Poly(arylene ether sulfone) polymer membranes

Abstract

The present invention relates to a membrane comprising two different poly(arylene ether sulfone) polymers (P1) and (P2) as well as a thermoplastic polyurethane (TPU), a method for producing the same and a dope solution for preparing such membrane.

Description

[0001] 241410

[0002] 1

[0003] Poly(arylene ether sulfone) polymer membranes

[0004] Field of the Invention

[0005] The present invention relates to a membrane comprising two different poly(arylene ether sulfone) polymers (P1) and (P2) as well as a thermoplastic polyurethane (TPU), a method for producing the same and a dope solution for preparing such membrane.

[0006] Background

[0007] Membrane technologies have reached a lot of attention during the last decades. In several application areas membranes are used for the energy efficient separation of mixtures. Particularly, membranes are widely used for water purification (J.-C. Schrotter, B. Bozkaya-Schrotter in ,, Membranes for Water Treatment", Ed. K.-V.

[0008] Peinemann, S. Pereira Nunes, Wiley-VCH, Vol. 4, 2010). Another important field of use for specific membranes is the purification of blood, in particular blood dialysis (hemodialysis) or blood filtration dialysis therapies that are necessary in the treatment of people suffering from renal kidney disease (C.R. Ronco, W.R. Clark, Nature Reviews Nephrology, 14, 2018, 394).

[0009] Today, poly(aryl sulfone) and poly(vinyl idene fluoride) polymers are used as matrix materials in ultra / microfiltration (UF / MF) membranes for multiple applications. In addition to general features such as good chemical resistance and high thermal stability it is known that UF / MF membranes should have a high mechanical performance to attain a long service life (X. Wang et. al, Journal of Membrane Science 2021, 639, 119759).

[0010] Haemodialysis as extracorporeal blood cleaning technique is applied to remove metabolic waste products that accumulate in patients suffering from end-stage renal disease. In 2018 more than 300 million hollow-fiber dialyzers were used worldwide [C. Ronco, W. R. Clark, Haemodialysis membranes, Nature Reviews Nephrology 2018, 14, 394 - 410], In the recent years cellulosic polymers membrane materials were gradually substituted by synthetic polymers namely poly(aryl sulfone) polymers.

[0011] Upon dialyzing operation the non-specific adsorption of a plasma protein layer, known as secondary membrane or gel or protein cake, reduces effectively membrane permeability. This process known as fouling occurs immediately upon exposure of the dialyzer membrane to blood. For development of new polymeric membrane materials the reduction of their fouling behaviour represents an important material property to improve the life quality of hemodialysis patients.241410

[0012] 2

[0013] For the manufacturing process of poly(aryl sulfone) based membranes by non-solvent induced phase separation (NIPS) processing, hydrophilic water-soluble polymers such as polyvinylpyrrolidones and polyalkyleneoxides are frequently used as additives to adjust the viscosity of the polymer solution but also act as place holders for pores in the filtration layer of the hollow fiber membranes [S. Munari, Desalination 1988, 70, 265-275], In a subsequent post treatment step the nano porous filtration layer is formed by removal of the hydrophilic polymer from the poly(aryl sulfone) matrix [I. M. Wienk et.al, Journal Polymer Science: Part A: Polymer Chemistry 1995, 33, 49-54], Polar, aprotic solvents such as N-methyl-2-pyrrol idone (NMP), N,N-dimethylacetamide (DMAc) or N,N-dimethylformamide (DMF) are commonly used for the NIPS process.

[0014] Thus, there is a need for ultra / microfiltration (UF / MF) membranes that have an improved mechanical performance.

[0015] It was surprisingly found that addition of (TPU) in quantities up to 30 % by weight referring to the poly(ary I sulfone) membrane matrix polymer within the scope of the NIPS process produces UF / MF membranes with improved mechanical performance and at the same time keeping the membrane properties such as pure water permeance (PWP) and molecular-weight cut off (MWCO) as indicator for the filtration layer pore size comparable to the nonmodified poly(aryl sulfone) membranes.

[0016] Moreover, the addition of thermoplastic polyurethane (TPU) in quantities up to 25 wt% relative to the poly(arylene ether sulfone) matrix polymer improves the hydrophilicity of the resulting blend, as indicated by reduced water contact angles. Within the scope of the NIPS process, such blends yield membranes with improved anti-fouling properties while maintaining key performance parameters such as pure water permeance (PWP) and molecular weight cut-off (MWCO), which are indicative of albumin retention. Improved hydrophilicity is known to reduce protein adsorption, as proteins exhibit lower affinity to surfaces strongly bound to water molecules. Since protein adsorption is a key trigger for blood incompatibility, the membranes according to the present invention exhibit enhanced hemocompatibility. Compared to membranes based solely on PESU or PSU, the inventive membranes show lower contact angles and reduced protein adsorption. Furthermore, the glass transition temperatures (Tg) of the membranes exceed 150 °C, enabling steam sterilization of the dialyzer modules.

[0017] Brief description of the Figures

[0018] Figure 1 shows a SEM analysis of comparative example 3 top layer [TL], cross-section [CS] and bottom layer [BL] (magnification 1500 and 5000 x) of an ultrafiltration membrane based only on PESU.

[0019] Figure 2 shows SEM analysis of example 3 top layer [TL], cross-section [CS] and bottom layer [BL] (magnification 1500 and 5000 x) of an ultrafiltration membrane according to the present invention based on a PESU-TPU blend.241410

[0020] 3

[0021] Description of the invention

[0022] For the purposes of the present disclosure, abbreviations such as PSU, PPSU, PESU (PES) are in accordance with DIN EN ISO 1043-1:2001.

[0023] In the context of the present invention, the term “membrane” means a semipermeable structure acting as a selective barrier, allowing some particles, substances or chemicals to pass through, while retaining others. It is to be understood that for the disclosure of the present invention, the term “membrane” does equally address any membranes technically usable (“technical membrane”) and any membranes usable for dialysis (“dialyser membrane”), i.e. any embodiment relating to the “membrane (M)” equally relates to the corresponding technical membrane and dialyser membrane wherever technically reasonable.

[0024] As for the present invention, the number average molecular weight Mn of the polyol is determined by gel permeation chromatography based on DIN ISO 13885-1:2021-11 unless stated otherwise. The Mwof the TPU is determined by gel permeation chromatography based on DIN ISO 13885-2:2021-11 unless stated otherwise.

[0025] In the context of the present invention, the number average molecular weight (Mn) of the poly(arylene ether sulfones) is determined in accordance with ISO 1628-5 (1998), unless stated otherwise. The viscosity number (reduced viscosity, VN) correlates with the molecular weight of the polymer and can be measured based on ISO 1628-5 (1998) in a 1% by weight polymer solution in N-methylpyrrolidone. Thereby, the elution time (t) of a defined volume of the polymer solution in an Ubbelohde 1 C-capillary is related to the running time of the pure solvent (to) and normalized afterwards with the polymer concentration (c in g / ml) according to equation 1:

[0026]

[0027] The viscosity number is given in ml / g.

[0028] As for the present invention, the pure water permeability is determined as described in the Example section. In a first aspect, the present invention relates to a membrane (M) comprising a polymer matrix consisting of at least one polymer selected from the group consisting of poly(arylene ether sulfone) polymers (P1) and (P2), and a thermoplastic polyurethane (TPU); wherein (P1) and (P2) each comprises at least one structural repeating unit of the general formula (I)

[0029]

[0030] wherein the definitions of the symbols t, q, Q, T, Y, Ar and Ar1are as follows:241410

[0031] 4

[0032] t, q independently of one another 0, 1 , 2 or 3;

[0033] Q, T, Y independently of one another a chemical bond or a group selected from -O-, -S-, -SO2-, S=O, C=O, -N=N- and -CRaRb-, wherein Raand Rbindependently of one another are a hydrogen atom, (C 1-Ci2)alkyl, (C1-Ci2)alkoxy, (C3-Ci2)cycloalkyl or a (Ce-C jaryl group, and wherein at least one of Q, T, and Y is present and is -SO2-; and Ar and Ar1independently of one another (Ce-C jarylene; optionally wherein the at least one structural repeating unit of (P2) is different from the at least one structural repeating unit of (P1 ).

[0034] In one embodiment, at least one unit (I) comprises an arylene group which is substituted with at least one -SO2X group, wherein X is selected from the group consisting of Cl and O' combined with one cation equivalent, where the cation equivalent is H+, Li+, Na+, K+, Mg2+, Ca2+or NHY.

[0035] If Q, T or Y, among the abovementioned conditions, is a chemical bond, this is understood to mean that the adjacent group to the left and the adjacent group to the right are bonded directly to one another via a chemical bond. It will be readily appreciated that at least one of the groups consisting of Q, T and Y being -SO2- means that at least one group in formula (I) is -SO2-. Thus, when q is = 0, at least one of T and Y is -SO2-; when, for example, t is = 0, at least one of Q and Y is -SO2- and when q = 0 and t = 0 then Y is SO2.

[0036] In one certain embodiment, t and q are independently 0 or 1.

[0037] In another certain embodiment, Q, T, and Y in formula II are independently selected from a chemical bond, -O-, -SO2- and -CRaRb-, with the proviso that at least one of Q, T, and Y is present and is -SO2-.

[0038] Furthermore, it may be preferred, if Raand Rbare, independently of one another, hydrogen or (C i-C4)alkyl.

[0039] In -CRaRb-, Raand Rbare preferably independently selected from hydrogen, (C 1-Ci2)alkyl, (Ci-Ci2)alkoxy and (Ce-Ci8)aryl.

[0040] (Ci-Ci2)alkyl refers to linear or branched saturated hydrocarbon groups having from 1 to 12 carbon atoms. The following moieties are particularly encompassed: (Ci-Ce)alkyl, e.g. methyl, ethyl, n-propyl, isopropyl, n-butyl, secbutyl, 2- or 3-methylpentyl, as well as (Cz-C-^alkyl, e.g. unbranched heptyl, octyl, nonyl, decyl, undecyl, lauryl, and the singly branched or multibranched analogs thereof.

[0041] The term " Ci-Ci2-alkoxy" refers to a linear or branched alkyl group having 1 to 12 carbon atoms which is bonded via an oxygen, at any position in the alkyl group, e.g. methoxy, ethoxy, n-propoxy, 1 -methylethoxy, butoxy, 1-methyhpropoxy, 2-methylpropoxy or 1,1 -dimethylethoxy.

[0042] (C3-Ci2)cycloalkyl refers to monocyclic saturated hydrocarbon radicals having 3 to 12 carbon ring members and particularly comprises (Cs-Csjcycloalkyl, e.g. cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl,241410

[0043] 5

[0044] cyclooctyl, cyclopropylmethyl, cyclopropylethyl, cyclopropylpropyl, cyclobutylmethyl, cyclobutylethyl, cyclopentylethyl, -propyl, -butyl, -pentyl, -hexyl, cyclohexylmethyl, -dimethyl, and -trimethyl.

[0045] Ar and Ar1are independently of one another a (Ce-C J-arylene group. It may be preferred that, according to a specific embodiment, Ar1is an unsubstituted (C6-Ci2)arylene group.

[0046] It may be preferred that Ar and Ar1are independently selected from phenylene, bisphenylene and naphthylene groups, and from arylene groups that derive from anthracene, from phenanthrene, or from naphthacene. For examples, Ar and Ar1are independently selected from 1 ,2-phenylene, 1 ,3-phenylene, 1 ,4-phenylene,

[0047] 1.6-naphthylene, 1,7-naphthylene, 2,6-naphthylene and 2,7-naphthylene, 2,7-dihydroxynaphthylene and 4,4'-bisphenylene.

[0048] In particular, it may be preferred that Ar and Ar1are independently selected from phenylene and naphthylene groups, such as independently selected from 1 ,2-phenylene, 1 ,3-phenylene, 1 ,4-phenylene, 1 ,6-naphthylene, 1.7-naphthylene, 2,6-naphthylene and 2,7-naphthylene, more specifically independently selected from 1 ,4-phenylene, 1,3-phenylene and naphthylene. Furthermore, according to another embodiment of the present invention Ar and Ar1are independently selected from arylene groups that derive from anthracene, from phenanthrene, or from naphthacene. According to still a further embodiment, Ar and Ar1are independently selected from 2,7-dihydroxynaphthylene and 4,4'-bisphenylene.

[0049] Preferred sulfonated poly(arylene ether sulfone) polymers are those comprising at least one of the units la to Io as repeating structural units as defined and preferably defined herein, wherein at least one unit unit la to Io comprises an arylene group which is substituted with at least one -SO2X group, wherein X is selected from the group consisting of Cl and O' combined with one cation equivalent, where the cation equivalent is H+, Li+, Na+, K+, Mg2+, Ca2+or NH4+:

[0050] According to one embodiment, the sulfonated poly(arylene ether sulfone) polymer comprises at least one unit selected from the units la, Ig and Ik as repeating structural units, wherein at least one of said units comprises an arylene group which is substituted with at least one -SO2X group, wherein X is selected from the group consisting of Cl and O' combined with one cation equivalent, where the cation equivalent is H+, Li+, Na+, K+, Mg2+, Ca2+or NH4+:

[0051] According to one embodiment, the sulfonated poly(arylene ether sulfone) polymer comprises structural repeating units of formula la and is also termed sulfonated polysulfone (sPSU). Therein, unit la comprises an arylene group which is substituted with at least one -SO2X group, wherein X is selected from the group consisting of Cl and O’ combined with one cation equivalent, where the cation equivalent is H+, Li+, Na+, K+, Mg2+, Ca2+or NH4+:241410

[0052] 6

[0053] According to a further embodiment, the sulfonated poly(arylene ether sulfone) polymer comprises structural repeating units of formula Ig and is also termed sulfonated polyphenylene sulfone (sPPSU). Therein, unit Ig comprises an arylene group which is substituted with at least one -SO2X group, wherein X is selected from the group consisting of Cl and O' combined with one cation equivalent, where the cation equivalent is H+, Li+, Na+, K+, Mg2+, Ca2+or NHT.

[0054] According to still a further embodiment, the sulfonated poly(arylene ether sulfone) polymer comprises structural repeating units of formula Ik and is also termed sulfonated polyether sulfone (sPESU or sPES). Therein, unit Ik comprises an arylene group which is substituted with at least one -SO2X group, wherein X is selected from the group consisting of Cl and O' combined with one cation equivalent, where the cation equivalent is H+, Li+, Na+, K+, Mg2+, Ca2+or NHT.

[0055] In general, membranes are applied in various liquid and gaseous separations. The membrane may have various geometries such as flat sheet, spiral wound, pillows, tubular, single bore hollow fiber or multiple bore hollow fiber. For example, membranes (M) can be nanofiltration (NF) membranes, microfiltration (MF) membranes and ultrafiltration (UF) membranes. These membrane types are generally known in the art.

[0056] NF membranes are normally especially suitable for removing multivalent ions and large monovalent ions.

[0057] Typically, NF membranes function through a solution / diffusion or / and filtration -based mechanism. NF membranes are normally used in crossflow filtration processes. Nanofiltration membranes often comprise charged polymers comprising sulfonic acid groups, carboxylic acid groups and / or ammonium groups. MF membranes normally have an average pore diameter of 0.05 pm to 10 pm, preferably 1.0 pm to 5 pm, and they are normally suitable for removing particles with a particle size of 0.1 pm and above. Microfiltration can use a pressurized system, but it does not need to include pressure. MF membranes can be hollow fibers, capillaries, flat sheet, tubular, spiral wound, pillows, hollow fine fiber or track etched. They are porous and allow water, monovalent species (Na+, Cl -), dissolved organic matter, small colloids, and viruses to pass through but retain particles, sediment, algae or large bacteria.

[0058] UF membranes are normally suitable for removing suspended solid particles and solutes of high molecular weight, for example above 100,000 Da. UF membranes may be particularly suitable for removing bacteria and viruses. Usually, UF membranes have an average pore diameter of 0.5 nm to 50 nm, preferably 1 to 40 nm, more preferably 5 to 20 nm.

[0059] The inventive membrane (M) can be used in any processes known to the skilled person in which membranes are used.241410

[0060] 7

[0061] The membrane (M) may be a porous membrane. A porous membrane typically comprises pores, wherein the pores usually have a diameter in the range of from 1 nm to 10000 nm, preferably in the range of from 2 to 500 nm and particularly preferably in the of range from 5 to 250 nm determined via filtration experiments using a solution containing different PEG'S covering a molecular weight from 300 to 1000000 g / mol. By comparing the GPC-traces of the feed and the filtrate, the retention of the membrane for each molecular weight can be determined. The molecular weight, where the membrane shows a 90% retention is considered as the molecular weight cutoff (MWCO) for this membrane under the given conditions. Using the known correlation between the Stoke diameters of PEG and their molecular weights, the mean pore size of a membrane can be determined. Details about this method are given in the literature (Chung, J. Membr. Sci. 531 (2017) 27-37). A porous membrane may typically be obtained if the membrane is prepared via a phase inversion process.

[0062] In one embodiment of the present invention, the membrane (M) is a dense membrane. In particular, if the membrane is a dense membrane, it is particularly suitable for gas separation.

[0063] The membrane (M) can have any thickness. For example, the thickness of the membrane may be in the range from 2 to 350 pm, preferably in the range from 3 to 200 pm and most preferably in the range from 5 to 100 pm.

[0064] According to one embodiment of the present invention the membrane (M) of the invention is an asymmetric membrane. In a further embodiment, the membrane is porous.

[0065] The membrane (M) of the invention is particularly suitable for nanofiltration, microfiltration and / or ultrafiltration, particularly if the membrane is a porous membrane.

[0066] Therefore, according to one embodiment of the invention, the membrane (M) is a nanofiltration, ultrafiltration (UF) and / or microfiltration membrane. Typical nanofiltration, ultrafiltration and microfiltration processes are known to the skilled person.

[0067] According to one particular embodiment, the inventive membrane is an ultrafiltration membrane.

[0068] In a further particular embodiment, the inventive membranes (M) are UF membranes that are spiral wound membranes, pillow membranes or flat sheet membranes. In another embodiment the inventive membranes (M) are UF membranes that are tubular membranes.

[0069] In still another embodiment thereof, the membrane (M) is a hollow fiber membrane, wherein it may be a single bore hollow fiber or multiple bore hollow fiber membrane. In a hollow fiber membrane, a semipermeable barrier is in the form of a hollow fiber.Multiple channel membranes, also referred to as multi bore membranes, comprise more than one longitudinal channel, also referred to as “channel” or “bore”.

[0070] The number of channels is typically 2 to 19. In one embodiment, the multiple bore hollow fiber membrane comprises two or three channels. In another embodiment, the multiple bore hollow fiber membrane comprises 5 to 9 channels. In one specific embodiment, the multiple bore hollow fiber membrane comprises seven channels. In yet another embodiment, the multiple bore hollow fiber membrane comprises 20 to 100 channels.

[0071] The shape of the bore or bores may vary. Normally, the membranes according to the invention have an essentially circular, ellipsoid or rectangular diameter. Preferably, membranes according to the invention are essentially circular, i.e. the bores have an essentially circular diameter.

[0072] In another embodiment, such bores have an essentially ellipsoid diameter. In yet another embodiment, channels have an essentially rectangular diameter. In some cases, the actual form of such channels may deviate from the idealized circular, ellipsoid or rectangular form.

[0073] Normally, such channels have an outer diameter (for essentially circular diameters), an outer smaller diameter (for essentially ellipsoid diameters) or an outer smaller feed size (for essentially rectangular diameters) of 0.05 mm to 3 mm, preferably 0.5 to 2 mm, more preferably 0.9 to 1.5 mm. In another preferred embodiment, such channels have an outer diameter (for essentially circular diameters), an outer smaller diameter (for essentially ellipsoid diameters) or an outer smaller feed size (for essentially rectangular diameters) in the range from 0.2 to 0.9 mm.

[0074] According to the invention, in one preferred embodiment, the hollow fiber membranes have an outer diameter (for essentially circular diameters), an outer smaller diameter (for essentially ellipsoid diameters) or an outer smaller feed size (for essentially rectangular diameters) of 2 to 10 mm, preferably 3 to 8 mm, more preferably 4 to 6 mm. In another preferred embodiment according to the invention, the hollow fiber membranes have an outer diameter (for essentially circular diameters), an outer smaller diameter (for essentially ellipsoid diameters) or an outer smaller feed size (for essentially rectangular diameters) of 2 to 4 mm.

[0075] The hollow fiber membrane can have any thickness. For example, the thickness of the membrane is in the range from 20 to 150 pi m, preferably in the range from 20 to 100 pi m and most preferably in the range from 30 to 60 pirn. This can be particularly suitable for dialysis membranes.

[0076] If multi-bore hollow fiber membranes contain channels with an essentially rectangular shape, these channels can be arranged in a row. If the channels in a multi-bore hollow fiber membrane have essentially circular shape, these channels are preferably arranged such that a central channel is surrounded by the other channels. In onepreferred embodiment, a membrane comprises one central channel and for example four, six or 18 further channels arranged cyclically around the central channel. The wall thickness in such multiple channel membranes is normally from 0.02 to 1 mm at the thinnest position, preferably 30 to 500 pm, more preferably 100 to 300 pm.

[0077] In one embodiment, the at least one structural repeating unit for (P1) and (P2), respectively, is selected from the following units la to Is:

[0078]

[0079] wherein x is from 0.05 to 1 and n is 1 ;wherein x is from 0.05 to 1 and n is 1.

[0080] In another embodiment, in the inventive membrane (M), the at least one repeating structural unit for (P1) and (P2), respectively, is preferably selected from the units la to Io and Is.

[0081] In yet another embodiment, in the inventive membrane (M), the at least one repeating structural unit for (P1) and (P2), respectively, is preferably selected from the units la to Io.

[0082] In yet another embodiment, in the inventive membrane (M), the at least one repeating structural unit for (P1) and (P2), respectively, is preferably selected from the units la, Ig, Ik, Ip, and Is, more specifically selected from the units la, Ig, Ik, and Is.

[0083] In yet another embodiment of the inventive membrane (M), the at least one repeating structural unit for (P1) and (P2), respectively, is preferably selected from the units la, Ig and Ik.

[0084] In a certain embodiment, (P1) comprises the unit la as structural repeating unit and (P2) comprises the unit Ik. In another certain embodiment, (P1) comprises the unit Ig as structural repeat-ing unit and (P2) comprises the unit Ik.

[0085] In another certain embodiment of the invention, (P1) comprises the unit la as structural repeating unit and (P2) comprises the unit Ip.In another certain embodiment, (P1) comprises the unit Ig as structural repeat-ing unit and (P2) comprises the unit Ip.

[0086] In another certain embodiment, (P1) comprises the unit Ik as structural repeat-ing unit and (P2) comprises the unit Ip.

[0087] In another certain embodiment of the invention, (P1) comprises the unit la as structural repeating unit and (P2) comprises the unit Is.

[0088] In another certain embodiment, (P1) comprises the unit Ig as structural repeating unit and (P2) comprises the unit Is.

[0089] In another certain embodiment, (P1) comprises the unit Ik as structural repeating unit and (P2) comprises the unit Is.

[0090] In one embodiment, the weight-average molar masses Mn of the polymer matrix is preferably in the range of from 19.000 to 164.000 g / mol, more preferably in the range from 23.000 to 148.000 g / mol and particularly preferably in the range from 27.000 to 136.000 g / mol, determined by means of gel permeation chromatography in dimethylacetamide as solvent against narrowly distributed polymethyl methacrylate as standard. More specifically, the Mw is from 19.000 to 102.000 g / mol, more specifically from 21.000 to 96.000 g / mol, in particular from 22.000 to 93000 g / mol, particularly preferably from 24.000 to 86.000 g / mol.

[0091] The dialyser membrane (M) has a certain weight average molecular weight cut-off of the membranes (MWCO). Molecular weight of the PEG standard of the lowest weight-average molecular weight (Mw) which is withhold to at least 90% by the membrane. It is usually given in kilo-Daltons (kDa).

[0092] Thus, according to any embodiment, the MWCO of the dialyser membrane (M) is at least 5 kDa. In another embodiment, the MWCO of the dialyser membrane (M) is at least 10 kDa. In yet another embodiment, the MWCO of the dialyser membrane (M) is at least 15 kDa. In yet another embodiment, the MWCO of the dialyser membrane (M) is at least 21 kDa. In yet another embodiment, the MWCO of the dialyser membrane (M) is at least 33 kDa. In yet another embodiment, the MWCO of the dialyser membrane (M) is at least 42 kDa. In yet another embodiment, the MWCO of the dialyser membrane (M) is at least 56 kDa. In yet another embodiment, the MWCO of the dialyser membrane (M) is at least 61 kDa. In yet another embodiment, the MWCO of the dialyser membrane (M) is at least 70 kDa. In yet another embodiment, the MWCO of the dialyser membrane (M) is at least 82 kDa.According to any embodiment, the MWCO of the membrane (M) isup to 95 kDa. In another embodiment, the MWCO of the dialyser membrane (M) is up to 86 kDa. In yet another embodiment, the MWCO of the dialyser membrane (M) is up to 77 kDa. In yet another embodiment, the MWCO of the dialyser membrane (M) is up to 70 kDa. In yet another embodiment, the MWCO of the dialyser membrane (M) is up to 65 kDa. In yet another embodiment, the MWCO of the dialyser membrane (M) is up to 59 kDa. In yet another embodiment, the MWCO of the dialyser membrane (M) is up to 52 kDa. In yet another embodiment, the MWCO of the dialyser membrane (M) is up to 44 kDa. In yet another embodiment, the MWCO of the dialyser membrane (M) is up to 37 kDa. In yet another embodiment, the MWCO of the dialyser membrane (M) is up to 31 kDa. In yet another embodiment, the MWCO of the dialyser membrane (M) is up to 25 kDa.

[0093] The MWCO is estimated as described in the Examples herein below.

[0094] In one embodiment, the viscosity number (V.N.) of the polymer matrix is from 60 to 120 ml / g. In another embodiment, the V.N. of the polymer matrix is from 66 to 112 ml / g. In yet another embodiment, the V.N. of the polymer matrix is from 71 to 112 ml / g.

[0095] It is preferable that the poly(arylene ether sulfone) polymers (P1 ) and / or (P2) have either halogen end groups, in particular chlorine end groups, or etherified end groups, in particular alkyl ether end groups, these being obtainable via reaction of the OH or, respectively, phenolate end groups with suitable etherify I ng agents.

[0096] Examples of suitable etherifying agents are monofunctional alkyl or aryl halide, e.g. C1 C6 -alkyl chloride, C1 C6-alkyl bromide, or C1 C6-alkyl iodide, preferably methyl chloride, or benzyl chloride, benzyl bromide, or benzyl iodide, or a mixture thereof. For the purposes of the polyarylene(ether)sulfones of polymers (P1) and / or (P2) preferred end groups are halogen, in particular chlorine, alkoxy, in particular methoxy, aryloxy, in particular phenoxy, or benzyloxy.

[0097] The combined % by weight of the poly(arylene ether sulfone) polymers (P1) and (P2) comprised in the inventive membrane (M) is preferably at least 50 % by weight, more preferably at least 70 % by weight and most preferably at least 90 % by weight, based on the total weight of the membrane (M). In a further preferred embodiment, the membrane (M) consists essentially of the poly(arylene ether sulfone) polymers (P1) and (P2). “Consisting essentially of’ means that the membrane (M) comprises more than 95% by weight, preferably more than 97.5% by weight and most preferably more than 98% by weight of the poly(arylene ether sulfone) polymers (P1) and (P2), as combined % by weight of (P1) and (P2) and based on the total weight of the membrane.

[0098] In one embodiment, the combined amount of poly(arylene ether sulfone) polymers (P1) and (P2), as defined and preferably defined herein, in the inventive membrane (M) is 40 to 98% by weight, more specifically 45 to 97% by weight, even more specifically 50 to 96% by weight, even more specifically 60 to 95% by weight, based on the total weight of the membrane (M).In another embodiment, the combined amount of poly(arylene ether sulfone) polymers (P1) and (P2), as defined and preferably defined herein, in the inventive membrane (M) is up to 98% by weight. In yet another embodiment, the combined amount of poly(arylene ether sulfone) polymers (P1) and (P2) is up to 97% by weight. In yet another embodiment, the combined amount of poly(arylene ether sulfone) polymers (P1 ) and (P2) is up to 96% by weight. In yet another embodiment, the combined amount of poly(arylene ether sulfone) polymers (P1) and (P2) is up to 95% by weight. In yet another embodiment, the combined amount of poly(arylene ether sulfone) polymers (P1) and (P2) is up to 94% by weight. In yet another embodiment, the combined amount of poly(arylene ether sulfone) polymers (P1) and (P2) is up to 93% by weight. In yet another embodiment, the combined amount of poly(arylene ether sulfone) polymers (P1) and (P2) is up to 92% by weight. In yet another embodiment, the combined amount of poly(arylene ether sulfone) polymers (P1) and (P2) is up to 90% by weight. In yet another embodiment, the combined amount of poly(arylene ether sulfone) polymers (P1) and (P2) is up to 87% by weight. In yet another embodiment, the combined amount of poly(arylene ether sulfone) polymers (P1) and (P2) is up to 85% by weight. In yet another embodiment, the combined amount of poly(arylene ether sulfone) polymers (P1) and (P2) is up to 83% by weight. In yet another embodiment, the combined amount of poly(arylene ether sulfone) polymers (P1) and (P2) is up to 81% by weight. In yet another embodiment, the combined amount of poly(arylene ether sulfone) polymers (P1) and (P2) is up to 79% by weight. In yet another embodiment, the combined amount of poly(arylene ether sulfone) polymers (P1) and (P2) is up to 78% by weight. In yet another embodiment, the combined amount of poly(arylene ether sulfone) polymers (P1) and (P2) is up to 76% by weight. In yet another embodiment, the combined amount of poly(arylene ether sulfone) polymers (P1) and (P2) is up to 75% by weight. In yet another embodiment, the combined amount of poly(arylene ether sulfone) polymers (P1 ) and (P2) is up to 73% by weight. In yet another embodiment, the combined amount of poly(arylene ether sulfone) polymers (P1) and (P2) is up to 70% by weight.

[0099] In the inventive membrane (M), the ratio of poly(arylene ether sulfone) polymers (P1) to (P2), as defined and preferably defined herein, can be any possible weight ratio, such as for example 1 :10 to 10:1, in particular 1 :9 to 9:1, more particularly 1 :8 to 8:1, even more particularly 1 :7 to 7:1. According to a certain embodiments, the ratio can be 1 :6 to 6:1 or 1:5 to 5:1, in particular 1:4 to 4:1, more particularly 1 :3 to 3:1, even more particularly 1 :2 to 2:1. According to a particular embodiment of the present invention, (P1) and (P2) may be present in equal or nearly equal amounts (1:1). Nearly equal amounts” within this context means that the difference in amounts of (P1) and (P2) is only in a neglectable range.

[0100] The membrane (M) comprises at least one thermoplastic polyurethane (TPU). In the present invention, the thermoplastic polyurethane (TPU) is the reaction product of at least the following building components, diisocyanate, polyol and a chain extender.According to the present invention, the thermoplastic polyurethane (TPU) is a segmented block copolymer comprising alternating soft and hard phases. The soft phase is formed by long-chain isocyanate-reactive group, in particular polyols, which impart flexibility and elasticity to the polymer. The hard phase is formed by the reaction of diisocyanates with short-chain diols (chain extenders), providing mechanical strength and thermal stability. In one embodiment, the TPU is an elastomer, i.e. a polymeric material that exhibits reversible deformation under mechanical stress and recovers its original shape upon release of the stress. It should be noted that the term “long chain” refers to extended sequences of carbon atoms, comprising 6 or more carbon atoms in their backbone. These carbon atoms may be linked through ether functional groups or other heteroatoms, with the total number of carbon atoms summing to at least 6.

[0101] These building components may be reacted in the presence of a catalyst to form the related thermoplastic polyurethane (TPU). The catalyst may either be a single catalyst or is a mixture of several catalysts. The catalysts preferably accelerate the reaction between the NCO groups of the isocyanates and the hydroxyl groups of the polyol and of the chain extender. Suitable catalysts are generally known in the art and may be selected from the group comprising a tertiary amine and an organic metal compound or any mixture thereof. The catalyst may be used in an amount of from 0.0001 to 0.1 part by weight per 100 parts by weight of the polyol.

[0102] In one embodiment, the soft phase comprises at least one polyol selected from the group consisting of polyether polyols, polyester polyols, and polycarbonate polyols. In one embodiment, the polyether polyol is selected from polyethylene glycol (PEG), polypropylene glycol (PPG), poly(tetramethylene ether glycol) (PTMG), poly(oxytetramethylene) (PTMO), poly(oxybutylene) glycol, and block copolymers of PEG and PPG.

[0103] In one embodiment, the polyester polyol is selected from poly(butylene adipate) glycol, poly(caprolactone) diol, poly(lactic acid) polyol, polyethylene succinate) glycol, poly(hexamethylene adipate) glycol, and polypropylene glycol) adipate.

[0104] In one embodiment, the polycarbonate polyol is selected from polycarbonate diols derived from bisphenol A, diphenyl carbonate, dimethyl carbonate, ethylene glycol, propylene glycol, or cyclohexane dimethanol.

[0105] In one embodiment, the hard phase is formed from diphenylmethane-4,4'-diisocyanate (MDI) and 1 ,4-butanediol.

[0106] According to one embodiment, the thermoplastic polyurethane (TPU) comprises at least one polyol selected from polyethylene glycol (PEG) polyols. According to another embodiment, the TPU comprises at least one polyol comprising at least one polyethylene glycol (PEG) block. These polyols contribute to enhanced hydrophilicity of the TPU, which may improve the anti-fouling properties and hemocompatibility of the resulting membrane.241410

[0107] 16

[0108] According to any embodiment, the TPU does not comprise 1,6-hexanediol. The absence of 1 ,6-hexanediol contributes to improved phase separation between the hard and soft segments of the TPU, which results in enhanced mechanical properties of the resulting membrane.

[0109] According to any embodiment, the soft phase is not consisting of polytetrahydrofuran (polyTHF). In a further embodiment, the soft phase comprises polytetrahydrofuran and at least one more polyol.

[0110] Preference is given in the invention to the production of thermoplastic polyurethanes where the weight-average molar mass (Mw) of the thermoplastic polyurethane is at least 60.000 g / mol, preferably at least 80.000 g / mol and in particular greater than 100.000 g / mol. The upper limit of the weight-average molar mass of the thermoplastic polyurethanes is very generally determined by processability, and also by the desired property profile. The number-average molar mass of the thermoplastic polyurethanes is preferably from 80.000 to 300000 g / mol.

[0111] The preparation of the thermoplastic polyurethane (TPU) can be carried out according to the known processes as a batch operation or as a continuous operation, for example using reactive extruders or the belt process by the one shot or the prepolymer process, preferably by the one shot process. In these processes, the reactant components can be mixed in succession or at the same time, and the reaction ensues immediately. In the extruder process, the structural components and also optionally chain extender, catalyst and / or added substances are introduced into the extruder individually or as a mixture, reacted at temperatures of 100 to 280 °C and preferably 140 to 250 °C, for example, and the thermoplastic polyurethane (TPU) obtained is extruded, cooled down and pelletized.

[0112] In one embodiment, the thermoplastic polyurethane (TPU) is the reaction product of at least one isocyanate, at least one isocyanate reactive group and at least one chain extender.

[0113] Thus, in a certain embodiment, the isocyanate reactive group is a polyol. Preferably, the polyol is a diol. It is to be understood that for the disclosure of the present invention, the term “polyol” can be equally substituted by the term “diol”, i.e. any embodiment relating to a polyol equally relates to the corresponding diol.

[0114] In another embodiment the isocyanate is selected from the group consisting of aliphatic and aromatic diisocyanates, and any combination thereof.

[0115] Organic isocyanates that can be used are aliphatic, cycloaliphatic, araliphatic and / or aromatic isocyanates.

[0116] Aliphatic diisocyanates used are customary aliphatic and / or cycloaliphatic diisocyanates, for example tri-, tetra-, penta-, hexa-, hepta- and / or octamethylene diisocyanate, 2-methylpentamethylene 1 ,5-diisocyanate, 2-ethyltetramethylene 1 ,4-diisocyanate, hexamethylene 1 ,6-diisocyanate (HDI), pentamethylene 1 ,5-diisocyanate,241410

[0117] 17

[0118] butylene 1 ,4-diisocyanate, trimethyl hexamethylene 1 ,6-diisocyanate, 1 -isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (isophorone diisocyanate, IPDI), 1,4- and / or 1,3-bis(isocyanatomethyl)cyclohexane (HXDI), cyclohexane 1 ,4-diisocyanate, 1 -methylcyclohexane 2,4- and / or 2, 6-diisocyanate, methylenedicyclohexyl 4,4'-, 2,4'- and / or 2, 2'-diisocyanate (H12MDI).

[0119] Suitable aromatic diisocyanates are in particular naphthylene 1 ,5-diisocyanate (NDI), tolylene 2,4- and / or 2,6-diisocyanate (TDI), 3,3’-dimethyl-4,4‘-diisocyanatobiphenyl (TODI), p phenylene diisocyanate (PDI), diphenylethane 4,4‘-diisoyanate (EDI), methylenediphenyl diisocyanate (MDI), where the term MDI means diphenylmethane 2,2’, 2,4’- and / or 4, 4’-diisocyanate, 3, 3’ -dimethyldiphenyl diisocyanate, 1 ,2-diphenylethane diisocyanate and / or phenylene diisocyanate

[0120] Mixtures can in principle also be used. Examples of mixtures are mixtures comprising at least a further methylenediphenyl diisocyanate alongside methylenediphenyl 4,4’-diisocyanate. The term “methylenediphenyl diisocyanate” here means diphenylmethane 2,2’-, 2,4’- and / or 4,4’-diisocyanate or a mixture of two or three isomers. It is therefore possible to use by way of example the following as further isocyanate: diphenylmethane 2,2’- or 2,4’-diisocyanate or a mixture of two or three isomers. In this embodiment, the polyisocyanate composition can also comprise other abovementioned polyisocyanates.

[0121] Other examples of mixtures are polyisocyanate compositions comprising 4,4‘-MDI and 2,4‘-MDI, or 4,4‘-MDI and 3,3‘-dimethyl-4,4‘-diisocyanatobiphenyl (TODI) or 4,4‘-MDI and H12MDI (4,4'-methylene dicyclohexyl diisocyanate) or 4,4‘-MDI and TDI; or 4,4‘-MDI and 1 ,5-naphthylene diisocyanate (NDI).

[0122] In accordance with the invention, three or more isocyanates may also be used. The polyisocyanate composition commonly comprises 4,4’-MDI in an amount of from 2 to 50%, based on the entire polyisocyanate composition, and the further isocyanate in an amount of from 3 to 20%, based on the entire polyisocyanate composition.

[0123] Crosslinkers can be used as well, moreover, examples being the aforesaid higher-functionality polyisocyanates or polyols or else other higher-functionality molecules having a plurality of isocyanate-reactive functional groups. It is also possible within the realm of the present invention for the products to be crosslinked by an excess of the isocyanate groups used, in relation to the hydroxyl groups. Examples of higher-functionality isocyanates are triisocyanates, e.g. triphenylmethane 4,4',4"-triisocyanate, and also isocyan urates, and also the cyanurates of the aforementioned diisocyanates, and the oligomers obtainable by partial reaction of diisocyanates with water, for example the biurets of the aforementioned diisocyanates, and also oligomers obtainable by controlled reaction of semiblocked diisocyanates with polyols having an average of more than two and preferably three or more hydroxyl groups.241410

[0124] 18

[0125] The amount of crosslinkers here, i.e. of higher-functionality isocyanates and higher-functionality polyols, ought not to exceed 3% by weight, preferably 1 % by weight, based on the overall mixture of components.

[0126] The polyisocyanate composition may also comprise one or more solvents. Suitable solvents are known to those skilled in the art. Suitable examples are nonreactive solvents such as ethyl acetate, methyl ethyl ketone and hydrocarbons.

[0127] In another embodiment, the isocyanate reactive group is an amine, a mercapto compound or any mixture thereof.

[0128] In a further embodiment, the polyol is selected from the group consisting of polyetherpolyols, polycarbonate polyols, polyesterpolyols and any combination thereof.

[0129] In one more embodiment, the polyol comprises a polyether polyol. Polyetherpolyol has the advantage that it is more stable against hydrolysis and thus will be applied in applications where this is a requirement, such as dialysis. Polyether polyols are obtained by known methods, such as but not limited to, reaction between at least one starter molecule, such as ethylene glycol, propylene glycol or butylene glycol, and optionally alkylene oxide such as ethylene oxide, propylene oxide, mixtures of ethylene oxide and propylene oxide or derive

[0130] from tetrahydrofuran.

[0131] Optionally, the polyether diol is based on ethylene oxide, propylene oxide and / or butyleneoxide unites, or a mixture thereof. In a certain embodiment, the polyether polyol comprises polytetrahydrofuran (PTHF), poly 1,3-propanediol (PPG) polyethylene glycol (PEG), Pluronic® F-127 or is a mixture thereof. Pluronic® F-127 is the known commercial name for a non-ionic copolymer identified by CAS. No. 9003-11-6.

[0132] In a specific embodiment the polyether diol is PTHF. In another specific embodiment the polyether diol is poly PEG. In another specific embodiment the polyether diol is PPG. In another specific embodiment the polyether diol is PEG. In another specific embodiment the polyether diol is Pluronic® F-127.

[0133] In a further embodiment, the polyether polyol has a number average molecular weight (Mn) of at least 100 g / mol. The number average molecular weight (Mn) is determined by gel permeation chromatography according to DIN ISO 13885-1:2021-11.

[0134] In yet a further embodiment, the polyether polyol has a number average molecular weight (Mn) of at least 200 g / mol. In yet a further embodiment, the polyether polyol has a number average molecular weight (Mn) of at least 300 g / mol. In yet a further embodiment, the polyether polyol has a number average molecular weight (Mn) of at least 400 g / mol. In yet a further embodiment, the polyether polyol has a number average molecular weight (Mn) of at least 500 g / mol. In yet a further embodiment, the polyether polyol has a has a number average molecular241410

[0135] 19

[0136] weight (Mn) of at least 1000 g / mol. In yet a further embodiment, the polyether polyol has a number average molecular weight (Mn) of at least 1200 g / mol. In yet a further embodiment, the polyether polyol has a number average molecular weight (Mn) of at least 1500 g / mol. In yet a further embodiment, the polyether polyol has a number average molecular weight (Mn) of at least 2000 g / mol. In yet a further embodiment, the polyether polyol has a number average molecular weight (Mn) of at least 2500 g / mol. In yet a further embodiment, the polyether polyol has a number average molecular weight (Mn) of at least 3000 g / mol. In yet a further embodiment, the polyether polyol has a number average molecular weight (Mn) of at least 3500 g / mol. In yet a further embodiment, the polyether polyol has a number average molecular weight (Mn) of at least 4000 g / mol.

[0137] In a certain embodiment, the polyether polyol has a number average molecular weight (Mn) between 500 and 16000 g / mol. In another certain embodiment, the polyether polyol has a number average molecular weight (Mn) between 500 and 14000 g / mol. In another certain embodiment, the polyether polyol has a number average molecular weight (Mn) between 500 and 13000 g / mol. In another certain embodiment, the polyether polyol has a number average molecular weight (Mn) between 500 and 12000 g / mol. In another certain embodiment, the polyether polyol has a number average molecular weight (Mn) between 500 and 11000 g / mol. In another certain embodiment, the polyether polyol has a number average molecular weight (Mn) between 500 and 10000 g / mol. In another certain embodiment, the polyether polyol has a has a number average molecular weight (Mn) between 500 and 9000 g / mol. In another certain embodiment, the polyether polyol has a number average molecular weight (Mn) between 500 and 8000 g / mol. In another certain embodiment, the polyether polyol has a number average molecular weight (Mn) between 500 and 7000 g / mol. In another certain embodiment, the polyether polyol has a has a number average molecular weight (Mn) between 500 and 6000 g / mol. In another certain embodiment, the polyether polyol has a number average molecular weight (Mn) between 500 and 5000 g / mol. In another certain embodiment, the polyether polyol has a number average molecular weight (Mn) between 500 and 4600 g / mol. In another certain embodiment, the polyether polyol has a number average molecular weight (Mn) between 500 and 4100 g / mol. In another certain embodiment, the polyether polyol has a number average molecular weight (Mn) between 500 and 3700 g / mol. In another certain embodiment, the polyether polyol has a number average molecular weight (Mn) between 500 and 3300 g / mol. In another certain embodiment, the polyether polyol has a number average molecular weight (Mn) between 500 and 3000 g / mol. In another certain embodiment, the polyether polyol has a number average molecular weight (Mn) between 500 and 2800 g / mol. In another certain embodiment, the polyether polyol has a number average molecular weight (Mn) between 500 and 2500 g / mol.

[0138] It is to be understood that the present invention may also utilize a mixture of two or more polyether polyols.

[0139] In one more embodiment, the polyol comprises a polycarbonate polyol. Polycarbonate polyols have good permeability for microwave, very low dirt uptake and show good flame retardancy.241410

[0140] 20

[0141] In another embodiment, polycarbonate polyols are polycarbonate diols based on alkane diols. The production of polycarbonate diols can be carried out by polycondensation of phosgene with diols or by ring -opening polymerization of cyclic carbonates. As a preferred alternative to phosgene synthesis, a transesterification with carbonic acid diesters is applied.

[0142] In a further embodiment, polycarbonate diols are OH-difunctional polycarbonate diols. In yet a further embodiment, polycarbonate diols are OH-difunctional aliphatic polycarbonate diols. In a certain embodiment, polycarbonate diols are based on butanediol, pentanediol or hexanediol.

[0143] In another certain embodiment, polycarbonate diols are based on 1 ,4-butane-diol, 1 ,5-pentanediol, 1,6-mexanediol, 3-methylpentane-(1 ,5)-diol or any mixture thereof. In another certain embodiment, polycarbonate diols are based on 1 ,4-butanediol, 1 ,5-pentanediol, 1,6-hexanediol or any mixture thereof. In another certain embodiment, polycarbonate diols are based on butanediol and hexanediol, polycarbonate diols based on pentanediol and hexanediol, polycarbonate diols based on hexanediol or mixtures thereof.

[0144] Preferably, the polycarbonate diol has a number average molecular weight (Mn) in the range from 500 to 4.000 g / mol, preferably in the range from 680 g / mol to 3.000 g / mol, preferred in the range from 810 g / mol to 2.470 g / mol, more preferred the number average molecular weight (Mn) is between 1 .690 g / mol and 2.180 g / mol or between 790 g / mol and 1.220 g / mol.

[0145] In one more embodiment, the polyol comprises a polyester polyol. Polyester polyols are preferred in applications where biodegradability is required.

[0146] In another embodiment, the polyester is selected from the group consisting of reaction product of polyhydric alcohol, polymerization product of lactone and polymerization product of dicarboxylic acids with polyhydric alcohols. The term "lactone" refers to cyclic esters of hydroxycarboxylic acids. Such polyester polyols include hydroxyl-terminated reaction products of polyhydric alcohols, polyester polyols obtained as the polymerization product of lactone, e.g. caprolactone, in conjunction with a polyol, and polyester polyols obtained by the polymerization of a di-carboxylic acid, e.g. adipic acid, with a polyhydric alcohol. Preferred polyester polyols include polymerization product of lactone or polycaprolactone and the ones obtained by the polymerization of a di-carboxylic acid with a polyhydric alcohol.

[0147] In a further embodiment, the polyester polyol is obtained by polymerizing a dicarboxylic acid with a polyhydric alcohol.

[0148] In a certain embodiment, the dicarboxylic acid is at least one of C4 to C12 dicarboxylic acid. In another certain embodiment, the C4 to C12 dicarboxylic acid is selected from the group consisting of an aliphatic dicarboxylic acid, preferably selected from succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid and sebacic acid or241410

[0149] 21

[0150] any mixture thereof and an aromatic dicarboxylic acid, preferably selected from phthalic acid, isophthalic acid and terephthalic acid or any mixture thereof. In a specific embodiment, the dicarboxylic acid is selected from the group consisting of succinic acid, glutaric acid, adipic acid, suberic acid, phthalic acid, isophthalic acid and terephthalic acid, or any mixture thereof. Preferably, the dicarboxylic acid it is selected from the group consisting of adipic acid, suberic acid and phthalic acid, or any mixture thereof.

[0151] In a certain embodiment, the polyhydric alcohol is at least one C2 to C14 polyhydric alcohol. Suitable polyhydric alcohols include, for example, polyhydric aliphatic alcohols, for example aliphatic alcohols having 2, 3, 4 or more OH groups, for example 2 or 3 OH groups. Preferably the polyhydric alcohol is a diol. It is to be understood that the diol may be combined with any of the embodiments used herein to describe a polyhydric alcohol. In other words, the term “polyhydric alcohol” may be substituted by the term “diol” in any embodiment of the present invention.

[0152] In another certain embodiment, the polyhydric alcohol is at least one C2 to C14 polyhydric alcohol. In another certain embodiment, the polyhydric alcohol is at least one C2 to C12 alcohol. In another certain embodiment, the polyhydric alcohol is at least one C2 to Ca alcohol. In another certain embodiment, the polyhydric alcohol is at least one C2 to Ce alcohol.

[0153] In another certain embodiment, the polyhydric alcohol is selected from the group consisting of from the group consisting of ethylene glycol, diethylene glycol, 1 ,4-butanediol, 1 ,5-pentanediol, 1 ,6-hexanediol, 1 ,10-decanediol, 2,2-dimethyl-propane-1 ,3-diol, 1 ,3-propanediol, 2-methyl-1 ,3-propanediol and di-propylene glycol, or is a mixture thereof. More preferably, the diol is selected from the group consisting of ethylene glycol, diethylene glycol, 1 ,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,10-decanediol or a mixture thereof. Most preferably, it is selected from the group consisting of 1 ,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,10-decanediol or any mixture thereof.

[0154] In another certain embodiment, the polyhydric alcohol is a polyether polyol as described herein above with the proviso that the number-average molar mass (Mn) of the polyester polyol is up to 6.000 g / mol, preferably between 500 and 3500 g / mol. It is to be understood that if the polyhydric alcohol is a polyether polyol said polyether polyol comprises 2, 3, 4 or more OH groups, preferably the polyether polyol is a diol.

[0155] It is to be understood that the present invention may also utilize a mixture of two or more polyhydric alcohols.

[0156] It is also possible for the purposes of the present invention to employ a polyhydric alcohol at least partly obtained from renewable raw materials. The polyhydric alcohol in question may be partly or wholly obtained from renewable raw materials. It is also possible to employ a mixture of two or more polyhydric alcohols in the present invention. Where a mixture of two or more polyhydric alcohols is employed, one or more of the polyhydricalcohols employed may be at least partly obtained from renewable raw materials. The same applies for the diacids, the polyether polyols and the polycarbonate polyols as described herein above.

[0157] Thus, in one embodiment, the diacid, polyol and polyhydric alcohol are non-fossil based.

[0158] In one more embodiment, a chain extender is used in the synthesis of the thermoplastic polyurethane (TPU). In another embodiment the chain extender comprises at least one aliphatic, araliphatic, aromatic and / or cycloaliphatic compound. In a further embodiment, the chain extender has a number average molecular weight (Mn) of 50 to 500 g / mol. In yet another embodiment, the chain extender has 2 groups reactive with isocyanate. These groups are also referred to as functional groups. In yet another embodiment, the chain extender is either a single chain extender or a mixture of at least two chain extenders.

[0159] In yet another embodiment, the chain extender is a difunctional compound, preferred examples being C2 to C14 diamines or alkane diols or any mixture thereof.

[0160] In a certain embodiment, the chain extender is at least one C2 to C14 polyhydric alcohol as described herein above.

[0161] In another certain embodiment, the chain extender is selected from the group consisting of 1 ,2-ethylene glycol, 1 ,2-propanediol, 1,3-propanediol, 1 ,4-butanediol, 2,3-butanediol, 1 ,5-pentanediol, 1,6-hexanediol, diethylene glycol, di-, tri-, tetra-, penta-, hexa-, hepta-, okta-, nona- and / or deca alkylene glycole dipropylene glycol, 1,4-cyclohexanediol, 1 ,4-dimethanol cyclohexane, neopentylglycol and hydroquinone bis (beta-hydroxyethyl) ether (HQEE) and any mixture thereof. In a specific embodiment, the chain extender selected from the group consisting of 1 ,2-ethylene glycol, 1,3-propanediol, 1 ,4-butanediol, and 1,6-hexanediol, di-, tri, tetra-, penta-, hexa-, hepta-, okta-, nona- and / or deca alkylene glycole, preferably respective oligo- and / or polyalkylene glycole and any mixture thereof. In another specific embodiment the chain extender comprises 1 ,2-ethylenediol, 1,3-propanediol, 1 ,4-butanediol or 1,6-hexanediol, or a mixture thereof. Preferably, the chain extender comprises 1,4-butane diol.

[0162] In order to prepare the thermoplastic polyurethane, the building components isocyanate, polyol, and the chain extender, are reacted, in preferred embodiments in the presence of a catalyst, and optionally additives, in such quantities that the equivalent ratio of NCO groups of the isocyanate, preferably the diisocyanate to the sum of the hydroxyl groups of the component reactive with isocyanate is 0.95 : 1 to 1.10 : 1, preferably 0.98 : 1 to 1.08 : 1 and in particular 1.0 : 1 to 1.05 : 1.

[0163] In a specific embodiment, the thermoplastic polyurethane (TPU) is the reaction product of the diisocyanate diphenylmethane-4,4'-diisocyanate, a chain extender essentially consisting of 1 , 4-butand iole and a polyesterpolyol being the reaction product of adipic acid and 1 ,4-butandiole.In another specific embodiment, the thermoplastic polyurethane (TPU) is the reaction product of the diisocyanate diphenylmethane-4,4'-diisocyanate, a chain extender essentially consisting of 1 ,4-butandiole and a polyetherpolyol being the reaction product of adipic acid and Pluronic® F-127.

[0164] In one more embodiment, the thermoplastic polyurethane (TPU) is selected from the Elastollan ® Type thermoplastic polyurethanes.

[0165] The thermoplastic polyurethane (TPU) may comprise one or more additives. The polyols, isocyanates and chain extenders, may also have added to them customary auxiliaries. Examples are surface-active substances, flame retardants, nucleating agents, lubricating and demolding aids, dyes and pigments, stabilizers, for example against hydrolysis, light, heat or discoloration, inorganic and / or organic fillers, reinforcing agents, plasticizers and metal deactivators. Hydrolysis control agents used are preferably oligomeric and / or polymeric aliphatic or aromatic carbodiimides. To stabilize the polyurethane of the present invention against aging, the polyurethane preferably has stabilizers added to it. Stabilizers for the purposes of the present invention are additives which protect a plastic or a plastic mixture against harmful environmental effects. Examples are primary and secondary antioxidants, thiosynergists, organophosphorus compounds of trivalent phosphorus, hindered amine light stabilizers, UV absorbers, hydrolysis control agents, quenchers and flame retardants. Examples of commercial stabilizers are given in Plastics Additive Handbook, 5th Edition, H. Zweifel, ed., Hanser Publishers, Munich, 2001, p. 98 - p.136. When the polyurethane of the present invention is exposed to thermal oxidative damage, during use, antioxidants can be added. Preference is given to using phenolic antioxidants. Examples of phenolic antioxidants are given in Plastics Additive Handbook, 5th edition, H. Zweifel, ed, Hanser Publishers, Munich, 2001, pp. 98 - 107 and p.116 - p.121. Preference is given to phenolic antioxidants having a molecular weight greater than 700 g / mol. One example of a phenolic antioxidant which is preferably used is pentaerythrityl tetrakis (3-(3,5-bis(1 ,1 -dimethylethyl)-4-hydroxyphenyl)propionate) (Irganox® 1010) or other high molecular weight condensation products formed from corresponding antioxidants. The phenolic antioxidants are generally used in concentrations of between 0.1% and 5% by weight, preferably between 0.1% and 2% by weight and especially between 0.5% and 1.5% by weight, all based on the total weight of the polyurethane. Preference is further given to using antioxidants which are amorphous or liquid. Even though the polyurethanes of the present inventio n are by virtue of their preferable composition distinctly more stable to ultraviolet radiation than, for example, polyurethanes plasticized with phthalates or benzoates, stabilization with phenolic stabilizers only is often insufficient. For this reason, the polyurethanes of the present invention which are exposed to UV light are preferably additionally stabilized with a UV absorber. UV absorbers are molecules which absorb high energy UV light and dissipate the energy. UV absorbers widely used in industry belong for example to the group of the cinnamic esters, the diphenyl cyanoacrylates, the oxamides (oxanilides), more particularly 2-ethoxy-2'-ethyloxanilide, the formamidines, the benzylidenemalonates, the diarylbutadienes, triazines and also the benzotriazoles. Examples of commercial UV absorbers are given in Plastics Additive Handbook, 5th edition, H.Zweifel, ed, Hanser Publishers, Munich, 2001 pp.116-122. In a preferred embodiment, the UV absorbers have a number average molecular weight greater than 300 g / mol and more particularly greater than 390 g / mol.

[0166] Furthermore, the UV absorbers which are preferably used should have a molecular weight of not greater than 5000 g / mol and more preferably of not greater than 2000 g / mol. The group of the benzotriazoles is particularly useful as UV absorbers. Examples of particularly useful benzotriazoles are Tinuvin® 213, Tinuvin® 328, Tinuvin® 571, and also Tinuvin® 384 and Eversorb®82. The UV absorbers are preferably added in amounts between 0.01% and 5% by weight, based on the total mass of polyurethane, more preferably between 0.1% and 2.0% by weight and especially between 0.2% and 0.5% by weight, all based on the total weight of the polyurethane. Often, an above-described UV stabilization based on an antioxidant and a UV absorber is still not sufficient to ensure good stability for the polyurethane of the present invention against the harmful influence of UV rays. In this case, a hindered amine light stabilizer (HALS) can preferably be added in addition to the antioxidant and the UV absorber. A particularly preferred UV stabilization comprises a mixture of a phenolic stabilizer, a benzotriazole and a HALS compound in the above-described preferred amounts. However, it is also possible to use compounds which combine the functional groups of the stabilizers, for example sterically hindered piperidylhydroxybenzyl condensation products such as for example di(1 ,2,2,6,6-pentamethyl-4-piperidyl) 2-butyl-2-(3,5-di-tert-butyl-4-hydroxybenzyl) malonate, Tinuvin® 144.

[0167] In one embodiment, the membrane (M) comprises up to 30% by weight of the thermoplastic polyurethane (TPU) based on the total weight of the membrane matrix polymer (M).

[0168] In another embodiment, the membrane (M) comprises up to 29% by weight of the thermoplastic polyurethane (TPU) based on the total weight of the membrane matrix polymer (M). In yet another embodiment, the membrane (M) comprises up to 28% by weight of the thermoplastic polyurethane (TPU) based on the total weight of the membrane matrix polymer (M). In yet another embodiment, the membrane (M) comprises up to 26% by weight of the thermoplastic polyurethane (TPU) based on the total weight of the membrane matrix polymer (M). In yet another embodiment, the membrane (M) comprises up to 25% by weight of the thermoplastic polyurethane (TPU) based on the total weight of the membrane matrix polymer (M). In yet another embodiment, the membrane (M) comprises up to 24% by weight of the thermoplastic polyurethane (TPU) based on the total weight of the membrane matrix polymer (M). In yet another embodiment, the membrane (M) comprises up to 23% by weight of the thermoplastic polyurethane (TPU) based on the total weight of the membrane matrix polymer (M). In yet another embodiment, the membrane (M) comprises up to 21 % by weight of the thermoplastic polyurethane (TPU) based on the total weight of the membrane matrix polymer (M). In yet another embodiment, the membrane (M) comprises up to 19% by weight of the thermoplastic polyurethane (TPU) based on the total weight of the membrane matrix polymer (M). In yet another embodiment, the membrane (M) comprises up to 18% by weight of the thermoplastic polyurethane (TPU) based on the total weight of the membrane matrix polymer (M). In yet another embodiment, the membrane (M) comprises up to 17% by weight of the thermoplastic polyurethane (TPU) based on the total weight of the membrane matrix polymer (M). In yet another embodiment, the membrane (M)comprises up to 15% by weight of the thermoplastic polyurethane (TPU) based on the total weight of the membrane matrix polymer (M). In yet another embodiment, the membrane (M) comprises up to 13% by weight of the thermoplastic polyurethane (TPU) based on the total weight of the membrane matrix polymer (M). In yet another embodiment, the membrane (M) comprises up to 11 % by weight of the thermoplastic polyurethane (TPU) based on the total weight of the membrane matrix polymer (M). In yet another embodiment, the membrane (M) comprises up to 9% by weight of the thermoplastic polyurethane (TPU) based on the total weight of the membrane matrix polymer (M). In yet another embodiment, the membrane (M) comprises up to 6% by weight of the thermoplastic polyurethane (TPU) based on the total weight of the membrane matrix polymer (M). In yet another embodiment, the membrane (M) comprises up to 5% by weight of the thermoplastic polyurethane (TPU) based on the total weight of the membrane matrix polymer (M).

[0169] In a further embodiment, the membrane (M) comprises from 1 to 15% by weight of the thermoplastic polyurethane (TPU) based on the total weight of the membrane matrix polymer (M). In yet a further embodiment, the membrane (M) comprises from 1 to 11 % by weight of the thermoplastic polyurethane (TPU) based on the total weight of the membrane matrix polymer (M). In a further embodiment, the membrane (M) comprises from 1 to 8% by weight of the thermoplastic polyurethane (TPU) based on the total weight of the membrane matrix polymer (M). In a further embodiment, the membrane (M) comprises from 1 to 7% by weight of the thermoplastic polyurethane (TPU) based on the total weight of the membrane matrix polymer (M). In a further embodiment, the membrane (M) comprises from 1 to 6% by weight of the thermoplastic polyurethane (TPU) based on the total weight of the membrane matrix polymer (M). In a further embodiment, the membrane (M) comprises from 1 to 5% by weight of the thermoplastic polyurethane (TPU) based on the total weight of the membrane matrix polymer (M). In a further embodiment, the membrane (M) comprises from 1 to 4% by weight of the thermoplastic polyurethane (TPU) based on the total weight of the membrane matrix polymer (M).

[0170] In a further embodiment, the membrane (M) comprises at least 0.1% by weight of the thermoplastic polyurethane (TPU) based on the total weight of the membrane matrix polymer (M). In yet a further embodiment, the membrane (M) comprises at least 0.2% by weight of the thermoplastic polyurethane (TPU) based on the total weight of the membrane matrix polymer (M). In a further embodiment, the membrane (M) comprises at least 0.3% by weight of the thermoplastic polyurethane (TPU) based on the total weight of the membrane matrix polymer (M). In a further embodiment, the membrane (M) comprises at least 0.5% by weight of the thermoplastic polyurethane (TPU) based on the total weight of the membrane matrix polymer (M). In a further embodiment, the membrane (M) comprises at least 0.7% by weight of the thermoplastic polyurethane (TPU) based on the total weight of the membrane matrix polymer (M). In a further embodiment, the membrane (M) comprises at least 0.9% by weightof the thermoplastic polyurethane (TPU) based on the total weight of the membrane matrix polymer (M). In a further embodiment, the membrane (M) comprises at least 1.0% by weight of the thermoplastic polyurethane (TPU) based on the total weight of the membrane matrix polymer (M). In a further embodiment, the membrane241410

[0171] 26

[0172] (M) comprises at least 2.0% by weight of the thermoplastic polyurethane (TPU) based on the total weight of the membrane matrix polymer (M).

[0173] In one embodiment the molecular weight Mw of the thermoplastic polyurethane (TPU) is in the range of 25.000-500.000 g / mol. In another embodiment the molecular weight Mw of the thermoplastic polyurethane (TPU) is in the range of 50.000-300.000 g / mol. In a preferred embodiment, the molecular weight Mw of the thermoplastic polyurethane (TPU) is in the range of 60.000-200.000 g / mol.

[0174] According to any embodiment, the membrane (M) has a pure water permeability of from 5 - 1.200 kg / h m2bar.

[0175] In one embodiment, the technical membrane (M) has a pure water permeability of from 100 - 1.200 kg / h m2bar. In another embodiment, the membrane (M) has a pure water permeability of from 100 - 1000 kg / h m2bar. In yet another embodiment, the membrane (M) has a pure water permeability of from 100 - 1000 kg / h m2bar. In yet another embodiment, the membrane (M) has a pure water permeability of from 100 - 800 kg / h m2bar.

[0176] In a certain embodiment, the membrane (M) has a pure water permeability of more than 200 kg / h m2bar. In another certain embodiment, the membrane (M) has a pure water permeability of more than 300 kg / h m2bar. In another certain embodiment, the membrane (M) has a pure water permeability of more than 400 kg / h m2bar. In another certain embodiment, the membrane (M) has a pure water permeability of more than 500 kg / h m2bar. In another certain embodiment, the membrane (M) has a pure water permeability of more than 600 kg / h m2bar. In another certain embodiment, the membrane (M) has a pure water permeability of more than 700 kg / h m2bar.

[0177] In one embodiment, the dialyser membrane (M) has a pure water permeability of from 5 - 400 kg / h m2bar.

[0178] In another embodiment, the dialyser membrane (M) has a pure water permeability of from 5 - 300 kg / h m2bar. In yet another embodiment, the dialyser membrane (M) has a pure water permeability of from 10 - 200 kg / h m2bar. In yet another embodiment, the dialyser membrane (M) has a pure water permeability of from 10 - 150 kg / h m2bar. In yet another embodiment, the dialyser membrane (M) has a pure water permeability of from 10 - 100 kg / h m2bar.

[0179] In a certain embodiment, the dialyser dialyser membrane (M) has a pure water permeability of more than 20 kg / h m2bar. In another certain embodiment, the dialyser membrane (M) has a pure water permeability of more than 30 kg / h m2bar. In another certain embodiment, the dialyser membrane (M) has a pure water permeability of more than 40 kg / h m2bar. In another certain embodiment, the dialyser membrane (M) has a pure water permeability of more than 50 kg / h m2bar. In another certain embodiment, the dialyser membrane (M) has a pure water permeability of more than 60 kg / h m2bar. In another certain embodiment, the dialyser membrane (M) has a pure water permeability of more than 70 kg / h m2bar. In another certain embodiment, the dialyser membrane (M)241410

[0180] 27

[0181] has a pure water permeability of more than 80 kg / h m2bar. In another certain embodiment, the dialyser membrane (M) has a pure water permeability of more than 90 kg / h m2bar. In another certain embodiment, the dialyser membrane (M) has a pure water permeability of more than 100 kg / h m2bar.

[0182] In one embodiment, the membrane (M) comprises at least one water-soluble polymer additive (A). In another embodiment, the at least one additive (A) is selected from the group consisting of poly(vinyl pyrrolidone), poly(alkylene oxide), sulfonated poly(arylene ether sulfone) polymer (SP) and mixtures thereof. In a further embodiment, the at least one water-soluble polymer is selected from the group consisting of poly(vinyl pyrrolidone), polyethylene oxide), polypropylene oxide), polyethylene oxide) / poly(propylene oxide) -block-copolymer , sulfonated poly(arylene ether sulfone) polymer (SP) and any mixtures thereof.

[0183] Poly(vinyl pyrrolidone) is commercially available, e.g. Luvitec® from BASF SE. According to one embodiment, the PVP has a solution viscosity characterized by a K-value of at least 12 (PVP K12), of at least 30 (PVP K30) or of at least 85 (PVP K85). It may be preferred, if the PVP has a solution viscosity characterized by a K-value of at least 80 (PVP K80), such as for example Luvitec® K80. In a further preferred embodiment, the PVP has a solution viscosity characterized by a K-value of at least 85 (PVP K85), such as for example Luvitec® K85. It may be also preferred, if the PVP has a solution viscosity characterized by a K-value of at least 90 (PVP K90), such as for example Luvitec® K90.

[0184] The solution viscosity is determined according to the method of Fikentscher (Fikentscher, Cellulosechemie 13, 1932 (58).

[0185] In a certain embodiment, the additive (A) comprises poly (vinyl pyrrolidone) (PVP).

[0186] More preferably, the hydrophilic polymer additive (A) comprises at least 50% by weight, preferably at least 60% by weight, in particular at least 70% by weight of PVP in relation to the amount of additive (A) in the membrane. In a preferred embodiment, the hydrophilic polymer additive (A) consists of poly (vinyl pyrrolidone) as defined and preferably herein. In one embodiment, the membrane (M) comprises PVP as defined and preferably defined herein.

[0187] If present, the amount of PVP, as defined and preferably defined herein, in the inventive membrane (M) is preferably from 0.1 to 5% by weight based on the total weight of the membrane, more specifically from 0.2 to 3% by weight, even more specifically from 0.3 to 2% by weight. In a further embodiment, the amount of PVP in the inventive membrane is from 0.4 to 1.5% by weight, more specifically from 0.5 to 1.3% by weight, even more specifically from 0.6 to 1.2% by weight. In still a further embodiment, the amount of PVP is from 0.7 to 1.1% by weight. In particular PVP may be present in an amount of 0.1 to 1% by weight, more specifically 0.3 to 1% by weight.241410

[0188] 28

[0189] In still a further embodiment, the additive (A) preferably comprises a sulfonated poly(arylene ether sulfone) polymer (SP). Preferably, the hydrophilic polymer additive (A) comprises at least 50% by weight, preferably at least 60% by weight, in particular at least 70% by weight of a sulfonated poly(arylene ether sulfone) polymer (SP) in relation to the amount of additive (A) in the membrane. In a preferred embodiment, the hydrophilic polymer additive (A) consists of at least one sulfonated poly(arylene ether sulfone) polymer (SP) as defined and preferably herein. In one embodiment, the membrane (M) comprises at least one sulfonated poly(arylene ether sulfone) polymer (SP) as defined and preferably defined herein.

[0190] If present, the amount of sulfonated poly(arylene ether sulfone) polymer (SP) in the inventive membrane (M) is preferably from 0.1 to 5% by weight based on the total weight of the membrane, more specifically from 0.2 to 3% by weight, even more specifically from 0.3 to 2% by weight. In a further embodiment, the amount of sulfonated poly(arylene ether sulfone) polymer (SP) in the inventive membrane is from 0.4 to 1.5% by weight, more specifically from 0.5 to 1.3% by weight, even more specifically from 0.6 to 1.2% by weight. In still a further embodiment, the amount of sulfonated poly(arylene ether sulfone) polymer (SP) is from 0.7 to 1.1% by weight. In particular, sulfonated poly(arylene ether sulfone) polymer (SP) may be present in an amount of 0.1 to 1% by weight, more specifically 0.3 to 1% by weight.

[0191] In one certain embodiment of the present invention, the inventive membrane (M) is essentially free from sulfonated poly(arylene ether sulfone) polymer (SP). “Essentially free” within the context of the present invention means that the membrane comprises at most 0.05% by weight, preferably at most 0.04% by weight and particularly preferably at most 0.03% by weight, more specifically at most 0.01 % by weight of sulfonated poly(arylene ether sulfone) polymer (SP) based on the total weight of the membrane. According to one very specific embodiment, the inventive membrane (M) does not contain any sulfonated poly(arylene ether sulfone) polymer (SP).

[0192] In a further embodiment of the invention, the membrane (M) comprises poly (vinyl pyrrolidone) (PVP) as defined and preferably defined above and a sulfonated poly(arylene ether sulfone) polymer (SP) as defined and preferably defined above.

[0193] In a further embodiment, the at least one additive (A) comprises poly(alkylene oxides), in particular selected from poly (ethylene oxide), polypropylene oxide) and poly (ethylene oxide)-poly(propylene oxide) copolymers.

[0194] In a further embodiment of the invention, the membrane (M) comprises poly(alkylene oxides) selected from poly (ethylene oxide), polypropylene oxide) and polypthylene oxide)-poly(propylene oxide) copolymers.

[0195] If present, the amount of poly(alkylene oxides) in the inventive membrane (M) is preferably from 0.1 to 5% by weight based on the total weight of the membrane, more specifically from 0.2 to 3% by weight, even more specifically from 0.3 to 2% by weight. In a further embodiment, the amount of poly(alkylene oxides) in the241410

[0196] 29

[0197] inventive membrane is from 0.4 to 1.5% by weight, more specifically from 0.5 to 1.3% by weight, even more specifically from 0.6 to 1.2% by weight. In still a further embodiment, the amount of poly(alkylene oxides) is from 0.7 to 1.1% by weight. In particular, poly(alkylene oxides) may be present in an amount of 0.1 to 1 % by weight, more specifically 0.3 to 1 % by weight.

[0198] As is self-explanatory for the skilled person, all constituents of the membrane (M) add up to 100% by weight.

[0199] In a certain embodiment, the water-soluble polymer has a number average molar mass Mnof at least 250 g / mol. In another certain embodiment, the water-soluble polymer has a number average molar mass Mnof at least 276 g / mol. In another certain embodiment, the water-soluble polymer has a number average molar mass Mnof at least 304 g / mol. In another certain embodiment, the water-soluble polymer has a number average molar mass Mnof at least 349 g / mol. In another certain embodiment, the water-soluble polymer has a number average molar mass Mnof at least 401 g / mol. In another certain embodiment, the water-soluble polymer has a number average molar mass Mnof at least 461 g / mol. In another certain embodiment, the water-soluble polymer has a number average molar mass Mnof at least 508 g / mol.

[0200] In a specific embodiment, the membrane (M) does not contain any water-soluble polymer additive (A). In another specific embodiment of the present invention, the inventive membrane (M) is essentially free from PVP.

[0201] “Essentially free” within the context of the present invention means that the membrane comprises at most 0.05 % by weight, preferably at most 0.04 % by weight and particularly preferably at most 0.03 % by weight, more specifically at most 0.01 % by weight of PVP based on the total weight of the membrane. According to one very specific embodiment, the inventive membrane (M) does not contain any PVP.

[0202] In a second aspect, the present invention relates to a process for producing a membrane (M) as described herein comprising the steps of:

[0203] a) preparing a dope solution comprising at least one of poly(arylene ether sulfone) polymers (P1 ) and (P2), and a thermoplastic polyurethane (TPU) according to the present invention, and a water-soluble polymer in a polar aprotic solvent;

[0204] b1) optionally, shaping the polymer solution into a desired certain geometry;

[0205] b2) solidifying the polymer solution obtained from step a) or optionally the geometry shaped in step b1) by exposing the polymer solution to a coagulant; and

[0206] b3) optionally, removal of water-soluble polymer and solvent.241410

[0207] 30

[0208] In one embodiment, the polar aprotic solvent as used in step a) is selected from the group consisting of high-boiling ethers, esters, ketones, asymmetrically halogenated hydrocarbons, anisole, y-valerolactone, N,N-dimethylformamide, dimethylsulfoxide, dihydrolevoglucosenone, methyl-5-(dimethylamino)-2-methyl-5-oxopentanoate, sulfolane, N-methyl-2-pyrrolidone, N-ethyl-2 pyrrolidone, N, N-butyl-2-pyrrolidone, N-tert-butyl-2-pyrrolidone, N,N dimethyl-2-hydroxypropanoic amide, N, N-diethyl-2 hydroxypropanoic amide, methyl-1 -methyl-2-oxopyrrodlidone -4-carboxylate, N-(2’-hydroxyethyl)-2-pyrrolidone and 2-(2-oxopyrrolidin-1 -yl)ethyl acetate and any mixture thereof.

[0209] In one embodiment, the poly(arylene ether sulfone) polymers (P1) and (P2) are combined with the thermoplastic polyurethane (TPU) in a ratio from 85 (P1 and P2) : 15 (TPU) (wt% / wt%) to 99,9 : 0,1 (wt% / wt%), based on the total weight of the combined polymers.

[0210] In one embodiment the dope solution comprises 10-25% by weight of a polymer mixture comprising the poly(arylene ether sulfone) polymers (P1) and (P2), and the thermoplastic polyurethane (TPU) according to the present invention, preferably 15-20% by weight, 1-10% by weight of at least one water soluble polymer, preferably 5-8% by weight, 1-15% by weight of at least one non-solvent additive, preferably 3-10% by weight, 50-88% by weight of at least one solvent; all based on the total weight of the polymer dope solution. In another embodiment, the poly(arylene ether sulfone) polymers (P1) and (P2) are the same or different.

[0211] In one embodiment, the poly(arylene ether sulfone) polymers (P1) and (P2) are combined with the thermoplastic polyurethane (TPU) in a ratio from 70 : 30 (wt.% / wt.%) to 99,9 : 0,1 (wt.% / wt.%), based on the total weight of the combined polymers. It is to be understood that the term “wt.%” is synonymously used with the term “% by weight”

[0212] In another embodiment, the poly(arylene ether sulfone) polymers (P1) and (P2) are combined with the thermoplastic polyurethane (TPU) in a ratio from 80 : 20 (wt.% / wt.%) to 99,9 : 0,1 (wt.% / wt.%), based on the total weight of the combined polymers.

[0213] In yet another embodiment, the poly(arylene ether sulfone) polymers (P1) and (P2) are combined with the thermoplastic polyurethane (TPU) in a ratio from 85 : 15 (wt.% / wt.%) to 99,9 : 0,1 (wt.% / wt.%), based on the total weight of the combined polymers.

[0214] In yet another embodiment, the poly(arylene ether sulfone) polymers (P1) and (P2) are combined with the thermoplastic polyurethane (TPU) in a ratio from 90 : 10 (wt.% / wt.%) to 99,9 : 0,1 (wt.% / wt.%), based on the total weight of the combined polymers.

[0215] In a third aspect, the present invention relates to a use of the thermoplastic polyurethane (TPU) according to the present invention for producing a membrane (M).241410

[0216] 31

[0217] In one embodiment, the membrane (M) can be a nanofiltration (NF) membrane, a microfiltration (MF) membrane or an ultrafiltration (UF) membrane. In another embodiment, the membrane (M) is a dialyzer membrane.

[0218] Preferably, the membrane (M) is a membrane according to the present invention.

[0219] In a fourth aspect, the present invention relates to a polymer dope solution comprising 10-25% by weight of a polymer mixture comprising the poly(arylene ether sulfone) polymers (P1) and (P2), and the thermoplastic polyurethane (TPU) according to the present invention, preferably 15-20 % by weight, 1-10% by weight of at least one water soluble polymer, preferably 5-8% by weight, 1-15% by weight of at least one non-solvent additive, preferably 3-10% by weight, 50-88% by weight of at least one solvent; all based on the total weight of the polymer dope solution.

[0220] In one embodiment, the poly(arylene ether sulfone) polymers (P1) and (P2) are the same or different.

[0221] In one embodiment, the polymer dope solution comprising 11-25% by weight of a polymer mixture comprising the poly(arylene ether sulfone) polymers (P1) and (P2). In another embodiment, the polymer dope solution comprising 12-25% by weight of a polymer mixture comprising the poly(arylene ether sulfone) polymers (P1 ) and (P2). In yet another embodiment, the polymer dope solution comprising 13-25% by weight of a polymer mixture comprising the poly(arylene ether sulfone) polymers (P1) and (P2). In yet another embodiment, the polymer dope solution comprising 14-25% by weight of a polymer mixture comprising the poly(arylene ether sulfone) polymers (P1) and (P2). In yet another embodiment, the polymer dope solution comprising 15-25% by weight of a polymer mixture comprising the poly(arylene ether sulfone) polymers (P1) and (P2). In yet another embodiment, the polymer dope solution comprising 16-25% by weight of a polymer mixture comprising the poly(arylene ether sulfone) polymers (P1) and (P2). In yet another embodiment, the polymer dope solution comprising 18-25% by weight of a polymer mixture comprising the poly(arylene ether sulfone) polymers (P1 ) and (P2) .

[0222] In one embodiment, the polymer dope solution comprising 10-23% by weight of a polymer mixture comprising the poly(arylene ether sulfone) polymers (P1) and (P2). In another embodiment, the polymer dope solution comprising 10-22% by weight of a polymer mixture comprising the poly(arylene ether sulfone) polymers (P1 ) and (P2). In yet another embodiment, the polymer dope solution comprising 10-21% by weight of a polymer mixture comprising the poly(arylene ether sulfone) polymers (P1) and (P2). In yet another embodiment, the polymer dope solution comprising 10-19% by weight of a polymer mixture comprising the poly(arylene ether sulfone) polymers (P1) and (P2). In yet another embodiment, the polymer dope solution comprising 10-17% by weight of a polymer mixture comprising the poly(arylene ether sulfone) polymers (P1) and (P2).241410

[0223] 32

[0224] In a certain embodiment, the polymer dope solution comprising 13-20% by weight of a polymer mixture comprising the poly(arylene ether sulfone) polymers (P1) and (P2), and the thermoplastic polyurethane (TPU) according to the present invention, preferably 15-20 % by weight, 1-10% by weight of at least one water soluble polymer, preferably 5-8% by weight, 1-15% by weight of at least one non-solvent additive, preferably 3-10% by weight, 50-88% by weight of at least one solvent; all based on the total weight of the polymer dope solution.

[0225] In a fifth aspect, the present invention relates to the use of the membrane (M) according to the invention or produced by a process according to the invention for dialysis or for ultrafiltration.

[0226] According to any embodiment, the dialyser membrane (M) is used for blood dialysis in mammals, preferably in humans.

[0227] The various embodiments and benefits outlined for the first aspect of the present invention are equally applicable to the second, third fourth and fifth aspects, and conversely, the features and advantages of the first, second, third fourth and fifth aspects can also be understood to apply to each other in any technically reasonable combination.

[0228] Examples

[0229] Abbreviations and compounds used in the examples:

[0230] NMP N-methyl-2-pyrrol idone [872-50-4]

[0231] DMF N,N-Dimethylformamide [68-12-2]

[0232] DMAc N,N-Dimethyactamide [127-19-5]

[0233] GPC gel permeation chromatography

[0234] MWCO molecular weight cut-off

[0235] NTU nephelometric turbidity unit

[0236] PWP pure water permeation

[0237] 1HNMR Proton nuclear magnetic resonance spectroscopy

[0238] Ultrason® E 3010 Poly(ether sulfone) with a viscosity number (ISO 307; in 0.01 g / mol phenol / 1,2

[0239] orthodichlorobenzene 1 : 1 solution) of 66; a glass transition temperature (DSC, 10°C / min; according to ISO 11357-1 / -2) of 225 °C; a molecular weight Mw (GPC in THF, PS standard): 58000 g / mol, Mw / Mn = 3.3 which is abbreviated “E3010” Ultrason® E 6020 P Poly(ether sulfone) with a viscosity number (measured based on ISO 1628-5 (1998) in a 1 wt.-% polymer solution in N-methylpyrrolidone) of 81 ml / g; a glass transition temperature (DSC, 10 K / min; according to ISO 11357-11-2 from 2014) of 225 °C; a241410

[0240] 33

[0241] molecular weight Mw(GPC in THF, PS standard) of 75000 g / mol, and Mw / Mn= 3, which is abbreviated as “E6020P”.

[0242] Luvitec® K90 Poly(vinyl pyrrolidone) with a molecular weight (GPC in DMAc, PS standard): Mwof 1000000 to 1500000 g / mol and a solution viscosity characterized by the K-value of 90, determined according to the method of Finkentscher (Finkentscher, Cellulosechemie 13, 1932 (58)), which is abbreviated as “K90”.

[0243] Luvitec® K85 Poly(vinyl pyrrolidone) with a molecular weight Mwof 1100000 g / mol and a solution viscosity characterized by the K-value of 85, determined according to the method of Fikentscher (Fikentscher, Cellulosechemie 13, 1932 (58)), which is abbreviated as “K85”.

[0244] Luvitec® K30 Poly (vinyl pyrrolidone) with a molecular weight Mwof 44000 to 540000 g / mol and a solution viscosity characterized by the K-value of 30, determined according to the method of Fikentscher (Fikentscher, Cellulosechemie 13, 1932 (58)), which is abbreviated as “K30”.

[0245] Synthesis of TPU variant 1 and 2

[0246] Table 1 : Recipe for compositions of TPU variant 1 and 2.

[0247]

[0248] *Polyol 1 : 2.0 functiona , 111,4 mgKOH / g OH number based on adipic acid and 1 ,4-butane diol

[0249] The extruder was charged with butane-1 ,4-diol, polyol 1 and, separately therefrom, the diphenylmethane 4,4'-diisocyanate according to table 1 was metered into the first housing. The speed of the twin screw was 225 min-1. The set temperature values for the housing were, in flow direction, 210° C and in the first charging zone of the screw, 180° C. After the melt chopping by underwater pelletization and integrated centrifugal drying, the pellets were subjected to final drying at about 80 to 90° C.

[0250] Determination of solution viscosity241410

[0251] 34

[0252] The polymer solution viscosity was measured with a Brookfield Viscometer DV-I Prime (Brookfield Engineering Laboratories, Inc. Middleboro, USA) with RV 6 spindle at 60 °C with 5-100 rpm. The utilized shear rate is dependent on the solution viscosity and is given in the tables below.

[0253] Determination of the membrane pure water permeability

[0254] The pure water permeability (PWP) of the membranes was tested using a pressure cell with a diameter of 74 mm using ultrapure water (salt-free water, filtered by a Millipore UF-system) at 23 °C and 1 bar water pressure. The pure water permeability (PWP) is calculated as follows (equation 1):

[0255] m

[0256] PWP =

[0257] AxPxt

[0258]

[0259] PWP: pure water permeability [kg / bar h m2]

[0260] m: mass of permeated water [kg]

[0261] A: membrane area [m2]

[0262] P: pressure [bar]

[0263] t: time of the permeation experiment [h].

[0264] Determination of the membrane’s MWCO

[0265] In a subsequent test, solutions of polyethylene oxide) -standards with increasing molecular weight were used as feed to be filtered by the membrane at a pressure of 0.15 bar. By GPC-measurement of the feed and permeate, the molecular weight of the permeate of each poly(ethy lene oxide)-standard used was determined.

[0266] Film thickness

[0267] The film thickness is measured with a Mitutoyo ID-C112XB (Mitutoyo Corporation, Kawasaki, Japan).

[0268] BET surface assessment

[0269] Solvent exchanged and dried membrane samples are used for Brunauer-Emmet-Teller (BET) surface assessment. The wet membrane samples are stored for 12 h subsequently in water / ethanol (1:1 wt. / wt.), water / ethanol (1 :2 wt. / wt.), ethanol / n-hexane (1:1 wt. / wt.) and finally n-hexane before drying at 60 °C under vacuum.

[0270] The BET surface is determined by gas-adsorption-desorption (GAD) experiments with nitrogen by 5-point method with ASAP 2420 (Fa. Micromeritics, Norcross, USA). The samples are activated at 130 °C for 15 min before measurement.

[0271] Determination of the membrane’s mechanical stability241410

[0272] 35

[0273] Tensile testing was carried out according DIN Iso 527-3 and the wet membranes characterized regarding E-modulus (Emod MPa), strain at break (ebreak %) and strain at maximum force (epmax %) in order to assess the mechanical stability.

[0274] Preparation of monolithic films - General procedure

[0275] 20 g polymer and 80 g of DMAc as given in table 2 were mixed using a SpeedMixer® DAC 600.1 Vac-P (Hauschild & Co. KG, Hamm, Germany) at speeds of 200, 800 and 1200 rpm within 30 minutes of mixing. The solution was degassed overnight at room temperature. After that the membrane solution was reheated at 60°C for 2 hours and casted onto a glass plate with a casting knife (300 microns) at 60°C using an Erichsen Coating machine operating at a speed of 5 mm / s. The solvent was evaporated at 50 °C at 10 mbar overnight and the dried film transferred on the glass plate into a water bath at 25 °C for 10 minutes. After the film had detached from the glass plate it was subjected extraction with water at 80 °C (160 liters / 20 hours) overnight.

[0276] Table 2: Compositions and properties of E 3020 P and E 3020 P / TPU blend solutions films prepared thereof; Visco@60°C [mPas], turbidity@60°C [NTU], thickness [pm], elongation at maximum force epmax and tear break

[0277]

[0278] Preparation of technical membranes - General procedure

[0279] The amounts given in this general procedure are general ranges, the exact amount for the respective experiment can be found in table 3. The polymer dope solution for membrane preparation was prepared using a SpeedMixer® DAC 600.1 Vac-P (Hauschild & Co. KG, Hamm, Germany) at speeds of 200, 800 and 1200 rpm within 30 minutes of mixing. The solution was degassed overnight at room temperature.

[0280] After that, the membrane solution was reheated at 60 °C for 2 hours and casted onto a glass plate with a casting knife (300 microns) at 60 °C using an Erichsen Coating machine (Coatmaster 510, Erichsen GmbH & Co KG, Hemer, Germany) operating at a speed of 5 mm / s. The membrane film was allowed to rest for 30 seconds before immersion at 25 °C for 10 minutes in a water-based coagulation bath consisting of a mixture of water and glycerol at a ratio of 60:40 based on weight. After the membrane had detached from the glass plate, the membrane was exposed to a water bath containing a 2000 ppm NaOCI solution at 60 °C and a pH of 9.5 for 2 h. The membrane was then washed with water at 60 °C and one time with a 0.5 wt.-% solution of sodium bisulfite to remove active chlorine. After the posttreatment the membranes are stored in a wet state.241410

[0281] 36

[0282] Table 3: Compositions of TPU variant 1 and Ultrason® E 3010 solutions prepared with PVP in NMP.

[0283]

[0284] Table 4: Properties of TPU variant 1 and Ultrason® E 3010 membranes prepared from membrane solutions according to table 2; coagulation water-glycerol (60 / 40 wt / wt) and post treatment in NaOCI (2000 ppm, pH9.5, 60 °C, 2 h), PWP [kg / h m2bar] , MWCO [kDa], BET surface [m2 / g], Emodulus [MPa], elongation at maximum force eFmax and tear break ebreak [%]

[0285]

[0286] state of the art comparable ultrafiltration performance (MWC0< 50 kDa; PWP > 700 kg / h m2bar) and strength as shown from the identical Emoduli, but better flexibility as shown from the 50% higher values of elongation at maximum force and tear break. As can be seen in Figures 1 and 2, PESU-TPU blends are forming under comparable non-solvent induced phase separation conditions identical fine porous ultrafiltration membranes without maco-voids compared to membranes based only on PESU.

[0287] Table 5: Recipe for compositions of TPU3 and TPU4.

[0288]

[0289] *Polyol 1 : 2.0 functiona , 75 mgKOH / g OH number based polyethylene glycole

[0290] The OH number was measured according to DIN 53240-2: 2007-11. Samples were prepared according to the following procedure:

[0291] The extruder was charged with, polyol 1, butane-1 ,4-diol and 1 ,3-propandiole and, separately therefrom, the diphenylmethane 4, 4'-d iisocy anate was metered into the first housing according to table 1. The speed of the twin screw was 200 min-1. The set temperature values for the housing were, in flow direction, 215° C. After the melt241410

[0292] 37

[0293] chopping by underwater pelletization and integrated centrifugal drying, the pellets were subjected to final drying at about 80 to 90° C.

[0294] Determination of solution turbidity

[0295] The polymer solution turbidity is measured with a turbidimeter 2100AN (Hach Lange GmbH, Dusseldorf, Germany) employing a filter of 860 nm at 60 °C and expressed in nephelometric turbidity units (NTU).

[0296] Determination of polymer blend water contact angle (CA)

[0297] The contact angle (CA) of the polymer films is measured at 23 °C by placing 8 to 10 drops of deionized water with a volume of approximately 2 pL on the sample. The contact angle is determined by time-resolved automated image analysis by Kruss DSA100 (A. KRUSS Optronic GmbH, Hamburg, Germany).

[0298] Determination of the membrane's static protein adsorption

[0299] Protein adsorption testing for albumin and myoglobin was performed according to literature [A. Schulze, B. Marquardt, M. Went, A. Prager and M. R. Buchmeiser, Electron beam-based functionalization of polymer membranes, Water Science & Technology 2012, 65.3, 574. DOI: 10.2166 / wst.2O12.]. Myoglobin from equine heart (Product No. M1882-1G)from Sigma Aldrich Germany, lyophilized albumin bovine serum (Product No. A2153-10G) from Sigma Aldrich Germany, (phosphate buffer solution (1 M, pH 7.4 at 25 °C, Solution B) ordered from Sigma Aldrich, Germany (Product No. P3619-1GA). Membrane samples of 1 cm diameter were exposed to the proteins in phosphate buffer solutions at pH 7.4 (Solution A: 2 mg ml1albumin or myoglobin) and subsequently the quantity of proteins adsorbed on the membrane surface determined with bicinchoninic acid assay (BCA) und UV detection at 562 nm. The BCA testing assay was obtained from Merck KGaA, Darmstadt, Germany (Product No. 71285-3, 500 assays).

[0300] Preparation of monolithic films were done according to the General procedure as described above.

[0301] Table 6: Compositions and properties of E 3010 and E 3010 / TPU blend solutions, viscosity at room temperature [mPas], turbidity at room temperature [NTU],

[0302]

[0303] 241410

[0304] 38

[0305] Table 7: Compositions and properties of E 3010 and E 3010 / TPU blend solutions films prepared thereof; thickness [pm], water contact angle (CA) [°] and glass transition temperature Tg [°C] from DSC (20K / min)

[0306]

[0307] Compared tp pure PESU, the polyarylsulfone thermoplastic polymer polyurethane blends according to the present invention exhibit significantly lower water contact angles indicating a more hydrophilic surface.

[0308] Preparation of hemodialyzer membranes - General procedure

[0309] The amounts given in this general procedure are general ranges, the exact amount for the respective experiment can be found in table 8. The polymer dope solution for membrane preparation was prepared using a SpeedMixer® DAC 600.1 Vac-P (Hauschild & Co. KG, Hamm, Germany) at speeds of 200, 800 and 1200 rpm within 30 minutes of mixing. The solution was degassed overnight at room temperature.

[0310] After that, the membrane solution was reheated at 60 °C for 2 hours and casted onto a glass plate with a casting knife (300 microns) at 60 °C using an Erichsen Coating machine (Coatmaster 510, Erichsen GmbH & Co KG, Hemer, Germany) operating at a speed of 5 mm / s. The membrane film was allowed to rest for 30 seconds before immersion at 25 °C for 10 minutes in a water-based coagulation bath consisting of a mixture of water and NMP at a ratio of 70:30 based on weight. After the membrane had detached from the glass plate, the membrane was exposed to a water bath containing for 6 hours at 60 °C. After the post-treatment the membranes are stored in a wet state.

[0311]

[0312]

[0313] Table 8: Compositions of TPU and Ultrason® E 6020 P solutions prepared with PVP in NMP.

[0314] Table 9: Properties of TPU and Ultrason® E 6020 P membranes prepared from membrane solutions according to table 8; coagulation water-NMP (70 / 30 wt / wt) and post treatment in water (60 °C, 7 h), PWP [kg / h m2bar] and MWCO [kDa]

[0315]

[0316] Table 10: Properties of TPU and Ultrason® E 6020 P membranes prepared from membrane solutions according to table 8; coagulation water-NMP (70 / 30 wt / wt) and post treatment in water (60 °C, 7 h), BET [m2 / g], BCAMY [p

[0317]

[0318]

[0319] Compared to membranes based solely on PESU, the membranes according to the present invention exhibit significantly lower reduced absolute protein adsorption for myoglobin (BCAMY) and albumin (BCAAL) and relative protein adsorption for myoglobin (BACAMY / BET) and albumin (BCAAL / BET), indicating a more hydrophilic and anti-fouling surface. These improvements are achieved without compromising essential membrane performance characteristics such as pure water permeance (PWP) and molecular weight cut-off (MWCO), thereby enabling more effective retention of blood constituents like albumin and contributing to enhanced hemocompatibility during dialysis treatment.

Claims

41Claims1. A membrane (M) comprising a polymer matrix consisting of at least one polymer selected from the group consisting of poly(arylene ether sulfone) polymers (P1 ) and (P2), and at least one thermoplastic polyurethane (TPU); wherein (P1) and (P2) each comprises at least one structural repeating unit of the general formula (I)wherein the definitions of the symbols t, q, Q, T, Y, Ar and Ar1are as follows: t, q independently of one another 0, 1 , 2 or 3;Q, T, Y independently of one another a chemical bond or a group selected from -O-, -S-, -SO2-, S=O, C=O, -N=N- and -CRaRb-, wherein Raand Rbindependently of one another are a hydrogen atom, (Ci-Ci2)alkyl, (Ci-Ci2)alkoxy, (C3-Ci2)cycloalkyl or a (Ce-C jaryl group, and wherein at least one of Q, T, and Y is present and is -SO2-; andAr and Ar1independently of one another (Ce-C jarylene; optionally wherein the at least one structural repeating unit of (P2) is different from the at least one structural repeating unit of (P1 ).

2. The membrane according to claim 1 , wherein the polymer matrix is consisting of at least one structural repeating unit for (P1) and (P2), respectively, selected from the unitsor any mixture thereof; optionally wherein the polymer matrix comprises at least 95 wt. -% of the repeating units of formula Ik and la based on the total weight of the polymer matrix.241410423. The membrane according to any one of the preceding claims, wherein the weight average molecular weight Mnof the polymer matrix is in the range from 19.000 to 164.000 g / mol and / or a viscosity number of 60 to 120 ml / g.

4. The membrane according to any one of the preceding claims, wherein the thermoplastic polyurethane (TPU) is the reaction product of at least one isocyanate, at least one isocyanate reactive group, at least one chain extender and optionally comprises one or more additives.

5. The membrane according to claim 4, wherein the isocyanate is selected from the group consisting of aliphatic and aromatic diisocyanates, and any combination thereof.

6. The membrane according to any one of claims 4-5, wherein the isocyanate reactive group is a polyol selected from the group consisting of polyetherpolyols, polycarbonate polyols, polyesterpolyols and any combination thereof.

7. The membrane according to any one of claims 4-6, wherein the chain extender comprises at least one C2 to C14 polyhydric alcohol.

8. The membrane according to any one of the preceding claims, wherein the thermoplastic polyurethane (TPU) comprises at least one polyethylene glycol (PEG) polyol.

9. The membrane according to any one of the preceding claims, wherein the membrane (M) comprises up to 30% by weight of the thermoplastic polyurethane (TPU) based on the total weight of the membrane matrix polymer.

10. The membrane according to any one of the preceding claims wherein the weight average molecular weight cut-off of the membranes (MWCO) of the membrane is at least 5 kDa and optionally up to 100 kDa.

11. The membrane according to any one of the preceding claims, further comprising at least one water soluble polymer additive, preferably selected from the group consisting of poly(vinyl pyrrolidone), poly(alkylene oxide), sulfonated poly(arylene ether sulfone) polymer (SP) and mixtures thereof.

12. A process for producing a membrane according to any one of claims 1 -11 comprising the steps of:a) preparing a dope solution comprising at least one of poly(arylene ether sulfone) polymers (P1) and (P2), and a thermoplastic polyurethane (TPU) according to claim 1, and a water-soluble polymer in a polar aprotic solvent;b1) optionally, shaping the polymer solution into a desired certain geometry;24141043b2) solidifying the polymer solution obtained from step a) or optionally the geometry shaped in step b1) by exposing the polymer solution to a coagulant;b3) optionally, removal of water soluble polymer and solvent.

13. Use of the thermoplastic polyurethane (TPU) according to any one of claims 1 -9 for producing a membrane (M).

14. Use of the membrane (M) according to any one of claims 1-11 or produced by a process according to claim 12 for dialysis or for ultrafiltration.

15. A polymer dope solution obtainable from step a) of the process according to any one of claims 12-14 for producing the membrane according to any one of claims 1-11, comprising:10-25 % by weight of a polymer mixture comprising the poly(arylene ether sulfone) polymers (P1 ) and (P2), and the thermoplastic polyurethane (TPU) according to any one of claims 1 -9,1-10 % by weight of at least one water soluble polymer,1-15 % by weight of at least one non-solvent additive,50-88 % by weight of at least one solvent;all based on the total weight of the polymer dope solution; optionally wherein the poly(arylene ether sulfone) polymers (P1) and (P2) are the same or different.

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