WO1997005190A1

WO1997005190A1 - Block copolymers

Info

Publication number: WO1997005190A1
Application number: PCT/US1996/012421
Authority: WO
Inventors: Lawrence Francis Hancock; Alan Jay Kishbaugh; Marc Ellous Parham
Original assignee: W.R. Grace & Co.
Priority date: 1995-07-27
Filing date: 1996-07-29
Publication date: 1997-02-13
Also published as: AU6682596A

Abstract

An amphiphilic block copolymer including polyethylene oxide or polypropylene oxide and a hydrophobic block segment useful in making polymeric articles, and methods of making such articles.

Description

BLOCK COPOLYMERS

Background of the Invention

Desirable separation membranes are strong, thermally-stable, and resistant to oxidative or corrosive elements in the material to be separated such as acids or chloride ions. Hydrophobic polymers such as polysulfones often provide the above characteristics. When aqueous or polar materials are to be separated, however, a

hydrophilic surface is also desirable. A hydrophilic or wettable surface on a porous polymer promotes uniform filtration, increases recovery of both filtrate and retentate, and decreases adsorption of material such as protein and other solutes (i.e., fouling). It is worth noting that the surface energies associated with small-diameter pores hamper both an initial wetting of a porous surface, and also a re-wetting of the surface after the membrane has been dried.

In addition to one method which simply blends hydrophobic polymers with a hydrophilic additive or alloy, there are several methods of treating pre-formed polymer membranes to increase surface hydrophilicity. For example, one method relies on hydrophobic bonding between a pre-formed hydrophobic polymer and an

adsorptive coating. Much activity has focused on

derivatizing functional groups exposed on the surface of a pre-formed polymer with surface modifying ligands. One method prepares a copolymer with derivatizable functional groups, such as poly[acrylonitrile-co-hydroxyalkyl(meth)acrylate]. Other methods include direct sulfonation, hydroxyalkylation, or other

derivatization of reactive functional groups on a preformed polymer membrane. Summary of the Invention

One aspect of the invention relates to a

hydrophilic-hydrophobic diblock copolymer or a

hydrophilic-hydrophobic-hydrophilic triblock copolymer, or a combination thereof.

An example is a block copolymer having the formula (1):

R-[OCH₂A]_n-X-Y (1) wherein R is H, C_1-20 alkyl, C_7-20 alkylaryl, C_7-20

arylalkyl, or C_1-20 perfluoroalkyl. Each A is

independently selected from CH₂ and CH(CH₃); l n is between 1 and 10,000. X is -Z¹-(OAr¹OAr²)_m- or -(OAr²Q)_m-, Q being OAr¹ or [OCH₂E]_u, wherein m is between 1 and 500, each E is independently selected from CH₂ and CH(CH₃) , and u is between 1 and 10,000. Y is hydroxy, -(OAr³O)-Z²- [BCH₂O]_p-R¹, or -(OAr⁴O)-[BCH₂O]_p-R¹, wherein each B is independently selected from CH₂ and CH(CH₃), and p is between 1 and 10,000. Z¹ is selected from -N(R²)-(SO₂)- C₆H₄- and -N(R²)-(C=O)-C₆H₄-, R² being C_1-12 alkyl or C_6-20 aryl. Z² is selected from -C₆H₄-(SO₂)-N(R³)- and -C₆H₄- (C=O)-N(R³)-, R³ being C_1-12 alkyl or C_6-20 aryl.

R¹ is H, C_1-20 alkyl, C_7-20 alkylaryl, C_7-20 arylalkyl, or ^ci-₂₀ perfluoroalkyl. Each Ar¹ and each Ar³ is

independently selected from 1,4-phenylene, 1,3-phenylene, naphthyl-1, 4-diyl, naphthyl-1, 5-diyl, 4 ,4'-biphenylene, diphenyl ether-4,4'-diyl, diphenylthioether-4,4'-diyl, diphenylisopropyl-idene-4,4'-diyl,

diphenylhexafluoroisopropylidene-4,4'-diyl,

diphenylalkylene-4,4'-diyl wherein alkylene is -(CH₂)_q-, q being 1, 3, 5, 7 or 9, p-terphenyl-4,4'-diyl, and

bivalent radicals of binaphthalene, anthracene, and phenylnaph-thalene; and each Ar² and each Ar⁴ is

independently selected from diphenylsulfoxide-4,4'-diyl, diphenylsulfone-4,4'-diyl, diphenyl ketone-4,4'-diyl, and bivalent radicals of diphenyl-C_{1- 12} alkyl phosphine oxide and diphenyl-C_6-20 aryl phosphine oxide.

Another aspect of the invention features a block copolymer, which includes a central block segment

selected from polyethylene oxide block and a polyethylene oxide-polypropylene oxide copolymer, wherein the segment is linked between two polyarylsulfone block segments by ether linkages; and a first endgroup and a second

endgroup, each endgroup selected independently from polyethylene oxide

C_1-10 alkyl ether and polyethylene glycol mono-C_1-10 alkyl ether and each linked to an arylsulfone moiety connected to one of said polyaryl sulfone block segments.

Another aspect of the invention relates to a porous polymer article with a covalently-bonded

hydrophilic moiety present on its active surface. The polymer article includes (i) a hydrophilic-hydrophobic block copolymer (such as a hydrophilic-hydrophobic diblock copolymer, or a hydrophilic-hydrophobic-hydrophilic triblock copolymer, or a combination thereof, e.g., formula (1) above, or formulae (2) or (3), below), and (ii) a hydrophobic polymer. The polymer matrix of the article is formed by the hydrophobic polymer mixing with hydrophobic block segments of a disclosed block copolymer of formula (1). A hydrophilic moiety includes a partial length or portion of a hydrophilic block segment of the block copolymer.

Still another aspect of the invention features a method of making a porous polymer article with enhanced hydrophilicity including three steps. The first step is providing a casting solution which includes (i) 0.1 - 50 weight percent of a block copolymer of formula (1), (2) or (3), (ii) 0 - 40 weight percent of a hydrophilic polymer, and (iii) 40 - 95 weight percent of a polar aprotic solvent. The second step is contacting the casting solution with a nonsolvent coagulation bath until a porous polymer article forms. The third step thermally annealing the article in the presence of water to enhance the hydrophilicity of the article.

Some important terms used in this disclosure are defined or exemplified below:

The term "active surface" means the total surface area, including pores and channels, exposed to a

filtrate. The invention features block copolymers designed to form polymer articles such as membranes which spontaneously undergo a phase inversion to form an active surface (e.g., a hydrophilic surface). As a result of the design of the block copolymer and the method of formation, the active surface generally extends across the exterior membrane faces and generally extends through the interior pore surfaces and channels. The active surface of an article is therefore generally greater than the macroscopic or planar dimension. Thus, a 4 inch by 4 inch membrane has an active surface greater than 16 square inches.

The term "active surface block segment," or active surface segment, refers to a block segment of a copolymer which is localized at least in part on the active surface of a polymer article during membrane formation (e.g., poly(oxyethylene) block segment in Example 1). Such localization or presentation results from careful

selection of casting solution solvent, block copolymer, additives, temperature, matrix-forming polymer, and coagulation bath medium. An active surface block segment is covalently-bound to an anchor segment of the same block copolymer. An anchor segment (e.g., polysulfone block segment in Example 1) can mix with a matrix-forming polymer (e.g., hydrophobic polymer) to form a polymer matrix. The bond between an anchor segment and an active surface segment may be literally a single covalent bond, or may be a linking moiety, such as an ether linkage (-O-), an amide, ester, or sulfonamide linkage, a monomer or any other organic moiety which does not adversely affect either solvent quality of the casting solution or

membrane formation (e.g., -N(R²)-(SO₂)-C₆H₄- and -N(R²)-(C=O)-C₆H₄-).

The term "active surface segment moiety" means a portion of a block copolymer segment which is present on, or extends above, the active surface of a polymer

article. An active surface segment moiety may be

attached to the polymer article at one end (with a second end extending "free" above the active surface) or it may be attached at both ends, as a "loop" appearing on, or extending above, the active surface. An active surface segment moiety has a property different from the bulk or matrix polymer, such as hydrophilicity, chirality, or a specific reactivity or affinity. Active surface segment moieties and presentation thereof are further addressed in the Detailed Discussion section below.

The term "alkyl" includes straight-chain groups such as methyl, n-hexyl, nonyl, tetradecyl, and icosyl; branched groups such as isopropyl, isopentyl, neopentyl, tert-pentyl, 4-ethyl-5-methyloctyl, and 4-isopropyl-5-propyl-nonyl; and cyclic alkyl groups such as

cyclopropyl, cyclopentyl, and 2-methyl-4-ethylcyclohexyl.

The term "bivalent radical" means a structural moiety with two free valences. The bivalent radical is bonded to two other moieties at the sites of the two valences. When bivalent formulas are provided, the following convention should be noted. For example, in formula (I) R-(OCH₂CH₂)_n-X-Y, X can be -Z¹-(OAr¹OAr²)_m-, wherein Z¹ is -N(R²)-(SO₂)-C₆H₄-. The left-terminal atom of X (i.e., the nitrogen atom of Z¹) is bonded to the right-terminal carbon atom of R-(OCH₂CH₂)_n-. Similarly, the right-terminal carbon atom of X (carbon of rightmost Ar²) is bonded to the left-terminal atom of Y. Note that Z² moieties are the same as Z¹ moieties except that the orientation of these bivalent moieties has been

horizontally reversed or flipped. This relationship is also observed in the use of (oxyethylene) and

(ethyleneoxy). Scheme I provides additional examples of bivalent radicals.

The term "perfluoroalkyl" means fully-fluorinated straight-chain carbon chains, such as trifluoromethyl and pentafluoroethyl. Perfluoroalkyls can be generalized by

C_nF_2n+1.

The term "hydrophilic" as in "hydrophilic active surface" means the same as wettable, or capable of forming at least some hydrogen bonds with water by means of polar atoms or groups of atoms. Hydrophilicity can be measured macroscopically by measuring, e.g., water contact angle, permeability, solvent flux, and solute rejection. Even after being dried, a spontaneously wettable surface requires little or no additional

surfactant or humectant. Certain polymer articles which include the disclosed block copolymers are spontaneously wettable (see, e.g., Example 3).

The term "weight percent" as used above to describe a casting solution means, for example, the weight of a component (e.g., block copolymer, solvent, matrix polymer, or additive, if any) divided by the total weight of the casting solution and then multiplied by 100.

Throughout this disclosure, all numerical ranges (e.g., ratios, temperatures, weight percents, and integer values of m, n, p, and so on) are understood to be inclusive.

The polymer articles disclosed herein are useful in aqueous separation processes such as microfiltration, ultrafiltration, dialysis, osmosis, reverse osmosis, ion exchange, or electrodialysis, or a combination thereof. Applications include water treatment, cell culturing, artificial organs, and food processing.

Other features and advantages of the present invention will be apparent from the following detailed description, and also from the appending claims. Detailed Description of the Invention

One aspect of the invention features a block copolymer used to make a porous polymer article having a plurality of active surface block segment moieties on the active surface of the article, wherein the active surface block segments are covalently bound to, and yet have properties different from, the interior anchor block segments of the article. The invention includes the porous polymer article, and a method of making it.

In some embodiments of the block copolymer having formula (1) described in the Summary section, each Q moiety is OAr¹. One example is a block copolymer of formula (2):

R-(OCH₂CH₂)_n-X-Y (2) R is C_1-20 alkyl (e.g., C_6-20 alkyl), C_7-20 alkylaryl,

C_7-20 arylalkyl, or C_1-20 perfluoroalkyl (e.g., C_6-20 perfluoroalkyl). The value of n is between 20 and 500

(e.g., between 20 and 400, or between 20 and 300). X is -Z¹-(OAr¹OAr²)_m- or -(OAr²OAr¹)_m-. Y is hydroxy, -(OAr³O)-Z²-(CH₂CH₂O)_p-R¹, or -(OAr⁴O)-(CH₂CH₂O)_p-R¹. Z¹ is

selected from -N(R²)-(SO₂)-C₆H₄- and -N(R²)-(C=O)-C₆H₄-, R² being C_1-12 alkyl or C_6-20 aryl. Z² is selected from -C₆H₄-(SO₂)-N(R³)- and -C₆H₄-(C=O)-N(R³)-, R³ being C_1-12 alkyl or C_6-20 aryl. R¹ is C_{1- 20} alkyl, C_7-20 alkylaryl, C_7-20 aryl-alkyl, or C_{1- 20} perfluoroalkyl. For example, each of R¹ and R is selected from lauryl, myristyl, palmityl, stearyl, cetyl, methyl, phenyl, octylphenyl, nonylphenyl, and perfluoroalkyl, or any of possible combinations thereof. In certain embodiments, R and R¹ are the same. Each of Ar¹ and Ar³ is independently selected from 1,4-phenylene, 1,3-phenylene, naphthyl-1,4-diyl, naphthyl-1,5-diyl, 4,4'-biphenylene, diphenyl ether-4,4'-diyl, diphenylthioether-4,4'-diyl, diphenylisopropyl-idene-4,4'-diyl,

diphenylhexafluoroisopropylidene-4,4'-diyl,

diphenylalkylene-4,4'-diyl wherein alkylene is -(CH₂) -, q being 1, 3, 5, 7 or 9, p-terphenyl-4,4'-diyl, and bivalent radicals of binaphthalene, anthracene, and phenylnaph-thalene. Preferably, Ar¹ is

diphenylisopropylidene-4,4'-diyl or

diphenylhexafluoroisopropylidene-4,4'-diyl.

In certain embodiments, Ar¹ and Ar³ are the same. Each of Ar² and Ar⁴ is independently selected from diphenylsulfoxide-4,4'-diyl, diphenylsulfone-4,4'-diyl, diphenyl ketone-4,4'-diyl, and bivalent radicals of diphenyl-C_1-12 alkyl phosphine oxide and diphenyl-C_6-20 aryl phosphine oxide. Ar² is preferably diphenylsulfone-4,4'-diyl or diphenyl sulfoxide-4,4'-diyl. In certain embodiments, Ar² and Ar⁴ are the same. The value of m is between 1 and 250 (e.g., between 1 and 200, or between 10 and 250).

The value of p is between 20 and 500 (e.g., between 20 and 400, or between 20 and 300). In one embodiment, Z¹ is -N(R²)-(S0₂)-C₆H₄- and Z² is -C₆H₄-(SO₂)-N(R²)-. The weight ratio of (OCH₂CH₂):(OAr¹OAr²) + (OAr²OAr¹) is between 5:1 and 1:20, e.g., between 3:1 and 1:10. In some embodiments of formulae (2) and (3), R is not H; or Y is not OH; or R is not H and Y is not OH.

Another embodiment of the invention is a block copolymer of formula (1), wherein each of R and R¹ is H or C_{1- 10} alkyl, n is between 40 and 8,000, X is -[OAr²Q]_m, m is between 4 and 250, Y is -OAr⁴O-[BCH₂O]_p-R¹, and p is between 40 and 8,000, provided that one Q moiety is

[OCH₂E]_u,

u being between 40 and 8,000, and two Q moieties are selected independently from OAr¹. This embodiment has the formula (3):

R-[OCH₂A]_n-[OAr²Q]_m-OAr⁴O-[BCH₂O] -R¹ (3) In various embodiments of formula (3) , 80% - 100% of E moieties is CH₂ in one Q, and 80% - 100% of A moieties and B moieties combined is CH₂; at least two Q moieties are [OCH₂E]_u; each of R and R¹ is independently H or C_1-3 alkyl, e.g., independently H or methyl, or independently C_1-3 alkyl; 80% - 100% of Ar² and Ar⁴ is diphenylsulfone-4,4'-diyl; or 80% - 100% of Ar¹ and Ar³ is

diphenylisopropyl-idene-4,4'-diyl. In other various embodiments, up to 80 weight percent of the block

copolymer is polyethylene oxide homopolymer, or a

combination of polyethylene oxide homopolymer and

polyethylene oxide-polypropylene oxide copolymer (e.g., up to 20%, between 10% and 80%, between 10% and 60%, between 20% and 50%, or between 40 and 80%). In

additional embodiments, up to 80 weight percent of central block segment -[OAr²Q]_m- includes a polyethylene oxide block polymer or an ethylene oxide-propylene oxide block copolymer; or -[OAr²Q]_m- includes a moiety having a molecular weight between 2,000 Da and 200,000 Da, this moiety being a polyethylene oxide block, an ethylene oxide-propylene oxide block copolymer, or a polyethylene oxide-polypropylene oxide-polyethylene oxide block copolymer. In some embodiments, n, u and p are each independently between 1 and 10,000 (e.g., between 40 and 8,000, 40 (or 100 or 2,000) and 5,000; and m is between 1 and 500 (e.g., between 3 (or 4, 10, 25, or 50) and 500, 50 and 500, 125 and 200, and 100 and 250). In one example, n is between 100 and 5,000, u is between 100 and 5,000, p is between 100 and 5,000, and m is between 125 and 200.

Regarding the number of internal (or central) PEO or PEO/PPO blocks and the run length of -(OAr²OAr¹)_m- or -(OAr²OAr¹)_m- (e.g., polysulfone) repeating units, the following general guidelines are provided. For materials prepared with an equivalent weight fraction of PEO, the number of internal PEO blocks will be inversely

proportional to the molecular weight of the PEO employed. For example, the number of PEO repeating units in a given block copolymer formed with a 10,000 g/mole PEO-diol is greater than the number of PEO repeating units in a block copolymer formed with a 35,000 g/mole PEO-diol. At the same time, the run length of PSF repeating units will increase as the molecular wegiht of the PEO-diol

increases.

The disclosed block copolymers (e.g., formulae (1) (2)) are first described generally by their relationship and function in a method of making porous polymer

articles. These articles (e.g., flat sheet or hollow fiber membranes) are formed by a wet-casting method.

Briefly, a casting solution is cast into a liquid

coagulation medium. A casting solution includes a block copolymer (e.g., A-b-B), a matrix-forming (or bulk) polymer (B'), and a solvent. According to the invention, diblock copolymer A-b-B includes a first block segment A which has a greater affinity for the coagulation medium than for the casting solution solvent, and a second block segment B which can mix with a desired matrix-forming polymer B'. The coagulation medium is a nonsolvent with respect to the matrix-forming polymer, i.e., the

coagulation medium does not dissolve the matrix-forming polymer. B and B' have an affinity for each other that results in mixing. Mixing includes physical

entanglement, co-crystallization, ionic interactions, electron donor-acceptor interactions, intermolecular actions such as hydrogen bonding and van der Waals interactions, and combinations thereof.

These aspects of the invention are based, in part, on the discovery of the following. During membrane formation, portions of the first block segment A (which has a greater affinity for the coagulation medium) localize at the interface between the coagulation medium and the casting solution solvent. Meanwhile, the second block segment B mixes with the matrix-forming polymer B' to form a polymer matrix. Although portions of the first block segment are localized on the active surface of the polymer article, the first and second block segments remain covalently-bonded to each other. Thus, the first block segment is covalently bound to the second block segment which, in turn, is mixed with or anchored to the matrix-forming polymer. The resulting polymer article, therefore, has an organized structure with portions of active surface segments present across the active surface of the article.

Any portion or moiety of a block segment may be present on the active surface of an article; surface presentation of the entire segment is not required.

Thus, where a block copolymer has a PEO block - (OCH₂CH₂)₂₀₀-, a PEO block segment moiety could be 50%, 35%, or 10%, or more, or less, of the 200-monomer length. It is possible that a relatively long single block segment gives rise to two or more active surface segment moieties which are connected to each other by a portion of the block segment that is not presented at the

surface. However, the design of the disclosed block copolymers favors presentation of one active surface segment moiety per block segment. Furthermore, in certain embodiments the active surface segment moieties are uniformly present across the active surface of the article. The uniformity (i.e., more or less even or average distribution of active surface segments) can be measured by methods such as X-ray photoelectron

spectroscopy. In certain embodiments which include PEO, the density of active surface segment moieties (i.e., PEO moieties) is sufficient to impart macroscopically-detectable hydrophilicity to the active surface (e.g., low water contact angle). A plurality of active surface segments (e.g., membrane-integrated or covalently-bonded hydrophilic moieties) means two or more active surface segments to create an active surface with the desired property or properties, such as degree of hydrophilicity. The above descriptive principles encompass block

copolymers and membranes formed therefrom, wherein the block copolymer is a diblock (A-b-B), a triblock (e.g., A-b-B-b-A or A-b-B-b-C, where C has a higher affinity for A and the coagulation medium, than for B and the casting solution solvent), a tetrablock, etc., or combinations thereof.

A specific example is now provided. One of the disclosed casting solutions includes a poly(ethylene oxide)-b-polysulfone-b-poly(ethylene oxide) triblock copolymer,

a hydrophobic (matrix-forming) polysulfone polymer, and N-methylpyrrolidinone as a casting solution solvent.

This triblock copolymer includes (1) a hydrophobic polysulfone (PSF) block segment which is miscible with a hydrophobic matrix-forming polymer which may be the same (PSF) or different, between (2) two terminal hydrophilic poly(ethylene oxide) (PEO) block segments which have a greater affinity for an aqueous coagulation medium containing water than for N-methyl-pyrrolidinone, the casting solution solvent. In this example, the miscible PSF block segment anchors the entire triblock copolymer to the PSF polymer matrix (e.g., membrane). The

hydrophilic active surface PEO moieties are presented at the active surface of the membrane, and yet the PEO block remains covalently bonded to the PSF membrane matrix.

Note that the active surface moiety (here, the PEO) is integral to the block copolymer, and is incorporated, via the casting solution, into the membrane during formation. In other words, the surface of a polymer article made according to the invention requires neither reactive functional groups nor subsequently derivatized functional groups to increase surface hydrophilicity.

A polymer article containing one or more disclosed block copolymers has improved performance. For example, addition of a PEO-b-PSF-b-PEO triblock copolymer improves performance by increasing water permeability and protein recovery (resistance to protein adsorption), and

decreasing cytochrome-C rejection. One of the unexpected results of the disclosed block copolymers is the superior performance of membranes made therefrom when treated with only a fraction (e.g., a 5% solution of glycerol) of the usual amount of surfactant or humectant. According to the invention, hydrophilic active surface segments are permanently integrated into the polymer during polymer formation. Therefore, no further functionalization or derivatization is required, which shortens the

manufacture time and simplifies the machinery necessary to make the disclosed polymer articles. The hydrophilic surface results from membrane-integrated active surface segments which are covalently-bonded to the polymer matrix during membrane formation. When such a polymer membrane is used in a separation process, both the retentate and filtrate are therefore free of certain contaminants. Examples of contaminants include chemical residues associated with derivatized membranes

(reactants, work-up reagents, solvents); and leached or deposited materials associated with membranes with non-covalently bonded coatings. More specific descriptions are provided immediately below.

Block Copolymers

One aspect of the invention relates to a block copolymer having the formula (1) or (2) as described in the Summary. According to the invention, a block

copolymer generally includes two block segments with different properties. For example, in one aspect, an amphiphilic block copolymer has a hydrophilic block segment and a hydrophobic block segment. Hydrophobic and hydrophilic are relative terms well-known to those in the art. Hydrophilic polymers include peptides,

dialkylacrylamides, and preferably poly(ethylene oxide) (PEO). The chain-terminating (i.e., endcapping)

monofunctional PEO or PPO is commercially available in a variety of molecular weights. PEO or PEG is available in a range between 0.4 kD to 1,000 kD, such as 1.0 kD to 600 kD, or 4 kD to 200 kD.

Block copolymers having lower molecular weight PEO segments generally decrease the glass transition

temperature of polysulfones, and are therefore suitable as internal plasticizers. Block copolymers having higher molecular weight PEO segments have a greater tendency to undergo phase separation, and are therefore suitable to prepare thermoplastic elastomers. Certain embodiments include PEO in the higher available molecular weight ranges. Hydrophobic polymers include

polyalkylmethacrylates, polyphenylene, and preferably polyacrylonitrile, polyvinyl halides, polyvinylidene halides, polyimide, polyamide, polyetherimide, and even more preferably poly(arylethers) such as homopolymers of -(OAr¹OAr²)- (e.g., wherein Ar² is polyether sulfone or polysulfone) . Halides include bromides, iodides, and preferably fluorides and chlorides.

The invention contemplates the use of combinations of diblock and triblock copolymers, and combinations of different block copolymers, e.g., nonylphenyl

poly(oxyethylene)-b-poly(aryl ether sulfone)-b-poly(ethyleneoxy)phenylnonyl and perfluoroalkyl

poly(oxyethylene)-b-poly(aryl ether sulfone), to make porous polymer articles such as flat sheet or hollow fiber membranes. Examples of pairs of diblock and corresponding triblock copolymers include methyl

poly(oxyethylene)-b-poly(aryl ether sulfone) and methyl poly(oxyethylene)-b-poly(aryl ether sulfone)-b-poly(ethyleneoxy)methyl; phenyl poly(oxyethylene)-b-poly(aryl ether sulfone) and phenyl poly(oxyethylene)-b-poly(aryl ether sulfone)-b-poly(ethyleneoxy)phenyl;

stearyl poly(oxyethylene)-b-poly(aryl ether sulfone) and stearyl poly(oxyethylene)-b-poly(aryl ether sulfone)-b-poly(ethyleneoxy) stearyl; cetyl poly(oxyethylene)-b-poly(aryl ether sulfone) and cetyl poly(oxyethylene)-b-poly(aryl ether sulfone)-b-poly(ethyleneoxy)cetyl; lauryl poly(oxyethylene)-b-poly(aryl ether sulfone) and lauryl poly(oxyethylene)-b-poly(aryl ether sulfone)-b-poly(ethyleneoxy)lauryl; octylphenyl poly(oxyethylene)-b-poly(aryl ether sulfone) and octylphenyl

poly(oxyethylene)-b-poly(aryl ether sulfone)-b-poly(ethyleneoxy) phenyloctyl; nonylphenyl

poly(oxyethylene)-b-poly(aryl ether sulfone) and

nonylphenyl poly(oxyethylene)-b-poly(aryl ether sulfone)-b-poly(ethyleneoxy)phenylnonyl; and perfluoroalkyl poly(oxyethylene)-b-poly(aryl ether sulfone) and

perfluoroalkyl poly(oxyethylene)-b-poly(aryl ether sulfone)-b-poly(ethyleneoxy)perfluoroalkyl.

Note that in formula (2), X is -Z¹-(OAr¹OAr²)_m- or -(OAr²OAr¹)_m-. In other words, in the second bivalent formula, there are m -(OAr²OAr¹)- units. An alternative expression for this block is -(OAr² _iOAr¹ _i)_i-, where i is 1 to m. Similar expressions exist for the other block segments involving n and p. The methods of making a block copolymer permit wide variation, such that Ar¹ and Ar² in one -(OAr²OAr¹)- unit may differ from the Ar¹ and Ar² in another (e.g., adjacent) -(OAr²OAr¹)- unit. In other words, each of Ar¹ ₁ and Ar¹ ₂ is independently selected. The term "each of Ar¹ and Ar³ is independently selected from" is therefore understood to encompass such "mixed" blocks. However, it is preferred that 90% of the m units are the same.

Using the methods disclosed in Examples 1 or 2, the overall weight percent of PEO could be limited by the need for sufficient polysulfone to precipitate the polymer product in water. However, the product can be isolated by other means, such as dialyzing the reaction mixture against water to remove smaller molecular weight impurities and evaporating the remaining water; by using solvent mixtures which are less polar than water to cause precipitation. The wt % of PEO can also be increased by decreasing, or even omitting, bisphenol A and linking the bifunctional segments by bischlorophenyl sulfone

directly.

In a second aspect of the invention, one or more internal segments of the block copolymer is PEO or

PEO/propylene oxide copolymers. Such internal segments are generally formed with the corresponding difunctional PEG, which is commercially available in a wide variety of intermediate and high molecular weights (kD) such as l, 2, 4, 8, 10, 12, 18.5, 35, 50, 80, and 100. Random difunctional PEO/propylene oxide copolymers, and diblock and triblock copolymers are commercially available in many molecular weights between 1,000 and 1,000,000 Da. Copolymers and block copolymers are preferably between 2,000 and 20,000 Da. Combinations of the above include: two or more different molecular weight PEGs (Example 9); random PEO/PPO (Example 10); and the same or different molecular weight PEGs (internal bifunctional) and PEOs (chain terminating) (see Examples 11 and 12).

Proportions of these combinations can be equal or

unequal.

In one embodiment, the total weight percent of polyethylene oxide block and polyethylene oxide- polypropylene oxide random copolymer is up to 80 weight percent (e.g., between 10 and 60 weight percent of the block copolymer, or between 10 and 40% weight percent). For a given total weight percent of PEO block and PEO/PPO random copolymer, such as 40 weight percent, a variety of combinations of PEO block and PEO/PPO random copolymer are possible. For example, contributions of PEO block and PEO/PPO random copolymer, respectively, include: 0% and 40%, 10% and 30%, 40% and 0%, 25% and 15%, 20% and 20%, and so on. Analogously, other pairs or multi- component combinations from among PEO block, PPO block, PEO/PPO random copolymer, and PEO-PPO-PEO triblock, can constitute up to 80 weight percent of a disclosed block copolymer.

Internal segments of PEO increase the overall weight percent of PEO, and in conjunction with chain-terminating PEO groups, produce a block copolymer having more uniform properties which are suitable for

thermoplastic applications, such film formation, melt- extrusion, and molding. Sampled block copolymers of formula (3) had melting points of 150°C - 170°C and degraded at temperatures around 300°C. Based on melting point, DSC, and glass transition measurements, the processing windows for block copolymers of formula (3) are appropriate for a range of applications, especially as interfacial adhesion agents, and as dispersion, or adsorption agents which improve mechanical strength.

Block copolymers of formula (3) are particularly suitable for making thermoplastic polymeric articles. The method of making these articles includes (a) blending and/or co-melting a block copolymer of formula (3) with a compatible (e.g., high-melting) thermoplastic such as polysulfones, polyaryl ethers, polycarbonates, and nylons; or (b) co-mixing a block copolymer of formula (3) with an incompatible polymer or with an organic additive or inorganic such as titania or silica. The blended, co-melted, or co-mixed material is then injection molded, extruded, or thermo-formed under pressure, and cooled to a rigid or semi-rigid state.

Higher weight percents of PEO generally increase the thermoplastic elastic properties of the product.

Polymers having 30 wt% (Example 11), 50 wt% (Example 12), and 80 wt% (not shown) have been made. Thermoplastic elastic properties can be easily measured by methods known to those in the art, such as melting point, DSC, and glass transition temperatures.

Synthesis of a Block Copolymer

The invention is based, in part, on the design of a block copolymer consistent with the principles

described above. After discovery of these principles, synthesis of a specific block copolymer is

straightforward, and is accomplished by numerous routes known or easily determined by those in the art. Two exemplary synthetic routes are provided here.

Scheme II illustrates the preparation of a

poly(oxyethylene)-b-polysulfone-b-poly(ethyleneoxy) triblock copolymer by condensation. First, a PEO chain-terminating monomer is reacted with a reactive 4-fluorophenyl sulfonamide end group. Second, the PEO chain terminating monomer is reacted with 4,4'-isopropylidene diphenol and bischlorophenyl sulfone.

Using mixtures of dihydroxy or dihalo reagents results in mixed-component block copolymers.

Scheme III illustrates an alternative preparation, wherein a PEO-block alcohol, an aryl diol, and a reactive difunctionalized (e.g., dihalo, dinitro, or halo-nitro) aryl reagent (e.g., bischlorophenyl sulfone) are reacted to form a combination of diblock and triblock copolymers. Reacting the three reactants in stoichiometric

proportions where the ratio of PEO:diol: sulfone is

2n:m: (n+m) yields a high rate of endcapping. In other words, high-molecular weight triblock copolymers such as PEO-PSF-PEO are predominantly formed. On the other hand, the ratio of PEO:diol: sulfone can be q:r:r. Thus

reacting equal amounts of the difunctional reactants (e.g., diol and sulfone) and some amount of endcapping reactant (e.g., polyethyleneoxy or polyethylene glycol) generally yields a mixture of triblock copolymer, diblock copolymer, and homopolymer polysulfone. One embodiment includes 10 - 80 weight percent; another includes 15 - 40 weight percent of PEO. The latter embodiment is

particularly suitable to form hollow fiber membranes for dialysis.

Polymer Article

One aspect of the invention is a porous polymer article with a covalently-bonded hydrophilic moiety present on its active surface as described in the summary section. The porous polymer article includes (i) a hydrophilic-hydrophobic diblock copolymer, a hydrophilic- hydrophobic-hydrophilic triblock copolymer, or a

combination thereof, and (ii) a hydrophobic polymer. A hydrophobic moiety of the diblock or triblock copolymer mixes with the hydrophobic polymer to form a polymer matrix. For example, the polymer article has up to 80 weight percent of one or more block copolymers (e.g., in weight percents, between 0.01 and 80, between 5 and 50, and between 15 and 40) . In one embodiment, the article includes a diblock copolymer (i.e., Y is hydroxy); in another embodiment, the article includes a triblock copolymer (Y is disclosed or undisclosed moiety that is not hydroxy).

Synthesis of a Polymer Article by Phase Inversion

Formation of polymer articles (e.g., flat sheet or hollow fiber membranes) with a disclosed block copolymer is adapted from methods known in the art, provided that the casting solution solvent, the coagulation bath medium, the temperature, and other conditions known and understood in the art are selected in a manner consistent with the invention as described above. One aspect of the invention relates to a method of making a porous polymer article with enhanced hydrophilicity including three steps as described in the Summary section. However, the invention is also based, in part, on the discovery that after a polymer article is formed, thermally annealing the article enhances the already-superior or desirable performance properties.

The first step in preparing a polymer article is providing a casting solution. The disclosed block copolymers are used to prepare a casting solution which includes a block copolymer, a matrix-forming polymer, and a polar aprotic organic solvent. In general, a casting solution includes up to 80% solids, i.e., the sum of block copolymer and matrix polymer is less than or equal to 80% (e.g., less than or equal to 50, 40%, or 35%; or between 5% and 25%). A person of ordinary skill in the art can easily determine whether, and how much, heating is necessary and appropriate to form an acceptably homogenous casting solution.

Specific examples of block copolymers are described above. A casting solution may include either a single block copolymer or a combination of two or more block copolymers in any desirable proportion. A casting solution includes between 0.1 and 50 weight percent

(e.g., 5 - 35 or 10 - 30 weight percent) of a disclosed block copolymer, or a combination of disclosed block copolymers.

A hydrophobic matrix-forming polymer is a rigid block polymer known in the art, or a nonblock polymer such as a homopolymer of bischlorophenyl sulfone. The weight percent of the hydrophobic polymer is 0.1 - 30 weight percent (e.g., 5 - 20 weight percent) of the casting solution. Examples of hydrophobic polymers include the group consisting of polyacrylonitrile, polyvinyl halide, polyvinylidene halide, polyimide, polyetherimide, and polyamide, and polymers of - (OAr¹OAr²)-, or a copolymer thereof. In one embodiment, the hydrophobic polymer is a polymer or copolymer of - (OAr¹OAr²)-, wherein Ar² is, e.g., diphenylsulfone-4,4'- diyl.

The casting solution includes between 40 and 95 weight percent (e.g., between 50 and 90 weight percent, or between 65 and 90 weight percent) of a solvent or solvent system. Suitable polar aprotic organic solvents include N-methylpyrrolidinone (NMP), dimethylformamide, dimethyl-acetamide, 4-butyrolactone, and a solvent system thereof. For example, a solvent system may include toluene or water, provided the solvent quality is

maintained. In one embodiment, the polar aprotic solvent is N-methyl pyrrolidone. In addition to a block copolymer, a hydrophobic polymer, and a solvent, other additives may be included, provided that the adjusted solvent quality is not so adversely affected that precipitation occurs. Examples of such solvent quality-adjusting additives include a hydroxyl-containing reagent such as polyethylene glycol (commercially available in molecular weights such as 300, 400, 600, 900, 1000, 1,500, 2,000, 4,000, 8,000, 10,000, 12,000, and

18,500), water, and low molecular weight alcohols (e.g., C_1-8 alcohols); and soluble salts such as lithium

chloride, present in 0.1 - 7 weight percent, e.g., 2 - 6 weight percent. For example, the casting solution may further include 5 - 30 weight percent (e . g. , 10 - 28 weight percent) of a hydroxyl-containing reagent selected from polyethylene glycol (e.g., molecular weight of 300, 400, or 600), water, and C_1-8 alkanols. Where the block copolymer contains higher molecular weight blocks (e.g., high molecular weight PEG ), higher molecular weight PEG or alkanols as a casting solution additives can be used without causing phase separation. Additives also include those additives well-known in the art such as small amounts of colorants. Coagulation temperatures range from 18 - 90°C (e.g.,

18 - 50°C).

Specific casting solutions are found in the examples below. Disclosed casting solutions include (in weight percents): 10 weight percent block copolymer, 10 weight percent polysulfone, and 80 weight percent polar aprotic solvent; 10 weight percent block copolymer, 15 weight percent polysulfone, 25 weight percent

polyethylene glycol, and 50 weight percent polar aprotic solvent; or 15 weight percent block copolymer, 5 weight percent polysulfone, and 80 weight percent polar aprotic solvent. Some casting solutions consist of disclosed block copolymers, polysulfone, NMP, and a soluble salt such as lithium chloride.

A person of ordinary skill in the art can easily determine the composition of a suitable nonsolvent coagulation bath medium, based on the block copolymer, particularly the block segment to be presented on the active surface, the casting solution solvent, the matrix polymer, and the desired pore structure of the polymer article. In general, the solvent and solvent additives should be soluble in the coagulation medium, and the hydrophilic matrix polymer should precipitate in the coagulation medium. Examples of coagulation media include of NMP and water in combinations such as 0% NMP-100% water, 50% NMP-50% water, 70% NMP- water, and 80% NMP-20% water.

In one example of making a polymer article, a casting solution was spread onto sheets of nonwoven polypropylene fabric taped to glass plate supports and immersed in a coagulation medium of reverse osmosis- processed water at room temperature. After

precipitation, the membrane including the integrated support sheet was placed in a second water bath to remove residual solvent (NMP) and pore former (e.g.,

polyethylene glycol or PEG). The rinse water was

repeatedly changed for 24 hours to improve diffusion.

Then the membranes were placed in 70% v/v glycerol solution for 24 hours, placed between two sheets of blotting paper, dried at room temperature, and stored in air-tight bags.

Although thermal annealing is not necessary to produce a porous, polymer article which includes a block copolymer of the invention, such treatment is preferable, since it was found to enhance the hydrophilic or wetting properties of polymer articles of the invention to an unexpected degree in an unexpected way. In general, autoclaving increases the membrane molecular weight cut-off. However, when membranes of the invention were thermally annealed, the molecular weight cut-off was found to stay the same or even decrease. For example, it is believed that in membranes containing PEO, thermal annealing in the presence of water enhances the degree of PEO presentation, and the overall distribution of PEO active surface segments.

According to the invention, thermal annealing generally occurs in the presence of water (e.g., a water bath or an autoclave). In one embodiment, the thermal annealing step includes heating the article in an

autoclave at a temperature between 95 and 130°C (e.g., between 100 and 125°C). In another embodiment, the thermal annealing step includes heating the article at a temperature between 40 and 90°C (e.g., between 45 and 75°C) . The annealing temperature and annealing time generally have an inverse relationship. In one example, thermal annealing included heating the article at about 120°C for approximately 30 minutes. In another example, thermal annealing was performed at about 50°C for

approximately 24 hours. In each case, the hydrophilicity of the thermally annealed membrane after being dried was measurably increased when compared to a membrane of the same composition after being dried (see Tables III, VI, and VII). Thermal annealing drastically improves the useful life of the membrane by increasing the wettability or hydrophilicity of a membrane even after all liquid solvent has been removed (dried).

Polymer articles were characterized by several methods known to those in the art. Such methods include characterization by Fourier-transformed infrared

spectroscopy (FTIR); solid state proton and ¹³C NMR (with a paramagnetic relaxation agent such as Cr(acac)₃ to determine organization of the block copolymer at the membrane interface; porometry and scanning electron microscopy (SEM) to determine morphology (homogeneity, porosity); measurement of contact angle and bubble point to determine hydrophilicity; gel permeation

chromatography (GPC) to determine molecular weight M_n; and differential scanning calorimetry to determine T_g. Characterization also included performance

characteristics such as water flux, solute flux, and solute rejection. Additional parameters include

resistance to protein adsorption, sponge thickness, top pore size, finger length, and casting solution viscosity. These parameters are measured by methods known to those in the art.

Extruded. Molded, or Coated Articles

Another aspect of the invention is a thermoplastic (e.g., extruded, molded, or moldable) polymer article which has been molded, extruded, or otherwise formed from a composition which includes (i) one or more block copolymers of formula (1) or (3), and (ii) an inorganic additive such as titania or silica; a thermoplastic polymer, such as a polyaryl ether, a polycarbonate, or a nylon; or other organic additives; or a combination thereof. In general, the thermoplastic article has at least one surface capable of phase-separation, surface adhesion, or interfacial interaction as a result of the block copolymer of formula (1) or (3). The invention therefore features a polymeric article formed by either the direct extrusion or the injection molding of a composition containing a block copolymer of formula (3), e.g., wherein the composition further contains an

inorganic additive, or wherein said composition further contains a thermoplastic polymer, or a combination thereof. Thermoplastic films and molded forms can be formed with block copolymers having generally higher molecular weight percents of PEO relative to the cast polymers.

Solvents include polar aprotic solvents and other

appropriate solvents known to those in the art, such as DMSO, DMF, THF, MEK, halocarbons (e.g., freon or

chloroform), and NMP. The PEO segment(s) of the

disclosed block copolymers provide increased

hydrophilicity and lubricity, and therefore the disclosed block copolymers can act as internal mold release agents. Hydrophilicity is desirable for biocompatibility or hemocompatibility, including improved lubricity for manufacturing, demonstrated by ease of release of an injection molded article from the mold. Lubricity or hydrophilicity are desirable for biomedical devices, particularly invasive or insertable devices such as urogenital and ocular devices, such as contact lenses, catheters, and other prosthetic devices. In addition, hydrophilic packaging films are more resistant to

fogging. Hydrophilicity is demonstrated by, for example, water contact angle measurements.

Without further elaboration, it is believed that the present invention can be utilized to its fullest extent. The following examples, therefore, are to be construed as illustrative, and not limitative, of the remainder of the disclosure.

Example 1

A 50% PEO/50% PSF block copolymer (5 kD) was synthesized as follows. Reflux apparatus was purged with argon. Methyl poly(oxyethylene) with a terminal hydroxyl (200 g, 0.04 moles), bisphenyl disopropylidene-4,4'-diol (Bisphenol A, 114.145 g, 0.5 moles), and bischlorophenylsulfone (149.328 g, 0.52 mole) were added to 600 mL N-methylpyrrolidinone and 150 mL toluene and potassium carbonate (143.5 g, 1.04 moles). The reaction mixture was slowly heated over 0.5 hours until an azeotrope reflux was reached (about 160°C). After an additional hour of reflux, 10.0 mL water was collected via azeotrope and 50 mL toluene was removed. The temperature was raised to 175°C and an additional 3.5 mL water was collected. Azeotrope ceased after an additional 1.75 hours, 80 mL toluene was removed, and the temperature was raised to 190°C. After polymerization for 7.5 hours, the heat source was removed, and the reaction vessel was cooled to room temperature. The product precipitated in a solution of 100 mL concentrated hydrochloric acid and 10 L water. After repeated filtration and extraction with water, the polymer product was allowed to dry in ambient conditions overnight, and then at 50°C under vacuum (1-5 mm Hg).

Example 2

A casting solution containing 5.0 weight percent PEO-PSF-PEO (a PEO:PSF::30:70 block copolymer), 13.5 weight percent polysulfone, 6.5 weight percent

polyethylene glycol (M.W. 400), and 75.0 weight percent N-methyl pyrrolidinone was prepared. The solution was prepared in a glass jar and placed on a roll mixer for 24 - 48 hours until a single phase solution was obtained. Flat sheet membranes were prepared by casting a 0.015 inch coating of the casting solution onto a glass plate or a nonwoven polypropylene support (Freudenberg). The coated support was immersed in a coagulation water bath until precipitation. After additional extraction with water, the membranes were immersed in a glycerol/water solution for a minimum of 1 hour. One group of membranes were dried in ambient conditions. A second group of membranes, after drying in ambient conditions, were immersed in a water bath and thermally annealed in an autoclave at 121°C for 30 minutes and allowed to dry at ambient conditions. A third group of membranes was simply removed from the extraction bath and allowed to dry at ambient conditions. The resulting membranes were cut into discs having a 47 mm diameter and evaluated by filtering 20 ml of a 0.1% Cytochrome-C solution

therethrough until a 50% volume reduction was achieved.

Example 3

A casting solution containing 10.0 weight percent PEO-PSF-PEO (a PE0:PSF::30:70 block copolymer), 10.0 weight percent PSF, 5.0 weight percent polyethylene glycol, and 75.0 weight percent N-methyl pyrrolidinone was prepared. Membranes were prepared according to Example 2 except the above casting solution was used.

The block copolymer membranes of Example 3 were also tested for water permeability and filtration. After extraction with water, the membranes were thermally annealed by heating in a water bath at 121°C for 30 minutes in an autoclave. The membranes were then dried at room temperature, and compared with two polysulfone membranes made of 15% PSF, 10% PEG MW 400 and 75% NMP; one dried with glycerol (PSF 1) and one dried without glycerol or surfactant (PSF 2) . The data indicate that the disclosed membranes, even when dry, spontaneously wetted with water (see Table I) . In contrast, to impart wettability to the conventional polysulfone membranes, treatment with a surfactant was required (e.g.

glycerol). The results also indicate that the disclosed membrane had a 30-50 kD molecular weight cut-off, and had a solute recovery rate superior to the reference

polysulfone membranes.

Example 4

A casting solution containing 15.0 weight percent PEO-PSF-PEO (a PEO:PSF::30:70 block copolymer), 5.0 weight percent of PSF, 80.0 weight percent of N-methyl pyrrolidinone was prepared. Membranes were prepared according to Example 2 except that the above casting solution was used and the mixture was coagulated in a 3 : 1: :NMP:water bath. After coagulation, the membranes were placed in a secondary extraction bath of pure water for a minimum of 12 hours and dried under ambient

conditions.

Membranes obtained via Example 3 were

characterized by observation via SEM and solid state NMR, and by measurement of water permeability, solute permeability, and protein adsorption. The NMR results are presented below in Table II.

The NMR results suggest the organization of the block copolymer at the membrane surface. The distinct relaxation times for PEO and PSF indicate two distinct physical domains within the membrane. After treatment with a D₂O solution of paramagnetic agent chromium (111) acetylacetonate (Cr(acac)₃), the relaxation associated with PEO was suppressed while the relaxation associated with PSF was unaffected. This is consistent with PEO being localized in domains accessible to the Cr(acac)₃ solution at the membrane surface, and PSF being localized in the interior membrane matrix.

Example 5

A casting solution for hollow fiber membranes containing 10.0 weight percent PEO-PSF-PEO (a PEO:PSF::30:70 block copolymer), 15.0 weight percent PSF, 25.0 weight percent polyethylene glycol (M_n 600) and 50.0 weight percent N-methyl pyrrolidinone was prepared.

Hollow fibers were formed from the casting solution by spinning the solution at 55°C at 100 feet per minute with nominal inner diameter of 200 μm and nominal outer diameter of 300 μm. The nominal wall thickness was 50 μm. The drop height, defined from the bottom of the spin nozzle to the level of the water in the coagulation bath, was 5 feet. The core solution was either pure water or a mixture of NMP and water. After collection on the take-up wheel, the fiber was extracted repeatedly in water. Post-treatment included soaking in various glycerol/water solutions ranging from 0 to 80% glycerol/water by weight, or thermally annealing the fiber in water for about 30 minutes at 120°C (autoclave). The fibers were then air dried at room temperature overnight.

Membranes obtained in Example 5 were characterized via SEM and were further characterized by measurement of the pre-foul NaCl and Vitamin B-12 permeability and the bovine serum ultrafiltration coefficient, K_uf . The wettability of fibers made from casting solutions with and without triblock copolymer present is in Table III. Spinning conditions for the casting solution without the triblock copolymer were identical to those given above. The performance of the fiber soaked in the 80% glycerin solution represents the maximum obtainable for a fully-wetted membrane in both cases. For membranes made from casting solution containing only PSF and PEG 600, the wettability is lost or the performance is reduced at all other glycerin concentrations tested. When no wetting agent was used (i.e., pure water) the fiber collapsed when dried overnight. Performance therefore could not be measured. In contrast, the fiber made from casting solution containing PSF, PEG 600 and the PEO-PSF-PEO triblock copolymer maintained wettability or performance for all glycerin concentrations, including 5%.

Furthermore, the autoclaved fiber containing no wetting agent also maintained wettability. Only the fiber that was air dried overnight with no wetting agent or

autoclaving post treatment showed a reduction in

performance and, thus, wettability. The use of the triblock copolymer in the casting solution greatly reduced or eliminated the need for glycerin as a wetting agent or a pore maintenance agent in hollow fibers.

Membranes from Example 5 are contrasted to a PSF membrane made of 22% polysulfone, PEG 600 and 48% NMP (see Table III).

The membrane of the present invention retains remarkable performance when treated with a low

concentration of glycerol whereas the conventional PSF membrane requires treatment with 80% glycerol for similar performance. More importantly, thermal annealing alone produces superior performance. Some flow is retained even when the disclosed membrane is merely air-dried. Treatment of the PSF-only membrane with 5% glycerol or autoclave can also be determined.

The solute rejection and protein recovery rate of membranes made according to Examples 2 and 3 were

calculated by measuring the concentration of the starting solution, the retained solution and the filtrate. Table IV shows the results thereof.

Scanning electron micrographs show that this polymer membrane is porous, with a homogeneous, spongy, and asymmetric cross section with a thickness between 180 and 200 μm. The pores range between 0.05 and 2.0 μm in diameter. Example 6

A survey of casting solution compositions incorporating PEO-b-PSF and polysulfone (Udel 3500) was made (see Table V). N-methyl pyrrolidinone was used as the solvent for all the formulations and a coagulation bath consisting of H₂O at 50°C. PEO-b-PSF can be used to formulate membranes whose molecular weight cutoff ranges from > 2,000 kD (i.e. 5% PMX30-5B13/5% PSF) to 20 kD (i.e. 10% PMX30-5B13/15% PSF). An asterisk (*) indicates that the membrane was tested at 55 psi, and the reported flux was normalized to 10 psi. The following abbreviations were used: BLDex = Blue Dextran, Mn ≈ 2,000 kD, BSA = Bovine Serum Albumin, Mn = 67 kD, Cyt-C = Cytochrome C, Mn = 12.4 kD. Solvent (NMP) formed the balance of each formulation. All were cast (8 mil) on nonwoven polypropylene fabric (Freudenberg) and

coagulated in H₂O at 50°C for 5 minutes, then removed for exhaustive extraction in H₂O. All membranes were dried from a glycerin solution. Reported rejections were calculated from the filtrated concentration for a single solute half reduction test.

Example 7

The effect of thermal treatments of a 10% PEO-b-PSF/10% PSF membranes was explored (see Table VI). As the temperature of the aqueous coagulation bath

increased, the H₂O flux increased and the recovery of Cytochrome-C increased (row 3, glycerin treated

membrane). The increasing recovery of Cyt-C reflected a decrease in adsorption of the protein. The effect of protein adsorption was much more easily seen for the smaller solute as it substantially passed through the membrane and was thus exposed to the full active surface of the membrane. The decrease in protein adsorption resulted from an enhanced surface enrichment of PEO active surface segments.

Membranes were also thermally treated after fabrication to improve the PEO surface enrichment (column 1, membrane 3845-52). Membranes which were placed in a water bath at 50°C for 24 hour, and then either air dried or dried from glycerin had a markedly improved Cyt-C recovery compared to the membrane which received no thermal post- treatment. This information supports the enhanced surface enrichment of PEO after thermal

annealing. Furthermore, the measurable flow and

rejection of the air dried membrane demonstrate the enhanced wettability of the thermally treated membrane. There was no measurable flow for the membrane which was not thermally treated. A more vigorous thermal treatment in a 120°C water bath for 30 minutes (autoclave) yielded a membrane with surprising qualities. In addition to improved protein recovery and a more open pore structure, this membrane fully recovered its water permeability without added glycerol or surfactant. In Table VI, block copolymer 3845-53 contained 22.2% PEO, and was 51.4 kD. Block copolymer 3791-16A1 contained 23.5% PEO, and was 56.6 kD.

Example 8

Reflectance spectroscopy provided a complementary measure of Cyt-C adsorption to the membrane (see Table VII). Increasing spectral absorbance indicated

increasing amounts of adsorbed protein.

Example 9

A l-L round bottom flask equipped with a

mechanical stirrer, a Dean-Stark trap, and a nitrogen purge was charged with 309.1 grams dipotassium carbonate and the following monomers: 32.3 grams 5,000 Da

monomethyl polyethylene glycol; 290.3 grams 10,000 Da polyethylene glycol; 162.8 grams bisphenol A; and 214.1 grams 4,4'-chlorophenylsulfone.

Under nitrogen flow, 600 ml toluene and 1500 ml N-methylpyrrolidone solvents were added. The flask was sealed with a rubber septa through which a thermocouple probe was inserted. Heating the reagent mixture with stirring to toluene reflux initiated the reaction, at about 155-160°C. Water-toluene azeotrope collected in the Dean-Stark trap, yielding a total of 26.0 mL water during 5 hours. Toluene was distilled from the system as the temperature was raised to 190°C to affect

polymerization. After 6 hours, polymerization was halted, and the mixture allowed to cool to room

temperature. Mixing with an excess of dilute HCl

neutralized the residual potassium carbonate and

precipitated a viscous polymer. After two extractions with fresh water, the recovered polymer was filtered and dried in a convection oven at 65°C to a constant weight.

Four additional block polymers were prepared as Example 9, substituting for polyethylene glycol of average molecular weight 10,000 Da, polyethylene glycols of 4000 Da, 8000 Da, 12000 Da, and 18500 Da,

respectively. Example 10

A polymer was prepared as in Example 9, with the following stoichiometry. A weight fraction of 40% of a random two-component PEO/PPO (5:1 ratio, MW 8750, Polyscience, Warrington, PA) was used. The two-component PEO/PPO (0.006 mole) was reacted with 0.2754 mole

bisphenol A, 0.2784 moles of bischlorophenylsulfone, and 0.8352 moles of potassium carbonate in 375 ml of NMP and 125 ml toluene. Example 11

A polymer was prepared as in Example 9, with the following stoichiometry. A weight fraction of 30% of a 1:2 ratio of a two-component polyethylene glycol

consisting of 0.0174 mole 10 kD PEG (Fluka Chemika,

Switzerland) and 3.87 × 10^-3 mole 5 kD polyethylene glycol monomethyl ether (Polyscience, Warrington, PA) was used. The two-component PEG (0.0387 mole) was reacted with 1.01 mole bisphenol A, 1.03 moles of bischlorophenylsulfone, and 3.09 moles of potassium carbonate in 1.5 liters of NMP and 600 ml toluene.

Example 12

A polymer was prepared as in Example 9, with the following stoichiometry. A weight fraction of 50% of a two-component polyethylene glycol consisting of 0.0290 mole

10 kD PEG (Fluka Chemika) and 6.45 × 10^-3 mole 5000 kD polyethylene glycol monomethyl ether (Polyscience) was used. The two-component PEG (0.0645 mole) was reacted with

0.713 mole bisphenol A, 0.745 moles of bischlorophenylsulfone, and 2.24 moles of potassium carbonate in 1.5 liters of NMP and 600 ml toluene.

Other Embodiments

From the above description, the essential

characteristics of the present invention can be

ascertained. Without departing from the spirit and scope thereof, various changes and modifications can be made to adapt to various usages and conditions.

For example, a tetrablock or pentablock copolymer including poly(ethyleneoxy) and a hydrophobic block segment such as but not limited to those described herein is also within the scope of the claims. Similarly, by adjusting the solvents and additives, a non-porous dense film may be made with the recited block copolymers. In addition, poly (ethyleneoxy) may be replaced by a

similarly hydrophilic polymer. Thus, other embodiments are also within the claims.

What is claimed is:

Claims

1. A block copolymer having the formula:

R-[OCH₂A]_n-X-Y wherein R is H, C_1-20 alkyl, C_7-20 alkylaryl, C_7-20

arylalkyl, or C_1-20 perfluoroalkyl;

each A is independently selected from CH₂ and CH(CH₃);

n is between 1 and 10,000;

X is -Z¹-(OAr¹OAr²)_m- or -(OAr²Q)_m-, Q being OAr¹ or [OCH₂E]_u, wherein m is between 1 and 500, each E is independently selected from CH₂ and CH(CH₃), and u is between 1 and 10,000; and

Y is hydroxy, -(OAr³O)-Z²-[BCH₂O]_p-R¹, or -(OAr⁴O)- [BCH₂O] -R¹, wherein each B is independently selected from CH₂ and CH(CH₃), and p is between 1 and 10,000;

wherein Z¹ is selected from -N(R²)-(SO₂)-C₆H₄- and -N(R²)-(C=O)-C₆H₄-, R² being C_1-12 alkyl or C_6-20 aryl;

Z² is selected from -C₆H₄-(SO₂)-N(R³)- and -C₆H₄- (C=O)-N(R³)-, R³ being C_1-12 alkyl or C_6-20 aryl;

R¹ is H, C_1-20 alkyl, C_7-20 alkylaryl, C_7-20 arylalkyl, or C_1-20 perfluoroalkyl;

each Ar¹ and each Ar³ is independently selected from 1,4-phenylene, 1,3-phenylene, naphthyl-1, 4-diyl, naphthyl-1, 5-diyl, 4,4'-biphenylene, diphenyl ether-4,4'-diyl, diphenylthioether-4,4'-diyl,

diphenylisopropylidene-4,4'-diyl,

diphenylhexafluoroisopropylidene-4,4'-diyl,

diphenylalkylene-4,4'-diyl wherein alkylene is

-(CH₂)_q-, q being 1, 3, 5, 7 or 9, p-terphenyl-4,4'-diyl, and bivalent radicals of binaphthalene, anthracene, and phenylnaphthalene; and each Ar² and each Ar⁴ is independently selected from diphenylsulfoxide-4,4'-diyl, diphenylsulfone-4,4'-diyl, diphenyl ketone-4,4'-diyl, and bivalent radicals of diphenyl-C_1-12 alkyl phosphine oxide and diphenyl-C_6-20 aryl phosphine oxide.

2. A block copolymer of claim 1, wherein each Q moiety is OAr¹.

3. A block copolymer of claim 2 , wherein each A moiety and each E moiety is CH₂.

4. A block copolymer of claim 3, wherein Y is hydroxy.

5. A block copolymer of claim 3, wherein Y is -(OAr³O)-Z²-(CH₂CH₂O)_p-R¹ or -(OAr⁴O)-(CH₂CH₂O)_p-R¹.

6. A block copolymer of claim 3, wherein Z¹ is -N(R²)-(SO₂)-C₆H₄- and Z² is -C₆H₄-(SO₂)-N(R²)-.

7. A block copolymer of claim 3, wherein Ar² is diphenylsulfone-4,4'-diyl.

8. A block copolymer of claim 3 , wherein Ar¹ is diphenylisopropylidene-4,4'-diyl or diphenylhexafluoroisopropylidene-4,4^,-diyl.

9. A block copolymer of claim 3, wherein R and R¹ are each independently selected from lauryl, myristyl, palmityl, stearyl, cetyl, methyl, phenyl, octylphenyl, nonylphenyl, and perfluoroalkyl.

10. A block copolymer of claim 7 selected from the group consisting of methyl poly(oxyethylene)-b- poly(aryl ether sulfone), methyl poly(oxyethylene)-b-poly(aryl ether sulfone)-b-poly(ethyleneoxy)methyl, phenyl poly(oxyethylene)-b-poly(aryl ether sulfone), phenyl poly(oxyethylene)-b-poly(aryl ether sulfone)-b-poly(ethyleneoxy)phenyl, stearyl poly(oxyethylene)-b-poly(aryl ether sulfone), stearyl poly(oxyethylene)-b-poly(aryl ether sulfone)-b-poly(ethyleneoxy) stearyl, cetyl poly(oxyethylene)-b-poly(aryl ether sulfone), cetyl poly(oxyethylene)-b-poly(aryl ether sulfone)-b-poly(ethyleneoxy) cetyl, lauryl poly(oxyethylene)-b- poly(aryl ether sulfone), lauryl poly(oxyethylene)-b- poly(aryl ether sulfone)-b-poly(ethyleneoxy) lauryl, octylphenyl poly(oxyethylene)-b-poly(aryl ether sulfone), octylphenyl

poly(oxyethylene)-b-poly(aryl ether sulfone)-b-poly(ethyleneoxy)phenyloctyl, nonylphenyl

poly(oxyethylene)-b-poly(aryl ether sulfone)-b-poly(ethyleneoxy)phenylnonyl, perfluoroalkyl

poly(oxyethylene)-b-poly(aryl ether sulfone), and

perfluoroalkyl poly(oxyethylene)-b-poly(aryl ether sulfone)-b-poly(ethyleneoxy) perfluoroalkyl.

11. A block copolymer of claim 3, wherein the weight ratio (OCH₂CH₂):(OAr¹OAr²) + (OAr²OAr¹) is between 5:1 and 1:20.

12. A block copolymer of claim 1, wherein each of R and R¹ is H or C_1-10 alkyl, n is between 40 and 8,000, X is -[OAr²Q]_m, m is between 4 and 250, Y is -OAr⁴O- [BCH₂O]_p-R¹, and p is between 40 and 8,000, provided that one Q moiety is [OCH₂E]_u, u being between 40 and 8,000, and two Q moieties are selected independently from OAr¹.

13. A block copolymer of claim 12, wherein in one Q, 80% - 100% of E moieties is CH₂; and wherein 80% -100% of combined A moieties and B moieties is CH₂.

14. A block copolymer of claim 12, wherein at least two Q moieties are [OCH₂E]_u.

15. A block copolymer of claim 12, wherein each of R and R¹ is independently H or C_1-3 alkyl.

16. A block copolymer of claim 15, wherein each of R and R¹ is independently H or methyl.

17. A block copolymer of claim 12, wherein at least 80% of Ar² and Ar⁴ is diphenylsulfone-4,4'-diyl.

18. A block copolymer of claim 12, wherein at least 80% of Ar¹ and Ar³ is diphenylisopropylidene-4 , 4 ' -diyl .

19. A block copolymer of claim 12 , wherein -[OAr²Q]_m- includes a polyethylene oxide block or an ethylene oxide-propylene oxide block copolymer.

20. A block copolymer of claim 19, wherein -[OAr²Q]_m- includes a moiety having a molecular weight between 2,000 Da and 200,000 Da, said moiety being a polyethylene oxide block, a polypropylene oxide block, a random ethylene oxide-propylene oxide block copolymer, or a polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer.

21. A block copolymer of claim 12, wherein the total weight percent of polyethylene oxide block and polyethylene oxide-polypropylene oxide random copolymer is up to 80 weight percent of the block copolymer.

22. A block copolymer of claim 21, wherein said total weight percent of polyethylene oxide block and polyethylene oxide-polypropylene oxide random copolymer is between 10 and 60 weight percent of the block

copolymer.

23. A block copolymer of claim 1, wherein n is between 40 and 8,000, u is between 40 and 8,000, p is between 40 and 8,000, and m is between 50 and 400.

24. A block copolymer of claim 23, wherein n is between 100 and 5,000, u is between 100 and 5,000, p is between 100 and 5,000, and m is between 125 and 200.

25. A block copolymer of claim 12, wherein R and R¹ are each independently C_1-3 alkyl.

26. A porous polymer article with a covalently-bonded hydrophilic moiety present on its active surface comprising

a hydrophilic-hydrophobic diblock copolymer or a hydrophilic-hydrophobic-hydrophilic triblock copolymer, or a combination thereof; and

a hydrophobic polymer;

wherein a hydrophobic moiety of said diblock or triblock copolymer mixes with said hydrophobic polymer to form a polymer matrix, and a covalently-bonded

hydrophilic moiety of said diblock or triblock copolymer is present on the active surface of said polymer article.

27. A porous polymer article of claim 26, wherein said diblock or triblock copolymer is of the formula: R- (OCH₂CH₂ ) _n-X-Y wherein R is C_1-20 alkyl, C_7-20 alkylaryl, C_7-20 arylalkyl, or C₁_₂₀ perfluoroalkyl;

n is between 20 and 500;

X is -Z¹-(OAr¹OAr²)_m- or -(OAr²OAr¹)_m-; and

Y is hydroxy, -(OAr³O)-Z²-(CH₂CH₂O)_p-R¹, or - (OAr⁴O)-(CH₂CH₂O)_p-R¹;

in which Z¹ is selected from -N(R²)-(SO₂)-C₆H₄- and -N(R²)-(C=O)-C₆H₄-, R² being C_1-12 alkyl or C_6-20 aryl;

Z² is selected from -C₆H₄-(SO₂)-N(R³) - and -C₆H₄-(C=O)-N(R³)-, R³ being C_1-12 alkyl or C_6-20 aryl;

R¹ is C_1-20 alkyl, C_7-20 alkylaryl, C_7-20 arylalkyl, or C_1-20 perfluoroalkyl;

diphenylisopropylidene-4,4'-diyl,

diphenylhexafluoroisopropylidene-4,4'-diyl,

diphenylalkylene-4,4^,-diyl wherein alkylene is

-(CH₂)_q-, q being 1, 3, 5, 7 or 9, p-terphenyl-4,4'-diyl, and bivalent radicals of binaphthalene, anthracene, and phenylnaphthalene;

each Ar² and each Ar⁴ is independently selected from diphenylsulfoxide-4,4'-diyl, diphenylsulfone-4,4'-diyl, diphenyl ketone-4,4'-diyl, and bivalent radicals of diphenyl-C_1-12 alkyl phosphine oxide and diphenyl-C_6-20 aryl phosphine oxide;

m is between 1 and 250; and

p is between 20 and 500.

28. A porous polymer article of claim 27 having up to 80% by weight of said block copolymer.

29. A porous polymer article of claim 27, wherein Z¹ is -N(R²)-(SO₂)-C₆H₄- and Z² is -C₆H₄-(SO₂)-N(R²)-.

30. A porous polymer article of claim 27, wherein Ar² is diphenylsulfone-4, 4 '-diyl.

31. A porous polymer article of claim 30, wherein each of R and R¹ is independently selected from lauryl, myristyl, palmityl, stearyl, cetyl, methyl, phenyl, octylphenyl, nonylphenyl, and perfluoroalkyl.

32. A porous polymer article of claim 30, wherein said block copolymer is selected from the group

consisting of methyl poly(oxyethylene)-b-poly(aryl ether sulfone), methyl poly(oxyethylene)-b-poly(aryl ether sulfone)-b-poly(ethyleneoxy)methyl, phenyl

poly(oxyethylene)-b-poly(aryl ether sulfone), phenyl poly(oxyethylene)-b-poly(aryl ether sulfone)-b-poly(ethyleneoxy)phenyl, stearyl poly(oxyethylene)-b-poly(aryl ether sulfone), stearyl poly(oxyethylene)-b-poly(aryl ether sulfone)-b-poly(ethyleneoxy)stearyl,cetyl poly(oxyethylene) -b-poly(aryl ether sulfone), cetyl poly(oxyethylene)-b-poly(aryl ether sulfone)-b-poly(ethyleneoxy)cetyl, lauryl poly(oxyethylene)-b-poly(aryl ether sulfone), lauryl poly(oxyethylene)-b-poly(aryl ether sulfone)-b-poly(ethyleneoxy) lauryl, octylphenyl poly(oxyethylene)-b-poly(aryl ether sulfone), octylphenyl poly(oxyethylene)-b-poly(aryl ether sulfone)- b-poly(ethyleneoxy)phenyloctyl, nonylphenyl

poly(oxyethylene)-b-poly(aryl ether sulfone), and

perfluoroalkyl poly(oxyethylene)-b-poly(aryl ether sulfone)-b-poly(ethyleneoxy)perfluoroalkyl, or a mixture thereof.

33. A porous polymer article of claim 27, wherein the weight ratio (OCH₂CH₂):(OAr¹OAr²) + (OAr²OAr¹) of said block copolymer is between 5:1 and 1:20.

34. A porous polymer article of claim 26, wherein said hydrophobic polymer is selected from the group consisting of polyacrylonitrile, polyvinyl halide, polyvinylidene halide, polyimide, polyetherimide,

polyamide, a polymer of -(OAr¹OAr²)-, and copolymers thereof.

35. A porous polymer article of claim 34, wherein said hydrophobic polymer is a polymer or copolymer of -(OAr¹OAr²)-, wherein Ar² is diphenylsulfone-4,4'-diyl.

36. A method of making a porous polymer article with enhanced hydrophilicity comprising the steps of:

providing a casting solution which includes

(i) 0.1 - 50 weight percent of a block copolymer having the formula:

R-(OCH₂CH₂)_n-X-Y wherein R is C₁_₂₀ alkyl, C_7-20 alkylaryl, C_7-20 arylalkyl, or C_1-20 perfluoroalkyl;

n is between 20 and 500;

X is -Z¹-(OAr¹OAr²)_m- or -(OAr²OAr¹)_m-; and Y is hydroxy, -(OAr³O)-Z²-(CH₂CH₂O)_p-R¹, or - (OAr⁴O)-(CH₂CH₂O)_p-R¹;

Z² is selected from -C₆H₄-(SO₂)-N(R³)- and -C₆H₄-(C=O)-N(R³)-, R³ being C_1-12 alkyl or C_6-20 aryl;

R¹ is C_1-20 alkyl, C_7-20 alkylaryl, C_7-20 arylalkyl, or C_1-20 perfluoroalkyl; each Ar¹ and each Ar³ is independently selected from 1,4-phenylene, 1,3-phenylene, naphthyl-1,4-diyl, naphthyl-1, 5-diyl, 4,4'-biphenylene, diphenyl ether-4,4'-diyl, diphenylthioether-4,4'-diyl,

diphenylisopropylidene-4,4'-diyl,

diphenylhexafluoroisopropylidene-4,4'-diyl,

diphenylalkylene-4,4'-diyl wherein alkylene is

m is between 1 and 250; and

p is between 20 and 500;

(ii) 0 - 40 weight percent of polysulfone; and (iii) 40 - 95 weight percent of a polar aprotic solvent selected from N-methylpyrrolidinone, 4-butyrolactone, dimethylsulfoxide, and dimethylformamide;

contacting said casting solution with a nonsolvent coagulation bath until a porous polymer article forms; and

thermally annealing said article in the presence of water to enhance the hydrophilicity of said article.

37. A method of claim 36, wherein the thermal annealing step includes heating said article at a

temperature between 95 and 130°C.

38. A method of claim 36, wherein the thermal annealing step includes heating said article at a

temperature between 40 and 90°C.

39. A method of claim 36, wherein the weight percent of said block copolymer in said casting solution is 5 - 35 weight percent.

40. A method of claim 36, wherein the weight percent of said polysulfone is 0.1 - 30 weight percent.

41. A method of claim 36, wherein said casting solution further includes 5 - 30 weight percent of a hydroxyl-containing reagent selected from polyethylene glycol, water, and C_1-8 alkanol.

42. A method of claim 36, wherein said casting solution includes: 10 weight percent block copolymer, 10 weight percent polysulfone, and 80 weight percent polar aprotic solvent; 10 weight percent block copolymer, 15 weight percent polysulfone, 25 weight percent

polyethylene glycol, and 50 weight percent polar aprotic solvent; or 15 weight percent block copolymer, 5 weight percent polysulfone, and 80 weight percent polar aprotic solvent.

43. A method of claim 36, wherein said polar aprotic solvent is N-methyl pyrrolidinone.

44. A block copolymer, comprising

a central block segment selected from polyethylene oxide block and a polyethylene oxide-polypropylene oxide copolymer, said segment being linked between two polyarylsulfone block segments by ether linkages; and

a first endgroup and a second endgroup, each endgroup selected independently from polyethylene oxide C_1-10 alkyl ether and polyethylene glycol mono-C_1-10 alkyl ether and each linked to an arylsulfone moiety connected to one of said polyaryl sulfone block segments.

45. A polymeric article formed by either the direct extrusion or the injection molding of a

composition containing a block copolymer of claim 12.

46. A polymeric article of claim 45, wherein said composition further contains an inorganic additive.

47. A polymeric article of claim 45, wherein said composition further contains a thermoplastic polymer.