture (R_s) comprising DCDPS, DHB and DDDA and in which the amount of DDDA respectively was 1.5 mol-% (sPPSU-1 .5), 2.5 mol-% (sPPSU-2.5) or 3.5 mol-% (sPPSU-3.5), based on the total molar amount of DCDPS and DDDA in the reaction mixture (R_s). Comparative examples not according to the present invention are marked with (C).

Table 3.

Permeability (Barrer) Selectivity

Membrane

H₂ o₂ N₂ CH₄ co₂ H₂/N₂ 0₂/N_: ₂ C0₂/N₂ C0₂/CH₄

PIM-1 (C) 4000 1073 338 502 5506 1 1.8 3.2 16.3 1 1.0

PIM-l/sPPSU-1.5

1834 441 105 128 2266 17.5 4.2 21.6 17.7

(95/5)^a

PIM-l/sPPSU-1.5

1145 265 62 69 1308 18.5 4.3 21.1 19.0

(90/10)^a

PIM-l/sPPSU-1.5

982 192 42 49 1049 23.4 4.6 25.0 21.4

(80/20)^a

sPPSU-1.5 (C) 14.3 1.55 0.29 0.33 8.3 49.3 5.3 28.6 25.2

PIM-1/SPPSU-2.5

1659 408 97 1 19 2343 17.1 4.2 24.2 19.7

(95/5)^a

PIM-1/SPPSU-2.5

1147 265 62 75 1532 18.5 4.3 24.7 20.4

(90/10)^a

PIM-1/SPPSU-2.5

502 70 14 14 355 35.9 5.0 25.4 25.4

(80/20)^a

sPPSU-2.5 (C) 14.5 1.69 0.30 0.32 8.0 48.3 5.6 26.7 25.0

PIM-1/SPPSU-3.5

2689 615 131 167 3003 20.5 4.7 22.9 18.0

(95/5)^a

PIM-1/SPPSU-3.5

1899 395 83 100 2003 22.9 4.8 24.1 20.0

(90/10)^a

PIM-1/SPPSU-3.5

1257 257 57 61 1429 22.1 4.5 25.1 23.4

(80/20)^a

sPPSU-3.5 (C) 13.1 1.63 0.30 0.30 7.5 43.7 5.4 25.0 25.0 a The values in brackets refer to % by weight, based on the total weight sum of PIM-1 and sPPSU. Compared to pure PPSU , the membranes (M) comprising sPPSU-1 .5, sPPSU-2.5 and sPPSU-3.5 show significant increases in the selectivities for H₂/N₂, 0₂/N₂, C0₂/N₂ and C0₂/CH₄ gas mixtures. The presence of 5 to 20% by weight of sPPSU, based on the 5 total weight sum of PIM-1 and sPPSU, increases the selectivities of the membrane (M) for these gas mixtures. The resulting selectivities are close and even comparable to the selectivity of pure sPPSU. This phenomenon outperforms the ordinary trend observed in polymer blends, where the permeability or selectivity of a blend is normally close to one of the original polymers which is physically dominant in terms of weight or volume 10 in the blend system.

In comparison to pure sPPSU-3.5, the C0₂/CH₄ and 0₂/N₂ selectivities of a membrane (M) composed of PIM-1 and sPPSU-3.5 in a weight ratio of 90 : 10, based on the total weight sum of PIM-1 and sPPSU, only decreases by 6.3%, and 17%, respectively. 15 However, the C0₂ and 0₂ permeability increases by 189- and 157-folds compared to the respective permeability of pure sPPSU-3.5. The greater separation performance indicates that the presence of -S0₃X groups promotes strong molecular interactions with C0₂ and 0₂ in membranes (M) comprising PIM-1 and sPPSU . In addition, the -SO₃X groups may interact with PIM-1 and thus enhance the chain packing.

20

Solubility of PIM-1 and sPPSU

The dissolution properties of PPSU and sPPSU were determined in CHCI₃ and DCM, because they are solvents in which PIM-1 is soluble. Qualitative solubility was determined by preparing a solution (S) comprising PPSU or sPPSU and a solvent at 25 20 °C, in which the total amount of PPSU or sPPSU was 2% by weight, based on the total weight of the solution (S). CHCI₃ (chloroform); DCM (dichloromethane); + + (completely dissolved); + - (partially soluble); - (insoluble).

Table 4.

Polymer CHCI₃ DCM

PPSU +-^~

sPPSU-1.5 ++ ++

sPPSU-2.5 ++ ++

sPPSU-3.5 ++ +-

30

As summarized in Table 4, PPSU is only partially soluble in CHCI₃. sPPSU-1 .5, sPPSU-2.5 and sPPSU-3.5 are all soluble in CHCI₃. These polymers, however, have different solubility behaviors in DCM compared to CHCI₃. While PPSU is completely insoluble in DCM, sPPSU-1 .5 and sPPSU-2.5 are soluble in DCM, but sPPSU-3.5 35 becomes partially insoluble in DCM.

In order to find an at least one solvent suitable for the solution (S), the solubility of PIM-1 and sPPSU-3.5 in a weight ratio of 90 : 10, based on the total weight sum of PIM-1 and sPPSU, was investigated in pure CHCI₃, DCM and in a solvent mixture of CHCI₃ and DCM. A translucent solution is a primary indication in order to obtain a homogeneous film of a membrane (M).

A dynamic light scattering sensor was employed to quantitatively validate the co- solvent effect on phase separation and immiscibility of PIM-1 and sPPSU-3.5 in the solution (S). The automated particle sizer can detect particle sizes ranging from 2 nm to 3 μηη. The characteristic outputs are the effective diameter of the polymer particles and the polydispersity.

Polydispersity is defined as the intensity of light weighting over an average process. Polydispersity has no unit. Its value is close to zero (0.000 to 0.020) for monodisperse samples, small (0.020 to 0.080) for narrow distributions, but large for broad distributions.

Figure 1 shows that the solution (S) comprising PIM-1 , sPPSU-3.5 and a solvent mixture of DCM and CHCI₃ exhibits relatively smaller particle sizes than solutions (S) comprising PIM-1 , sPPSU-3.5 and pure DCM or CHCI₃.

Similarly, Figure 2 shows that the solution (S) comprising PIM-1 , sPPSU-3.5 and a solvent mixture of DCM and CHCI₃ also has lower polydispersity compared to those solutions (S) comprising pure solvents. These results suggest that solvent mixtures induce better dissolution with minimal agglomeration than pure solvents. Since PIM-1 and sPPSU-3.5 comprise no inorganic filler, the detected particle size is likely formed by the agglomeration of polymer chains. As the solution (S) comprising a solvent mixture of CHCI₃ and DCM in a ratio of 2 : 1 has the lowest polydispersity and the smallest particle size, the ratio of CHCI₃ to DCM of 2 : 1 maximizes the solubility of PIM-1 and sPPSU-3.5 in the solution (S). Thus, this ratio of the solvent mixture in the solution (S) is selected for the casting of the membrane (M).

Claims

A method for the preparation of a membrane (M) which comprises an organic polymer of intrinsic microporosity (PIM) and a sulfonated polyarylenesulfone polymer (sP), wherein the process comprises the steps: i) providing a solution (S) which comprises the organic polymer of intrinsic microporosity (PIM), the sulfonated polyarylenesulfone polymer (sP) and at least one solvent,

The method according to claim 1 , wherein the sulfonated polyarylenesulfone polymer (sP) has the general formula I:

where t and q : are each independently 0, 1 , 2 or 3,

Q, T and Y: are each independently a chemical bond or selected from -0-,

-S-, -S0₂- -S(=0)-, -C(=0)-, -N=N- and -CR^aR^b- wherein R^a and R^b are each independently a hydrogen atom or a CrC₁₂-alkyl, d-C₁₂-alkoxy or C₆-C₁₈-aryl group, and wherein at least one of Q, T and Y is -S0₂-

X: is hydrogen or one cation equivalent.

3. The method according to claim 1 or 2, wherein the polyarylenesulfone polymer EB15-9441 PC (sP) is obtained by converting a reaction mixture (R_s) comprising as components:

(A1 ) an aromatic dihalogensulfone component,

(A2) an aromatic dihalogensulfone component comprising at least one -S0₃X group, wherein X is hydrogen or a cation equivalent,

(B) an aromatic dihydroxy component.

The method according to claim 3, wherein the reaction mixture (R_s) comprises component (A1 ) in an amount of from 90 to 99.5 mol-% and component (A2) in an amount of from 0.5 to 10 mol-%, based on the total molar amount of components (A1 ) and (A2) in the reaction mixture (R_s).

The method according to claim 3 or 4, wherein component (A1 ) is selected from the group consisting of 4,4'-dichlorodiphenyl sulfone and 4,4'-difluorodiphenyl sulfone.

The method according to any of claims 3 to 5, wherein component (A2) is selected from the group consisting of 4,4'-dichlorodiphenylsulfone-3,3'-disulfonic acid, 4,4'-dichloro-diphenylsulfone-3,3'-disulfonic acid disodium salt, 4,4'- dichlorodiphenylsulfone-3,3'-disulfonic acid dipotassium salt, 4,4'- difluorodiphenylsulfone-3,3'-disulfonic acid, 4,4'-difluorodiphenylsulfone-3,3'- disulfonic acid disodium salt and 4,4'-difluorodiphenylsulfone-3,3'-disulfonic acid dipotassium salt.

The method according to any of claims 3 to 6, wherein component (B) is selected from the group consisting of 4,4'-dihydroxybiphenyl, 4,4'-dihydroxy- diphenyl sulfone, bisphenol A, 4,4'-dihydroxybenzophenone and hydroquinone.

The method according to any of claims 1 to 7, wherein the polymer of intrinsic microporosity (PIM) is obtained by converting a reaction mixture (R_P) comprising as components:

(E) an aromatic tetrahydroxy component,

(F) an aromatic tetrahalide component.

The method according to claim 8, wherein the reaction mixture (R_P) comprises component (E) in an amount of from 30 to 70 mol-% and component (F) in an amount of from 70 to 30 mol-%, based on the total molar amount of components (E) and (F) in the reaction mixture (R_P).

10. The method according to claim 8 or 9, wherein component (E) is selected from the group consisting of 5,5',6,6'-tetrahydroxy-3,3,3',3'-tetramethyl- spirobisindane, 2,2',3,3'-tetrahydroxy-1 , 1 '-binaphthyl, 5,5',6,6'-tetrahydroxy-1 , 1 '- spirobisindane-3,3'-bis-fluorene, 6,6',7,7'-tetrahydroxy-4,4,4',4'-tetramethyl-2,2'- spirobischromane, 2,2',3,3'-tetrahydroxybiphenyl.

1 1 . The method according to any of claims 8 to 10, wherein component (F) is selected from the group consisting of 2,3,5,6-tetrafluoroterephthalonitrile, heptafluoro-p-tolylphenylsulfone, 1 ,2,4,5-tetrafluoro-3,6-bis(ethylsulfonyl)- benzene, 1 ,2,4,5-tetra-fluoro-3,6-bisphenylsulfonylbenzene, 1 ,2,4,5-tetrafluoro-

3,6-bis(methoxy-4-phenyl-sulfonyl)benzene, 2,3,7,8-tetrafluoro-5,5',10, 10'- tetraoxidethianthrene.

12. The method according to any of claims 1 to 1 1 , wherein the membrane (M) comprises 80 to 99% by weight of the organic polymer of intrinsic microporosity

(PIM) and 1 to 20% by weight of the sulfonated polyarylenesulfone polymer(sP), based on the total weight of the membrane (M).

13. The method according to any of claims 1 to 12, wherein the total amount of the organic polymer of intrinsic microporosity (PIM) and the sulfonated polyarylenesulfone polymer (sP) in the solution (S) is 0.1 to 20% by weight, based on the total weight of the solution (S).

14. The membrane (M) obtained according to the method of claims 1 to 13.

15. Use of a membrane (M) obtained according to the method of claims 1 to 13 for the separation of gases from gas mixtures.