Amphiphilic polyampholytes and related membranes.

Abstract

A series of terpolymers comprising hydrophobic repeat units, anionic repeat units, and cationic repeat units; and their use in anti-fouling coatings and highly anti-fouling membrane filters whose selectivity can be controlled by adjusting the composition of the polymer. The invention also provides a method of purifying compositions such as peptides and proteins, or decontaminating or removing organic solutes from water using the membrane filters of the invention.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of priority to U.S. Provisional Patent Application No. 63 / 235,454, filed August 20, 2021. GOVERNMENT SUPPORT

[0002] This invention was made with government support under Grant No. DE-FE0031851 awarded by the United States Department of Energy, and Grant Nos. 1553661 and 1904465 awarded by the National Science Foundation. The Government has certain rights in this invention. [Background technology]

[0003] Fouling, or the deposition of undesirable materials on surfaces, is a serious problem in many applications where the surfaces are in contact with seawater or surface water. The fouling phenomenon occurs most frequently on ship hulls and other surfaces exposed to the marine environment. 1-4 , pipes and other equipment used in deep water oil extraction 5-9 , piping and heat transfer components 10-12 , and water filtration membranes 13-17 Fouling causes significant economic impacts annually due to reduced productivity, increased energy use, and frequent maintenance and downtime of affected equipment. Thus, there is a need for materials and coatings that resist fouling when exposed to a variety of aqueous solutions containing biopolymers, oils, and microorganisms.

[0004] Fouling (or fouling) is a hindrance that particularly affects the reliable use of membranes for various applications, especially those where the feed has a high organic content (e.g., water and wastewater treatment, food and beverage industry, and bioseparation). Significant reduction in membrane permeability and changes in membrane selectivity due to fouling often occur. Fouling management is a significant component of the costs associated with membrane systems, requiring more energy use, downtime, maintenance and regular cleaning with the use of chemicals, as well as more complex processes.

[0005] In addition, membranes with improved selectivity or the ability to separate solutes with better precision will improve the economic feasibility and energy efficiency of membrane processes for many applications. For example, membranes with tunable pore size and charge on the nanometer scale will be useful in bioseparation, treatment of complex wastewater, selective removal of organics (e.g., dyes) and other contaminants from electrolyte solutions for reuse, water softening, pretreatment of seawater for desalination by reverse osmosis (RO), and final treatment of secondary and tertiary wastewater effluents. In all these cases, it is important to combine selectivity with fouling resistance.

[0006] The researchers screened a wide range of surface chemistries to identify anti-fouling functional groups and gain an understanding of the mechanisms of fouling resistance. They noted that surfaces that are resistant to protein adsorption share four molecular-level characteristics: they are hydrophilic, contain hydrogen bond acceptors but no hydrogen bond donors, and are neutrally charged. 18、19 . PEO brush 18、19 , mannitol group 20 , chimeric peptoids 21、22 , zwitterion 18、23、24 , and polyampholytes 25、26 Several promising chemicals share these characteristics.

[0007] Of these, zwitterions have attracted extensive attention, especially in the membrane field, due to their facile synthesis and incorporation into existing membranes (often via post-processing methods such as grafting). 27、28 Zwitterionic performance for protein adsorption 18、23、24、29、30 and cell adhesion 23、24 The biocompatibility and fouling resistance are due to very small perturbation effects at the polymer-water interface. 29,31 .

[0008] Zwitterions have anionic and cationic groups in the same monomer unit, while polyampholytes have anionic and cationic groups in different monomer units. Like zwitterions, polyampholytes can exhibit excellent anti-fouling properties. 25、26 As mentioned earlier, zwitterions have been extensively studied in membrane systems, but this is not the case for polyampholytes. The few examples in which polyampholytes are used in membrane systems involve the surface modification of common ultrafiltration membranes, mostly by graft copolymerization (UV light or redox initiation) of anionic and cationic monomer units to improve fouling resistance. 26、32 .

[0009] Previous studies have demonstrated that random zwitterionic amphiphilic copolymer (r-ZAC) membranes can be formed via the self-assembly of zwitterionic nanodomains that act as a network of efficient nanochannels for water permeation. 33 The main features of r-ZAC membranes include excellent fouling resistance, a size cutoff of approximately 1–1.5 nm, and low salt ion retention. 33、34However, although a variety of zwitterionic monomers can be synthesized, only a handful are commercially available, and some are only available from one supplier. Furthermore, most zwitterionic monomers have poor solubility in many solvents, further adding to the challenges of their synthesis. As a result, the range of r-ZAC chemicals that can be feasibly converted into membranes that are manufactured on a large scale is limited. On the other hand, ionic or ionizable monomers are widely available, inexpensive, and typically easy to solubilize and synthesize.

[0010] Therefore, there is a need to develop anti-fouling polymeric materials that can be synthesized from readily available ionic or ionizable monomers and that can be used in anti-fouling coatings as well as tunable membranes useful for separation applications. Summary of the Invention [Means for solving the problem]

[0011] In some embodiments, the present invention provides (a) multiple hydrophobic repeat units; (b) a plurality of cationic repeat units; and (c) multiple anionic repeat units; wherein the hydrophobic repeat units, the cationic repeat units, and the anionic repeat units are in random or statistical order.

[0012] In another aspect, the invention provides a thin film composite membrane comprising a porous substrate and a selective layer comprising a polymer of the invention, wherein the average effective pore size of the porous substrate is larger than the average effective pore size of the selective layer, and the selective layer is disposed on a surface of the porous substrate.

[0013] In another aspect, the invention provides a material having an anti-fouling coating comprising a solid substrate and a layer comprising a polymer of the invention, the layer disposed on a surface of the solid substrate.

[0014] In a further aspect, the present invention provides a method for purifying a peptide or protein, comprising contacting a thin film composite membrane of the present invention with a mixture comprising one or more peptides or proteins at a first flow rate, whereby a portion of the mixture is retained by the thin film composite membrane.

[0015] The invention also provides a method for removing organic solutes from water comprising contacting a thin film composite membrane of the invention with an aqueous solution containing the organic solute at a first flow rate, whereby the organic solute is retained by the thin film composite membrane.

[0016] The present invention also provides a method for decontaminating water, comprising contacting a thin film composite membrane of the present invention with a mixture comprising water and one or more contaminants at a first flow rate, whereby the one or more contaminants are retained by the thin film composite membrane.

[0017] In another aspect, the invention provides a method of size-selective separation comprising contacting a thin film composite membrane of the invention with a mixture containing one or more particles of different sizes at a first flow rate, whereby one or more particles of a particular size are retained by the thin film composite membrane. [Brief description of the drawings]

[0018] [Figure 1] NMR spectrum of the chemical structure of PTMS showing copolymerization of three monomer units. [Figure 2A] A schematic diagram of casting PTMS onto a PS35-based membrane is shown. [Figure 2B] Shown are SEM images of PTMS coated on top of PS35 (left) and uncoated PS35 (right). The selective layer is visible on the left. [Diagram 3]NMR spectrum of the chemical structure of PTMS-, showing copolymerization of three monomer units. [Figure 4] SEM images of PTMS-coated (left) and uncoated PS35 (right) on top of PS35 are shown, with the selective layer visible on the left. [Diagram 5] NMR spectrum of the chemical structure of PTMS+ showing copolymerization of three monomer units. [Figure 6] SEM images of PTMS+ coated on top of PS35 (left) and uncoated PS35 (right) are shown, with the selective layer visible on the left. [Figure 7] NMR spectrum of the chemical structure of PTMM showing copolymerization of three monomer units. [Figure 8] SEM images of PTMM coated on top of PS35 (left) and uncoated PS35 (right) are shown, with the selective layer visible on the left. [Figure 9] NMR spectrum of the chemical structure of PTMT-, showing copolymerization of three monomer units. [Figure 10] SEM images of PTMT-coated on top of PS35 (left) and uncoated PS35 (right) are shown, with the selective layer visible on the left. [Figure 11] The results of 25-hour oil-in-water fouling tests of PTMS, PTMS- and PTMS+ are shown. The initial flux of these membranes was set at 7.75 L / m2.h. [Figure 12] The results of 25-h oil-in-water fouling tests of PTMM and poly(2,2,2-trifluoroethyl methacrylate)-random-poly(methacrylic acid) (PTM-) containing 41 mol% TFEMA and 59 mol% MAA as a control are shown. The initial flux of these membranes was set at 7.75 L / m2.h. [Figure 13] FIG. 1 shows an NMR spectrum of the chemical structure of PTMS2 showing the copolymerization of three monomer units. [Figure 14]SEM images of PTMS2 coated on top of PS35 (left) and uncoated PS35 (right) are shown. [Figure 15] FIG. 1 shows an NMR spectrum of the chemical structure of PTMS3, indicating copolymerization of three monomer units. [Figure 16] SEM images of PTMS3 coated on top of PS35 (left) and uncoated PS35 (right) are shown. [Figure 17] The results of 25-hour oil-in-water fouling tests of PTMS, PTMS2, and PTMS3 are shown. The initial flux of these membranes was set at 1.2 L / m2.h. NP030 is a commercial membrane with similar size cutoff and permeance. [Figure 18] Shown are the results of a 25-hour protein fouling test of PTMS2 and PTMS3; lysozyme (left) and BSA (right). The initial flux of these membranes was set at 1 L / m2.h. NP030 is a commercially available membrane of similar size cutoff and permeance. [Figure 19] TEM bright-field images of the self-assembled morphology of r-PAC with different - / + charge ratios but similar hydrophobic monomer content, showing a bicontinuous network of ionic nanochannels (dark) surrounded by a hydrophobic phase (light). (Inset) FFT of the image with arrows corresponding to the characteristic period of the ionic domains. Panel (a) shows that PTMS- exhibits a characteristic period of about 3.1 nm, resulting in a dry ion channel size of about 1.55 nm. Panel (b) shows that PTMS- exhibits a characteristic period of about 4.5 nm, resulting in a dry ion channel size of about 2.25 nm. [Figure 20] 1 is a graph showing modulated DSC analysis of PTMS, PTMS- and PTMS+. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] The present invention is based on the discovery of a new family of terpolymers combining hydrophobic repeat units, anionic repeat units, and cationic repeat units; and their use in anti-fouling membrane filters with tunable selectivity. The present invention, combining hydrophobic repeat units, anionic repeat units, and cationic repeat units, represents the first ampholyte used to form selective membranes. The terpolymers of the present invention, referred to herein as amphiphilic polyampholytes, contain at least 1% each of hydrophobic monomers, anionic monomers, and cationic monomers, which are copolymerized by well-known polymerization reactions (e.g., free radical polymerization). The resulting polymers are insoluble in water.

[0020] These polymers can then be used to form coatings by common methods (e.g., doctor blading, bar coating, spray coating). These coatings can retard or prevent fouling. Anti-fouling is expected to be most effective when the anionic and cationic groups are as close to a 1:1 molar ratio as possible, or when the surface is of near overall neutral charge. Fouling is a major problem in many applications involving aqueous solutions in contact with surfaces, including membrane filtration, preventing fouling of ship hulls and bridges, preventing clogging of pipes, biomaterials, etc.

[0021] When the coating is applied to membranes with large pores, the resulting membranes show not only high fouling resistance but also selectivity resulting from the self-organization of this polymer through interactions between different repeat units (e.g., Coulombic interactions between anionic and cationic groups). When the polymer contains anionic and cationic groups in a ratio close to 1:1, the membranes show near size-based selectivity with effective pore sizes in the range of <3 nm, along with excellent fouling resistance rarely seen in other systems. When one monomer is present in excess, resulting in a net charge on the membrane layer, the membranes also have selectivity resulting from electrostatic interactions / Donnan exclusion while maintaining good size-based selectivity. These membranes may be capable of showing high rejection of various salts, as well as charge-based selectivity (i.e., separating monovalent and divalent ions and separating dyes with different charges). These properties promise applications in water and wastewater treatment, water purification, and bioseparation, as well as other aqueous separations.

[0022] The synthesis and coating process of these films is highly scalable, a fact that demonstrates their usefulness along with several related applications listed.

[0023] polymer In a particular embodiment, the present invention provides a method for producing a method for the treatment of a cancer (a) multiple hydrophobic repeat units; (b) a plurality of cationic repeat units; and (c) multiple anionic repeat units; wherein the hydrophobic repeat units, the cationic repeat units, and the anionic repeat units are in a random or statistical order.

[0024] In certain embodiments, the polymer is insoluble in water.

[0025] In certain embodiments, the molar ratio of cationic repeat units to anionic repeat units is about 1.1:1 to about 1:1.1, or about 1.05:1 to about 1:1.05, or about 1.01:1 to about 1:1.01. In certain preferred embodiments, the molar ratio of cationic repeat units to anionic repeat units is about 1:1. In certain embodiments, a ratio of cationic repeat units to anionic repeat units of about 1:1 provides high fouling resistance.

[0026] In certain embodiments, the net charge of the polymer is between -10 and +10. In further embodiments, the net charge of the polymer is between -9 and +9, -8 and +8, -7 and +7, -6 and +6, -5 and +5, -4 and +4, -3 and +3, -2 and +2, -1 and +1, or 0 (i.e., the polymer is neutral).

[0027] In certain embodiments, the molar ratio of cationic repeat units to anionic repeat units is greater than about 1:1, greater than about 1.25:1, greater than about 1.5:1, greater than about 1.75:1, or greater than about 2:1. In certain such embodiments, the net charge of the polymer is positive. In certain such embodiments, the net charge of the polymer is greater than +10.

[0028] In certain embodiments, the molar ratio of cationic repeat units to anionic repeat units is less than about 1:1, less than about 0.8:1, less than about 0.67:1, less than about 0.57:1, or less than about 0.5:1. In certain such embodiments, the net charge of the polymer is negative. In certain such embodiments, the net charge of the polymer is less than -10.

[0029] In certain embodiments, the molecular weight of the polymer is greater than about 20,000 g / mol, greater than about 40,000 g / mol, greater than about 60,000 g / mol, greater than about 80,000 g / mol, greater than about 100,000 g / mol, or greater than about 120,000 g / mol. In preferred embodiments, the molecular weight of the polymer is greater than about 100,000 g / mol.

[0030] The hydrophobic repeat units limit the swelling of the polymer in water and impart stability to the polymer in an aqueous environment and may be derived from monomers whose homopolymers are insoluble in water and have a glass transition temperature above the temperature of use (e.g., room temperature).

[0031] For use in the applications described herein (eg, anti-fouling coatings and membrane selective layers), the polymers of the invention contain a sufficient amount of hydrophobic repeat units to be insoluble in water under the conditions of use.

[0032] In certain embodiments, the hydrophilic repeat units comprise at least about 30%, at least about 35%, at least about 40%, at least about 45%, at least about 50%, at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, or at least about 90% by weight of the polymer. In preferred embodiments, the hydrophilic repeat units comprise at least about 30% or at least about 45% of the polymer to result in a polymer that is insoluble in water.

[0033] In certain embodiments, the hydrophilic repeat units comprise about 30% to about 99% by weight, about 30% to about 90% by weight, about 40% to about 90% by weight, about 40% to about 80% by weight, about 40% to about 75% by weight, about 40% to about 70% by weight, about 45% to about 75% by weight, about 45% to about 70% by weight, about 50% to about 80% by weight, about 50% to about 75% by weight, or about 50% to about 70% by weight of the polymer.

[0034] In certain embodiments, the hydrophilic repeat units comprise from about 40% to about 90% by weight of the polymer. Certain such polymers may be used in anti-fouling coatings.

[0035] In certain embodiments, the hydrophilic repeat units comprise from about 40% to about 75% by weight of the polymer, preferably from about 50% to about 70% by weight. Certain such polymers may be used in selective membrane layers.

[0036] In certain preferred embodiments of polymers useful in anti-fouling coatings, these amphiphilic polyampholytes comprise about 30-99 wt % (preferably 40-90 wt %) hydrophobic monomers and 0.5-40 wt % (preferably 2.5-25 wt %) each of anionic and cationic monomers, with the molar ratio of anionic to cationic units being as close to 1:1 as possible.

[0037] In certain embodiments, the plurality of cationic repeat units and the plurality of anionic repeat units each constitute at least about 0.5%, at least about 1%, at least about 2.5%, at least about 5%, at least about 10%, at least about 15%, at least about 20%, at least about 25%, at least about 30%, at least about 35%, or at least about 40% by weight of the polymer.

[0038] In certain embodiments, the plurality of cationic repeat units and the plurality of anionic repeat units each constitute from about 0.5% to about 30%, about 0.5% to about 25%, about 1% to about 30%, about 1% to about 25%, about 2% to about 30%, about 2% to about 25%, about 2.5% to about 30%, about 2.5% to about 25%, about 5% to about 30%, or about 5% to about 25% by weight of the polymer.

[0039] In certain embodiments, the plurality of hydrophobic repeat units comprises a mixture of different hydrophobic monomers.

[0040] For example, in some embodiments, each hydrophobic repeat unit is independently selected from the group consisting of 2,2-trifluoroethyl methacrylate (TFEMA), fluorinated acrylates, methacrylates, pentafluoropropyl methacrylate, heptafluorobutyl methacrylate, pentafluorophenyl methacrylate, styrene, methyl methacrylate, and acrylonitrile.

[0041] In further embodiments, each hydrophobic repeat unit is the same and is selected from the group consisting of 2,2-trifluoroethyl methacrylate (TFEMA), fluorinated acrylates, methacrylates, pentafluoropropyl methacrylate, heptafluorobutyl methacrylate, pentafluorophenyl methacrylate, styrene, methyl methacrylate, and acrylonitrile. In certain preferred embodiments, the hydrophobic repeat unit is 2,2-trifluoroethyl methacrylate (TFEMA).

[0042] In some embodiments, the anionic repeat unit carries a negative charge under the conditions of use, i.e., in some embodiments, the anionic repeat unit carries a negative charge in aqueous solution at about pH 4.0, about pH 4.5, about pH 5.0, about pH 5.5, about pH 6.0, about pH 6.5, about pH 7.0, about pH 7.5, about pH 8.0, about pH 8.5, about pH 9.0, about pH 9.5, about pH 10.0, about pH 10.5, about pH 11.0, or about pH 11.5, or higher.

[0043] The anionic repeat units may be selected from methacrylate, acrylate, methacrylamide, acrylamide, styrene or vinyl derivatives that contain carboxylic acid, sulfonate, phosphate, or other ionizable or charged groups that assume a negative charge under the conditions of use.

[0044] In certain embodiments, the multiple anionic repeat units comprise a mixture of different anionic monomers.

[0045] For example, in some embodiments, each anionic repeat unit may be selected from the group consisting of methacrylic acid (MAA), 2-sulfoethyl methacrylate (or 2-sulfoethyl methacrylate) (SEMA), L-tryptophan-methacrylamide (L-Try-MA), D-tryptophan-methacrylamide, L or D-tryptophan-acrylamide, L or D-alanine-methacrylamide, L or D-alanine-acrylamide, L or D-valine-methacrylamide, L or D-valine- ... -isoleucine-methacrylamide, L or D-isoleucine-acrylamide, L or D-allo-isoleucine-methacrylamide, L or D-allo-isoleucine-acrylamide, L or D-methionine-methacrylamide, L or D-methionine-acrylamide, L or D-phenylalanine-methacrylamide, L or D-phenylalanine-acrylamide, L or D-tyrosine-methacrylamide, L or D-tyrosine-acrylamide, L or D-histidine-methacrylamide , L or D-histidine-acrylamide, L or D-glutamic acid-methacrylamide, L or D-glutamic acid-methacrylamide, L or D-aspartic acid-acrylamide, L or D-aspartic acid-methacrylamide, acrylic acid, 2-carboxyethyl acrylate, mono-2-(methacryloyloxy)ethyl succinate, mono-2-(methacryloyloxy)ethyl maleate, sodium 4-vinylbenzenesulfonate, 2-acrylamido-2-methylpropanesulfonic acid, 2-acrylic amido-2-methyl-1-propanesulfonic acid sodium salt, 2-acrylamido-2-methyl-1-propanesulfonic acid, acrylic acid 3-sulfopropyl potassium salt, methacrylic acid 3-sulfopropyl potassium salt, 3-vinylbenzoic acid, 4-vinylbenzoic acid, 2-vinylbenzoic acid, 4-(2-propenyl)benzoic acid, 2-methyl-2-propene-1-sulfonic acid sodium salt, vinylsulfonic acid sodium salt, vinylphosphonic acid, and (4-ethenylphenyl)methylphosphonic acid.

[0046] In further embodiments, each anionic repeat unit is the same and is selected from the group consisting of methacrylic acid (MAA), 2-sulfoethyl methacrylate (SEMA), L-tryptophan-methacrylamide (L-Try-MA), D-tryptophan-methacrylamide, L or D-tryptophan-acrylamide, L or D-alanine-methacrylamide, L or D-alanine-acrylamide, L or D-valine-methacrylamide, L or D-valine-acrylamide, L or D-isoleucine-meth ... amide, L or D-isoleucine-acrylamide, L or D-allo-isoleucine-methacrylamide, L or D-allo-isoleucine-acrylamide, L or D-methionine-methacrylamide, L or D-methionine-acrylamide, L or D-phenylalanine-methacrylamide, L or D-phenylalanine-acrylamide, L or D-tyrosine-methacrylamide, L or D-tyrosine-acrylamide, L or D-histidine-methacrylamide, L or D- Histidine-acrylamide, L or D-glutamic acid-methacrylamide, L or D-glutamic acid-methacrylamide, L or D-aspartic acid-acrylamide, L or D-aspartic acid-methacrylamide, acrylic acid, 2-carboxyethyl acrylate, mono-2-(methacryloyloxy)ethyl succinate, mono-2-(methacryloyloxy)ethyl maleate, sodium 4-vinylbenzenesulfonate, 2-acrylamido-2-methylpropanesulfonic acid, 2-acryla and m is selected from the group consisting of amido-2-methyl-1-propanesulfonic acid sodium salt, 2-acrylamido-2-methyl-1-propanesulfonic acid, acrylic acid 3-sulfopropyl potassium salt, methacrylic acid 3-sulfopropyl potassium salt, 3-vinylbenzoic acid, 4-vinylbenzoic acid, 2-vinylbenzoic acid, 4-(2-propenyl)benzoic acid, 2-methyl-2-propene-1-sulfonic acid sodium salt, vinylsulfonic acid sodium salt, vinylphosphonic acid, and (4-ethenylphenyl)methylphosphonic acid.

[0047] In certain such embodiments, the anionic repeat unit is selected from the group consisting of methacrylic acid (MAA), 2-sulfoethyl methacrylate (SEMA), and L-tryptophan-methacrylamide (L-Try-MA). In a preferred embodiment, the anionic repeat unit is methacrylic acid (MAA). In another preferred embodiment, the anionic repeat unit is 2-sulfoethyl methacrylate (SEMA).

[0048] In some embodiments, the cationic repeat unit is positively charged under the conditions of use, i.e., in some embodiments, the cationic repeat unit is positively charged in aqueous solution at or below about pH 1.0, about pH 1.5, about pH 2.0, about pH 2.5, about pH 3.0, about pH 3.5, about pH 4.0, about pH 4.5, about pH 5.0, about pH 5.5, about pH 6.0, about pH 6.5, about pH 7.0, about pH 7.5, about pH 8.0, about pH 8.5, about pH 9.0, or about pH 9.5.

[0049] The cationic repeat units may be selected from methacrylate, acrylate, methacrylamide, acrylamide, styrene or vinyl derivatives containing amine, ammonium, pyridinium, imidazolium, phosphonium, pyrrolidinium or other ionizable or charged groups that assume a positive charge under the conditions of use. In a preferred embodiment, the cationic repeat units carry a strong cationic charge, such as a quaternary ammonium group.

[0050] In certain embodiments, the multiple cationic repeat units comprise a mixture of different cationic monomers.

[0051] For example, in some embodiments, each cationic repeat unit is independently selected from the group consisting of [2-(methacryloyloxy)ethyl]trimethylammonium chloride (MAETA), [3-(methacryloylamino)propyl]trimethylammonium chloride, [2-(acryloyloxy)ethyl]trimethylammonium chloride, (3-acrylamidopropyl)trimethylammonium chloride, 4-vinylbenzyl(triphenyl)phosphonium chloride, (vinylbenzyl)trimethylammonium chloride methacrylate, 3-vinylaniline, 4-vinylaniline, 2-isopropenylaniline, N-(3-aminopropyl)methacrylamide hydrochloride, N-vinylimidazolium salts, 1-allyl-3-vinylimidazolium salts, l-allyl-2-methyl-5-vinyl-pyridinium salts, l-allyl-5-vinyl-pyridinium salts, and 1-methyl-l-(l-vinylcyclohexyl)pyrrolidinium iodide.

[0052] In a further embodiment, each cationic repeat unit is the same and is selected from the group consisting of [2-(methacryloyloxy)ethyl]trimethylammonium chloride (MAETA), [3-(methacryloylamino)propyl]trimethylammonium chloride, [2-(acryloyloxy)ethyl]trimethylammonium chloride, (3-acrylamidopropyl)trimethylammonium chloride, 4-vinylbenzyl(triphenyl)phosphonium chloride, (vinylbenzyl)trimethylammonium chloride methacrylate, 3-vinylaniline, 4-vinylaniline, 2-isopropenylaniline, N-(3-aminopropyl)methacrylamide hydrochloride, N-vinylimidazolium salts, 1-allyl-3-vinylimidazolium salts, l-allyl-2-methyl-5-vinyl-pyridinium salts, l-allyl-5-vinyl-pyridinium salts, and 1-methyl-l-(l-vinylcyclohexyl)pyrrolidinium iodide.

[0053] In certain embodiments, the cationic repeat unit is [2-(methacryloyloxy)ethyl]trimethylammonium chloride (MAETA).

[0054] In certain preferred embodiments, the cationic repeat units comprise a quaternary ammonium group.

[0055] In an embodiment, the polymer is (a) multiple hydrophobic repeat units; (b) a plurality of cationic repeat units; and (c) multiple anionic repeat units; consisting essentially of and consisting of The hydrophobic repeat units, the cationic repeat units, and the anionic repeat units are in a random or statistical order.

[0056] The polymers of the present invention can be made according to the examples provided herein. The polymers can be synthesized from vinyl monomers (e.g., acrylates, methacrylates, acrylamides, styrene derivatives, acrylonitrile) using well-known polymerization methods (e.g., free radical polymerization).

[0057] The polymers described herein have not been previously prepared or studied. Although combinations of anionic and cationic monomers have been used as anti-fouling coatings, the incorporation of hydrophobic groups into such known materials was predicted to reduce fouling resistance; nevertheless, the resulting materials exhibit fouling resistance comparable to or even exceeding that of all-hydrophilic coatings.

[0058] Self-assembly of polyampholytes, let alone amphiphilic polyampholytes with additional functional groups, is not well studied at all. The interactions between the repeat units of amphiphilic polyampholytes are unlikely to be the same as those observed in zwitterionic amphiphilic copolymers (ZACs).

[0059] Additionally, the present invention is advantageous because ionic or ionizable monomers are more widely available, less expensive, and typically easier to solubilize compared to zwitterionic monomers. Furthermore, the wide selection of monomers allows for a variety of combinations of anionic and cationic units with potentially different membrane performance, including amino acid-based monomers for chiral and other bioseparations.

[0060] The term "polyampholyte" as used herein is a polymer that contains both anionically and cationically charged repeat units. They are typically very hydrophilic and often water-soluble in the absence of non-ionic groups. Thus, the polymers described in this invention are referred to as "amphiphilic polyampholytes" due to the presence of both hydrophobic and amphoteric segments on the same backbone.

[0061] As used herein, the term "charged" is used to describe a species that carries an overall deficiency or excess of electrons relative to the total valence electron count of the species.

[0062] The term "anionic" as used herein refers to a species that has an overall excess of electrons relative to the total valence electron count of the species.

[0063] As used herein, the term "cationic" refers to a species that has an overall deficiency of electrons relative to the species' total valence electron count.

[0064] As used herein, the term "net charge" refers to the overall total charge on a polymer, including cationic and anionic moieties. The net charge is calculated as follows: (number of positive charges) - (number of negative charges).

[0065] The term "statistical order" refers to a polymer in which the arrangement of the constituent repeat units follows a statistical rule. The statistical order is determined by the reaction kinetics of chemically distinct monomer reactants (or repeat unit reactants). In some embodiments, the statistical order encompasses random ordering.

[0066] A polymer with "random order" (alternatively called a "random copolymer") is a polymer in which the probability of finding a given type of repeat unit at a particular point in the chain is equal to the mole fraction of that repeat unit in the polymer.

[0067] film The novel polymeric materials of the present invention form highly fouling resistant surfaces with controlled surface charge. The polymeric materials are therefore useful for the preparation of membranes useful for anti-fouling applications. Membranes can be prepared by coating these polymeric materials onto porous supports that provide controlled selectivity corresponding to effective pore sizes of <4 nm, preferably between 0.5-2 nm, combined with fouling resistance, as well as tunable charge-based selectivity through the incorporation of excess charge into the polymer. The present invention has applications in nanofiltration, ultrafiltration, and reverse osmosis applications.

[0068] Anti-fouling coatings can be applied to a variety of surfaces (e.g., pipes, ship hulls, exterior of surfaces that will be immersed in water, biomedical materials) using well-known methods (e.g., spray coating, roll coating, painting). They are expected to prevent the adsorption of bio-organic macromolecules (e.g., proteins, alginates, natural organic matter) as well as oils onto underwater surfaces.

[0069] Another application of these amphiphilic polyampholytes is as a selective layer in selective anti-fouling membranes. To be used as a membrane selective layer, the polymer needs to be insoluble in water but permeable to water. Thus, preferred compositions contain a low content of hydrophobic repeat units (e.g., 40-75% by weight; preferably 50-70% by weight), with the remainder being a combination of anionic and cationic repeat units. The ratio of these charged groups affects the selectivity of the solute.

[0070] In some embodiments, the invention provides a thin film composite membrane comprising a porous substrate and a selective layer comprising a polymer of the invention, wherein the average effective pore size of the porous substrate is larger than the average effective pore size of the selective layer, and the selective layer is disposed on a surface of the porous substrate.

[0071] In some embodiments, the selective layer has a thickness of from about 10 nm to about 10 μm, or from about 10 nm to about 3 μm, or from about 10 nm to about 1 μm.

[0072] In some embodiments, the selective layer has an average effective pore size of less than about 4 nm, hi further embodiments, the selective layer has an average effective pore size of about 0.1 nm to about 2.0 nm, about 0.5 nm to about 2.0 nm, about 0.1 nm to about 1.2 nm, about 0.5 nm to about 1.2 nm, or about 0.7 nm to about 1.2 nm.

[0073] In some embodiments, the net charge of the polymer is positive and the thin film composite membrane rejects positively charged solutes and salts, or in some embodiments, the net charge of the polymer is negative and the thin film composite membrane rejects negatively charged solutes and salts.

[0074] In some embodiments, the net charge of the polymer is between -10 and +10; the selective layer exhibits size-based selectivity among uncharged organic molecules. In certain such embodiments, the net charge of the polymer is between -9 and +9, -8 and +8, -7 and +7, -6 and +6, -5 and +5, -4 and +4, -3 and +3, -2 and +2, -1 and +1, or 0 (i.e., the polymer is neutral).

[0075] In certain embodiments, the selective layer exhibits a rejection rate of about 95% or greater, or about 99% or greater, for neutral molecules having a hydrated diameter of about 1.5 nm or greater.

[0076] In certain embodiments, the selective layer exhibits anti-fouling properties.

[0077] In certain embodiments, the selective layer exhibits resistance to fouling by oil emulsions.

[0078] In certain embodiments, the selective layer exhibits resistance to fouling due to adsorption of bioorganic macromolecules (eg, proteins, alginates, organic matter).

[0079] The membrane is prepared by coating methods well established in the art. For example, the polymer is dissolved in a suitable solvent. This solution is coated onto a porous support (e.g., a membrane with large pores in the microfiltration or ultrafiltration range) using established methods (e.g., doctor blading, bar coating, spray coating). The solvent is evaporated. In certain preferred embodiments, the coated membrane is immersed in water or another non-solvent to accelerate precipitation. The product is a thin film composite (TFC) membrane that includes at least two layers: a porous support with large pores that provides mechanical integrity, and a thin layer of polymer (preferably <10 μm, more preferably <3 μm, even more preferably <1 μm) that serves as the "selective layer" of the membrane.

[0080] The resulting membranes exhibit near-size-based separation of neutral organic molecules. When the molar ratio of anionic and cationic groups is about 1:1, the membranes are near-size selective. These membranes are also more resistant to fouling.

[0081] Different molar charge ratios result in the rejection of solutes based on their charge, resulting in a higher rejection of charged solutes than neutral solutes of the same size, as well as increased salt rejection. Charge ratios can also affect effective pore size, presumably by changing how the polymers self-assemble through Coulombic interactions during membrane formation. The data below show that polymers with an excess of one charge have larger effective pore sizes.

[0082] All amphiphilic polyampholyte TFC membranes tested so far show excellent anti-fouling properties comparable to the best in the field, including those made from zwitterionic amphiphilic copolymers (ZACs). 34-39 All membranes tested (see Examples below) showed no measurable irreversible fouling.

[0083] The pore size and net charge of these membranes can be tuned by utilizing different monomers, different monomer ratios, and monomers with crosslinkable groups (e.g., 1-allyl-3-vinylimidazolium salts; l-allyl-2-methyl-5-vinyl-pyridinium salts; l-allyl-5-vinyl-pyridinium salts).

[0084] In a further embodiment, the present invention provides a material having an anti-fouling coating comprising a solid substrate and a layer comprising a polymer of the present invention, the layer being disposed on a surface of the solid substrate.

[0085] In certain embodiments, the layer has a thickness of from about 10 nm to about 10 μm, or from about 10 nm to about 3 μm, or from about 10 nm to about 1 μm.

[0086] How to use The membranes described herein are useful in a variety of applications, particularly in aqueous separation applications, including water and wastewater treatment, bioseparation, water reuse, and pharmaceutical purification and concentration. Wastewater treatment applications include water softening applications, as well as the treatment of complex, highly polluted water streams, water streams containing several solvents and / or at high temperatures that would damage uncrosslinked membrane materials, and frac water or produced water from oil and gas extraction that is high in salinity and high in temperature.

[0087] In some embodiments, the membranes described herein may be used in water and wastewater treatment applications. In certain such embodiments, a contaminated solution is filtered through a thin film composite (TFC) membrane, whereby one or more contaminants are retained by the TFC membrane and removed from the solution. In certain such embodiments, the fouling resistance of the membrane allows the solution to maintain a steady flux through the membrane. The undesired contaminants may be, for example, organic solutes. In further embodiments, the undesired contaminants may be fragmented antibodies, aggregated antibodies, host cell proteins, polynucleotides, endotoxins, or viruses.

[0088] In a related use, the membranes described herein can be used in water reuse applications, where a contaminated water stream is filtered through the TFC membrane, whereby one or more contaminants are retained by the TFC membrane, and the filtrate is reused, optionally within the same facility, and optionally after further treatment.

[0089] Thus, in certain embodiments, the present invention provides a method for removing organic solutes from water comprising contacting a thin film composite membrane as described herein with an aqueous solution containing the organic solute at a first flow rate, whereby the organic solute is retained by the thin film composite membrane.

[0090] In some embodiments, substantially all of the organic solute is retained by the thin film composite membrane.

[0091] In a further embodiment, the present invention provides a method of decontaminating water, comprising contacting a thin film composite membrane as described herein with a mixture comprising water and one or more contaminants at a first flow rate, whereby the one or more contaminants are retained by the thin film composite membrane.

[0092] In some embodiments, substantially all of the contaminants are retained by the thin film composite membrane.

[0093] In certain embodiments, the flow path of the aqueous solution or mixture containing water is substantially through the macropores of the thin film composite membrane.

[0094] In certain embodiments, the present invention provides washing the thin film composite membrane; and Repeating the above steps. The method according to any one of the preceding claims, further comprising:

[0095] In further embodiments, the membranes described herein may be used in bioseparation applications. In such embodiments, the thin film composite membranes preferably have pore sizes small enough to retain peptide drugs and other low molar mass biopharmaceuticals while allowing the removal of small molecule solutes and / or salts.

[0096] Thus, in certain embodiments, the present invention provides a method for purifying a peptide or protein, comprising contacting a thin film composite membrane of the present invention with a mixture comprising one or more peptides or proteins at a first flow rate, whereby a portion of the mixture is retained by the thin film composite membrane.

[0097] In some embodiments, the part of the mixture that is retained by the TFC membrane comprises one or more peptides or proteins.In certain such embodiments, one or more contaminants present in the initial mixture that comprises one or more peptides or proteins are not retained by the TFC membrane, but rather flow through the membrane.Thus, this process separates the desired peptides or proteins from the undesired contaminants.

[0098] In certain embodiments, substantially all of the one or more peptides or proteins are retained by the thin film composite membrane.

[0099] The method may further comprise the step of releasing the retained peptide or protein from the TFC membrane. In such embodiments, the method further comprises contacting the protein or peptide retained by the TFC membrane with a second fluid at a second flow rate, thereby releasing a portion of the retained peptide or protein from the TFC membrane.

[0100] The second fluid may be a buffer. The second fluid may comprise a salt.

[0101] The membranes described herein are also useful for size-selective separation applications. The pore size and net charge of the membrane can be tailored depending on the desired application of the TFC membrane, for example, by selecting different monomers, different monomer ratios, or by crosslinking different functional groups onto the constituent monomers.

[0102] Thus, in some embodiments, the present invention provides a method of size-selective separation comprising contacting a thin film composite membrane as described herein with a mixture containing one or more particles of different sizes at a first flow rate, whereby one or more particles of a particular size are retained by the thin film composite membrane. EXAMPLES

[0103] The present disclosure will be further described with reference to the following specific examples, which are offered by way of illustration and are not intended to limit the scope of the disclosure or the claims.

[0104] Example 1. Synthesis of poly(2,2,2-trifluoroethyl methacrylate)-random-poly(2-(methacryloyloxy)ethyl]trimethylammonium chloride)-random-poly(2-sulfoethyl methacrylate) (PTMS) In this example, a random terpolymer was prepared using three monomer units: 2-sulfoethyl methacrylate (SEMA, Polysciences), [2-(methacryloyloxy)ethyl]trimethylammonium chloride (MAETA, Sigma-Aldrich), and 2,2,2-trifluoroethyl methacrylate (TFEMA, ACROS Organics). The first two monomers were passed through a column of neutral activated alumina (Sigma-Aldrich) to remove inhibitors, and the last monomer was passed through a column of basic activated alumina (Sigma-Aldrich). SEMA (2.42 g, 12.4 mmol), MAETA (2.58 g, 12.4 mmol), and 2,2,2-trifluoroethyl methacrylate (5.00 g, 29.7 mmol) were dissolved in this order in dimethyl sulfoxide (DMSO, 40 mL). Azobisisobutyronitrile (AIBN, 0.01 g, Aldrich) was added to the flask. The flask was sealed with a rubber septum. Nitrogen was bubbled through the reaction mixture for 30 minutes to purge dissolved oxygen. The flask was then kept at 60°C with stirring at 300 rpm for 17 hours. After the reaction, 1 g of 4-methoxyphenol (MEHQ) was added to stop the synthesis. The reaction mixture, which was observed to be viscous, was then precipitated in acetone and purified by stirring two fresh portions of 1:5 by volume ratio of methanol to acetone for at least 5 hours and two fresh portions of acetone for at least 5 hours. Finally, the terpolymer was dried in a vacuum oven at 60°C for 72 hours. The composition of the terpolymer was determined using the ratio of protons from the three different monomer units, 1 The composition was calculated from the H-NMR spectrum (Figure 1). The calculated composition was 22 mol% SEMA, 22 mol% MAETA, and 56 mol% TFEMA. The final conversion of this reaction was 45%.

[0105] Example 2. Formation of thin film composite membranes from PTMS In this example, the polymer described in Example 1 was used to fabricate the membrane. A schematic diagram is shown in Figure 2a. The terpolymer (0.5 g) was dissolved in trifluoroethanol (TFE, 9.5 g) at about 25°C. The terpolymer solution was passed through a 0.45 micrometer syringe filter (Whatman) and further degassed in a vacuum oven for at least 1 hour. The membrane was prepared by coating a thin layer of the terpolymer solution onto a commercial ultrafiltration (UF) membrane using a film applicator rod. A PS35 ultrafiltration membrane purchased from Solecta (Oceanside, CA) was used as the base membrane. After coating, the membrane was immersed in a water bath.

[0106] The thickness and morphology of the membranes were determined by examination of the freeze-fractured cross-sections of the membranes using a scanning electron microscope (SEM, Phenom G2 Pure Tabletop SEM). In Figure 2b, SEM images of the uncoated base membrane (right) and the coated membrane (left) are shown at the same magnification. It can be observed that the coating layer is dense (i.e., free of macroscopic pores) with a thickness of about 0.7 micrometers.

[0107] Example 3. Synthesis of poly(2,2,2-trifluoroethyl methacrylate)-random-poly(2-(methacryloyloxy)ethyl]trimethylammonium chloride)-random-poly(2-sulfoethyl methacrylate) (PTMS-) In this example, a random terpolymer was prepared using three monomer units: 2-sulfoethyl methacrylate (SEMA, Polysciences), [2-(methacryloyloxy)ethyl]trimethylammonium chloride (MAETA, Sigma-Aldrich), and 2,2,2-trifluoroethyl methacrylate (TFEMA, ACROS Organics). The first two monomers were passed through a column of neutral activated alumina (Sigma-Aldrich) to remove inhibitors, and the last monomer was passed through a column of basic activated alumina (Sigma-Aldrich). SEMA (3.39 g, 17.5 mmol), MAETA (1.55 g, 7.5 mmol), and 2,2,2-trifluoroethyl methacrylate (4.94 g, 29.4 mmol) were dissolved in this order in dimethyl sulfoxide (DMSO, 40 mL). Azobisisobutyronitrile (AIBN, 0.01 g, Aldrich) was added to the flask. The flask was sealed with a rubber septum. Nitrogen was bubbled through the reaction mixture for 30 minutes to purge dissolved oxygen. The flask was then kept at 60°C with stirring at 300 rpm for 17 hours. After the reaction, 1 g of 4-methoxyphenol (MEHQ) was added to stop the synthesis. The reaction mixture, which was observed to be viscous, was then precipitated in acetone and purified by stirring two fresh portions of 1:3 volume ratio ethanol to hexane for at least 8 hours. Finally, the terpolymer was dried in a vacuum oven at 60°C for 72 hours. The composition of the terpolymer was determined using the ratio of protons from the three different monomer units, 1 The composition was calculated from the H-NMR spectrum (Figure 3). The calculated composition was 28 mol% SEMA, 16 mol% MAETA, and 56 mol% TFEMA. The final conversion of this reaction was 58%.

[0108] Example 4. Formation of thin film composite membranes from PTMS- In this example, the polymer described in Example 3 was used to prepare a membrane. The terpolymer (0.5 g) was dissolved in trifluoroethanol (TFE, 9.5 g) at about 25° C. The terpolymer solution was passed through a 0.45 micrometer syringe filter (Whatman) and further degassed in a vacuum oven for at least 1 hour. The membrane was prepared by coating a thin layer of the terpolymer solution onto a commercially available ultrafiltration (UF) membrane using a film applicator rod. A PS35 ultrafiltration membrane purchased from Solecta (Oceanside, CA) was used as the base membrane. After coating, the membrane was immersed in a water bath.

[0109] The thickness and morphology of the membranes were determined by examination of the cryofractured surfaces of the membranes using a scanning electron microscope (SEM, Phenom G2 Pure Tabletop SEM). In Figure 4, SEM images of the uncoated base membrane (right) and the coated membrane (left) are shown at the same magnification. It can be observed that the coating layer is dense (i.e., free of macroscopic pores) with a thickness of about 0.7 micrometers.

[0110] Example 5. Synthesis of poly(2,2,2-trifluoroethyl methacrylate)-random-poly(2-(methacryloyloxy)ethyl]trimethylammonium chloride)-random-poly(2-sulfoethyl methacrylate) (PTMS+) In this example, a random terpolymer was prepared using three monomer units: 2-sulfoethyl methacrylate (SEMA, Polysciences), [2-(methacryloyloxy)ethyl]trimethylammonium chloride (MAETA, Sigma-Aldrich), and 2,2,2-trifluoroethyl methacrylate (TFEMA, ACROS Organics). The first two monomers were passed through a column of neutral activated alumina (Sigma-Aldrich) to remove inhibitors, and the last monomer was passed through a column of basic activated alumina (Sigma-Aldrich). SEMA (1.45 g, 7.5 mmol), MAETA (3.61 g, 17.4 mmol), and 2,2,2-trifluoroethyl methacrylate (5.06 g, 30.1 mmol) were dissolved in this order in dimethyl sulfoxide (DMSO, 40 ml). Azobisisobutyronitrile (AIBN, 0.01 g, Aldrich) was added to the flask. The flask was sealed with a rubber septum. Nitrogen was bubbled through the reaction mixture for 30 minutes to purge dissolved oxygen. The flask was then kept at 60°C with stirring at 300 rpm for 17 hours. After the reaction, 1 g of 4-methoxyphenol (MEHQ) was added to quench the synthesis. The reaction mixture, which was observed to be viscous, was then precipitated with 1:1 hexane to acetone by volume and purified by stirring two fresh portions of 1:3 ethanol to hexane by volume for at least 8 hours. Finally, the terpolymer was dried in a vacuum oven at 60°C for 72 hours. The composition of the terpolymer was determined using the ratio of protons from the three different monomer units, 1 The composition was calculated from the H-NMR spectrum (FIG. 5). The calculated composition was 15 mol% SEMA, 29 mol% MAETA, and 56 mol% TFEMA. The final conversion of this reaction was 66%.

[0111] Example 6. Formation of thin film composite membrane from PTMS+ In this example, the polymer described in Example 5 was used to prepare a membrane. The terpolymer (0.5 g) was dissolved in trifluoroethanol (TFE, 9.5 g) at about 25° C. The terpolymer solution was passed through a 0.45 micrometer syringe filter (Whatman) and further degassed in a vacuum oven for at least 1 hour. The membrane was prepared by coating a thin layer of the terpolymer solution onto a commercially available ultrafiltration (UF) membrane using a film applicator rod. A PS35 ultrafiltration membrane purchased from Solecta (Oceanside, CA) was used as the base membrane. After coating, the membrane was immersed in a water bath.

[0112] The thickness and morphology of the membranes were determined by examination of the cryofractured surfaces of the membranes using a scanning electron microscope (SEM, Phenom G2 Pure Tabletop SEM). In Figure 6, SEM images of the uncoated base membrane (right) and the coated membrane (left) are shown at the same magnification. It can be observed that the coating layer is dense (i.e., free of macroscopic pores) with a thickness of about 0.6 micrometers.

[0113] Example 7. Synthesis of poly(2,2,2-trifluoroethyl methacrylate)-random-poly(2-(methacryloyloxy)ethyl)trimethylammonium chloride)-random-poly(methacrylic acid) (PTMM) In this example, a random terpolymer was prepared using three monomer units: methacrylic acid (MAA, Sigma-Aldrich), [2-(methacryloyloxy)ethyl]trimethylammonium chloride (MAETA, Sigma-Aldrich), and 2,2,2-trifluoroethyl methacrylate (TFEMA, ACROS Organics). The first two monomers were passed through a column of neutral activated alumina (Sigma-Aldrich) to remove inhibitors, and the last monomer was passed through a column of basic activated alumina (VWR). MAA (1.46 g, 17.0 mmol), MAETA (3.54 g, 17.0 mmol), and 2,2,2-trifluoroethyl methacrylate (5.00 g, 29.7 mmol) were dissolved in this order in dimethyl sulfoxide (DMSO, 40 mL). Azobisisobutyronitrile (AIBN, 0.01 g, Aldrich) was added to the flask. The flask was sealed with a rubber septum. Nitrogen was bubbled through the reaction mixture for 30 minutes to purge dissolved oxygen. The flask was then kept at 60°C with stirring at 300 rpm for 17 hours. After the reaction, 1 g of 4-methoxyphenol (MEHQ) was added to stop the synthesis. The reaction mixture, which was observed to be viscous, was then precipitated in acetone and purified by stirring two fresh portions of 1:3 volume ratio ethanol to hexane for at least 5 hours and two fresh portions of acetone for at least 5 hours. Finally, the terpolymer was dried in a vacuum oven at 60°C for 72 hours. The composition of the terpolymer was determined using the ratio of protons from the three different monomer units, 1 The composition was calculated from the H-NMR spectrum (Figure 7). The calculated composition was 25 mol% MAA, 25 mol% MAETA, and 50 mol% TFEMA. The final conversion of this reaction was 57%.

[0114] Example 8. Formation of thin film composite membranes from PTMM In this example, the polymer described in Example 7 was used to prepare a membrane. The terpolymer (0.5 g) was dissolved in methanol (MeOH, 9.5 g) at about 25° C. The terpolymer solution was passed through a 0.45 micrometer syringe filter (Whatman) and further degassed in a vacuum oven for at least 1 hour. The membrane was prepared by coating a thin layer of the terpolymer solution onto a commercially available ultrafiltration (UF) membrane using a film applicator rod. A PS35 ultrafiltration membrane purchased from Solecta (Oceanside, CA) was used as the base membrane. After coating, the membrane was immersed in a water bath.

[0115] The thickness and morphology of the membranes were determined by examination of the cryofractured surfaces of the membranes using a scanning electron microscope (SEM, Phenom G2 Pure Tabletop SEM). In Figure 8, SEM images of the uncoated base membrane (right) and the coated membrane (left) are shown at the same magnification. It can be observed that the coating layer is dense (i.e., free of macroscopic pores) with a thickness of about 0.4 micrometers.

[0116] Example 9. Synthesis of poly(2,2,2-trifluoroethyl methacrylate)-random-poly(2-(methacryloyloxy)ethyl]trimethylammonium chloride)-random-poly(L-tryptophan-methacrylamide) (PTMT-) In this example, a random terpolymer was prepared using three monomer units: L-tryptophan-methacrylamide (L-Try-MA, synthesized), [2-(methacryloyloxy)ethyl]trimethylammonium chloride (MAETA, Sigma-Aldrich), and 2,2,2-trifluoroethyl methacrylate (TFEMA, ACROS Organics). MAETA was passed through a column of neutral activated alumina (Sigma-Aldrich) to remove the inhibitor, and TFEMA was passed through a column of basic activated alumina (Sigma-Aldrich). L-Try-MA (1.18 g, 4.2 mmol), MAETA (0.37 g, 1.8 mmol), and 2,2,2-trifluoroethyl methacrylate (1.55 g, 9.2 mmol) were dissolved in dimethyl sulfoxide (DMSO, 11.3 mL) in this order. Azobisisobutyronitrile (AIBN, 0.003 g, Aldrich) was added to the flask. The flask was sealed with a rubber septum. Nitrogen was bubbled through the reaction mixture for 30 minutes to purge dissolved oxygen. The flask was then kept at 60° C. with stirring at 300 rpm for 17 hours. After the reaction, 0.3 g of 4-methoxyphenol (MEHQ) was added to stop the synthesis. The reaction mixture, which was observed to be viscous, was then precipitated in acetone and purified by stirring four fresh portions of 1:2 volume ratio ethanol to hexane for at least 5 hours. Finally, the terpolymer was dried in a vacuum oven at 60° C. for 72 hours. The composition of the terpolymer was determined using the ratio of protons from the three different monomer units, 1 The composition was calculated from the H-NMR spectrum (FIG. 9). The calculated composition was 34 mol% L-Try-MA, 15 mol% MAETA, and 51 mol% TFEMA. The final conversion of this reaction was 30%.

[0117] Example 10. Formation of thin film composite membranes from PTMT- In this example, the polymer described in Example 9 was used to prepare a membrane. The terpolymer (0.2 g) was dissolved in DMSO (3.8 g) at about 25° C. The terpolymer solution was passed through a 0.45 micrometer syringe filter (Whatman) and further degassed in a vacuum oven for at least 1 hour. The membrane was prepared by coating a thin layer of the terpolymer solution onto a commercially available ultrafiltration (UF) membrane using a film applicator rod. A PS35 ultrafiltration membrane purchased from Solecta (Oceanside, CA) was used as the base membrane. After coating, the membrane was immersed in a water bath.

[0118] The thickness and morphology of the membranes were determined by examination of the cryofractured surfaces of the membranes using a scanning electron microscope (SEM, Phenom G2 Pure Tabletop SEM). In Figure 10, SEM images of the uncoated base membrane (right) and the coated membrane (left) are shown at the same magnification. It can be observed that the coating layer is dense (i.e., free of macroscopic pores) with a thickness of about 0.6 micrometers.

[0119] Example 11. Fouling resistance of polyampholyte terpolymer membranes In this example, membranes prepared as described in Examples 2, 4, 6, and 8 were used in experiments to determine their fouling resistance. Retention experiments were performed with a cell volume of 10 mL and 4.1 cm 2 The experiments were carried out in an Amicon 8010 stirred dead-end filtration cell (Millipore) with an effective filtration area of ​​1000 nm. The cell was stirred at 500 rpm. The feed solution consisted of a 1500 ppm oil-in-water emulsion (9:1 ratio of soybean oil:DC193 surfactant (obtained from Dow-Corning)) and was prepared by blending the oil, water, and surfactant in a blender at high rpm for approximately 3 minutes.

[0120] Example 12. Synthesis of poly(2,2,2-trifluoroethyl methacrylate)-random-poly(2-(methacryloyloxy)ethyl]trimethylammonium chloride)-random-poly(2-sulfoethyl methacrylate) (PTMS2) In this example, a random terpolymer was prepared using three monomer units: 2-sulfoethyl methacrylate (SEMA, Polysciences), [2-(methacryloyloxy)ethyl]trimethylammonium chloride (MAETA, Sigma-Aldrich), and 2,2,2-trifluoroethyl methacrylate (TFEMA, ACROS Organics). The first two monomers were passed through a column of neutral activated alumina (Sigma-Aldrich) to remove inhibitors, and the last monomer was passed through a column of basic activated alumina (Sigma-Aldrich). SEMA (1.93 g, 9.9 mmol), MAETA (2.07 g, 9.9 mmol), and 2,2,2-trifluoroethyl methacrylate (6.00 g, 35.7 mmol) were dissolved in this order in dimethyl sulfoxide (DMSO, 40 mL). Azobisisobutyronitrile (AIBN, 0.01 g, Aldrich) was added to the flask. The flask was sealed with a rubber septum. Nitrogen was bubbled through the reaction mixture for 30 minutes to purge dissolved oxygen. The flask was then kept at 60° C. with stirring at 300 rpm for 17 hours. After the reaction, 1 g of 4-methoxyphenol (MEHQ) was added to stop the synthesis. The reaction mixture, which was observed to be viscous, was then purified by precipitating in a 1:1 volumetric mixture of acetone:hexane and stirring with three fresh portions of a 1:1 volumetric mixture of acetone:hexane for at least 5 hours, one fresh portion of acetone for at least 5 hours, and three fresh portions of DI water for at least 5 hours. Finally, the terpolymer was dried in a vacuum oven at 60° C. for 48 hours. The composition of the terpolymer was determined using the ratio of protons from the three different monomer units, 1 The composition was calculated from the H-NMR spectrum (FIG. 13). The calculated composition was 15 mol% SEMA, 15 mol% MAETA, and 70 mol% TFEMA. The final conversion of this reaction was 40%.

[0121] Example 13. Formation of thin film composite membranes from PTMS2 In this example, a membrane was prepared using the polymer described in Example 12. The terpolymer (0.5 g) was dissolved in trifluoroethanol (TFE, 9.5 g) at about 25° C. The terpolymer solution was passed through a 0.45 micrometer syringe filter (Whatman) and further degassed in a vacuum oven for at least 1 hour. The membrane was prepared by coating a thin layer of the terpolymer solution onto a commercially available ultrafiltration (UF) membrane using a film applicator rod. A PS35 ultrafiltration membrane purchased from Solecta (Oceanside, CA) was used as the base membrane. After coating, the membrane was immersed in a water bath.

[0122] The thickness and morphology of the membranes were determined by examination of the cryofractured surfaces of the membranes using a scanning electron microscope (SEM, Phenom G2 Pure Tabletop SEM). In FIG. 14, SEM images of the uncoated base membrane (right) and the coated membrane (left) are shown at the same magnification. It can be observed that the coating layer is dense (i.e., free of macroscopic pores) with a thickness of about 0.7 micrometers.

[0123] Example 14. Synthesis of poly(2,2,2-trifluoroethyl methacrylate)-random-poly(2-(methacryloyloxy)ethyl]trimethylammonium chloride)-random-poly(2-sulfoethyl methacrylate) (PTMS3) In this example, a random terpolymer was prepared using three monomer units: 2-sulfoethyl methacrylate (SEMA, Polysciences), [2-(methacryloyloxy)ethyl]trimethylammonium chloride (MAETA, Sigma-Aldrich), and 2,2,2-trifluoroethyl methacrylate (TFEMA, ACROS Organics). The first two monomers were passed through a column of neutral activated alumina (Sigma-Aldrich) to remove inhibitors, and the last monomer was passed through a column of basic activated alumina (Sigma-Aldrich). SEMA (1.59 g, 8.2 mmol), MAETA (1.71 g, 8.2 mmol), and 2,2,2-trifluoroethyl methacrylate (6.70 g, 39.9 mmol) were dissolved in this order in dimethyl sulfoxide (DMSO, 40 mL). Azobisisobutyronitrile (AIBN, 0.01 g, Aldrich) was added to the flask. The flask was sealed with a rubber septum. Nitrogen was bubbled through the reaction mixture for 30 minutes to purge dissolved oxygen. The flask was then kept at 60° C. with stirring at 300 rpm for 17 hours. After the reaction, 1 g of 4-methoxyphenol (MEHQ) was added to stop the synthesis. The reaction mixture, which was observed to be viscous, was then purified by precipitating in DI water and stirring with two fresh portions of DI water for at least 5 hours and two fresh portions of isopropyl alcohol for at least 5 hours. Finally, the terpolymer was dried in a vacuum oven at 60° C. for 48 hours. The composition of the terpolymer was determined using the ratio of protons from the three different monomer units, 1 The composition was calculated from the H-NMR spectrum (FIG. 15). The calculated composition was 11 mol% SEMA, 11 mol% MAETA, and 78 mol% TFEMA. The final conversion of this reaction was 70%.

[0124] Example 15. Formation of thin film composite membrane from PTMS3 In this example, a membrane was prepared using the polymer described in Example 14. The terpolymer (0.5 g) was dissolved in trifluoroethanol (TFE, 9.5 g) at about 25° C. The terpolymer solution was passed through a 0.45 micrometer syringe filter (Whatman) and further degassed in a vacuum oven for at least 1 hour. The membrane was prepared by coating a thin layer of the terpolymer solution onto a commercially available ultrafiltration (UF) membrane using a film applicator rod. A PS35 ultrafiltration membrane purchased from Solecta (Oceanside, CA) was used as the base membrane. After coating, the membrane was immersed in a water bath.

[0125] The thickness and morphology of the membranes were determined by examination of the cryofractured surfaces of the membranes using a scanning electron microscope (SEM, Phenom G2 Pure Tabletop SEM). In FIG. 16, SEM images of the uncoated base membrane (right) and the coated membrane (left) are shown at the same magnification. It can be observed that the coating layer is dense (i.e., free of macroscopic pores) with a thickness of about 0.8 micrometers.

[0126] Example 16. Water permeance of polyampholyte terpolymer membranes In this example, the pure water flux through the membranes described in Examples 2, 4, 6, 8, 10, 13, and 15 was measured using a cell volume of 10 mL and a cell size of 4.1 cm. 2 The measurements were performed using an Amicon 8010 stirred dead-end filtration cell (Millipore) with an effective filtration area of ​​1000 nm. The cell was stirred at 500 rpm and the test was performed at 40 psi. After a stabilization period of at least 1 hour, permeate samples were collected and weighed over a 120-minute period. The resulting values ​​were divided by the filtration area and the duration of the experiment to obtain the flux (or permeate flow rate). The flux values ​​were normalized by pressure to obtain the pure water permeance (Table 1). These membranes have permeance comparable to commercial membranes for nanofiltration and ultrafiltration.

[0127] [Table 1]

[0128] Example 17. Rejection of dyes using polyampholyte terpolymer membranes In this example, membranes prepared as described in Examples 2, 4, 6, 8, 10, 13, and 15 were used in experiments aimed at identifying their effective pore size or size cutoff. Dye molecules were used to investigate this property because they are rigid and their concentration is easily measured by UV-Vis spectroscopy. Retention experiments were performed with a cell volume of 10 mL and a 4.1 cm 2 The experiments were carried out in an Amicon 8010 stirred dead-end filtration cell (Millipore) with an effective filtration area of ​​100 μm. The cell was stirred at 500 rpm and the tests were carried out at 40 psi. The cell was stirred at 500 rpm to minimize concentration polarization effects. After passing pure water through the membrane for at least 1 h, the cell was emptied and a 0.1 mM aqueous solution of the probe dye was placed in the cell. After removing the first 1 mL to avoid contamination with pure water, a sufficient amount was collected for analysis by UV-visible spectrophotometry and the solute rejection (%) was calculated (Table 2). The cell was rinsed several times with water. Pure water was filtered through the membrane until the permeate was completely clear before switching to the new solute.

[0129] [Table 2]

[0130] Example 18. Salt Rejection Using Polyampholyte Terpolymer Membranes In this example, membranes prepared as described in Examples 2, 4, 6, 8, 10, 13, and 15 were used in experiments to determine their salt retention properties. We used different salts at different concentrations to investigate this property, and the concentrations were easily measured by a standard conductivity probe. The retention experiments were performed with a cell volume of 10 mL and a 4.1 cm 2The experiments were carried out in an Amicon 8010 stirred dead-end filtration cell (Millipore) with an effective filtration area of ​​1000 μm. The cell was stirred at 500 rpm and the tests were carried out at 40 psi. The cell was stirred at 500 rpm to minimize concentration polarization effects. After passing pure water through the membrane for at least 1 h, the cell was emptied and an aqueous solution of the probe salt was placed in the cell. After removing the first 1 mL to avoid contamination with pure water, a sufficient volume was collected for analysis by conductivity probe and salt rejection (%) was calculated (Table 3). The cell was rinsed several times with water. Pure water was filtered through the membrane until the permeate volume reached 1 mL before switching to a new salt solution.

[0131] [Table 3]

[0132] Example 19. Fouling resistance of polyampholyte terpolymer membranes In this example, membranes prepared as described in Examples 2, 13, and 15 were used in experiments to determine their fouling resistance. Retention experiments were performed with a cell volume of 10 mL and a 4.1 cm 2 The experiments were carried out in an Amicon 8010 stirred dead-end filtration cell (Millipore) with an effective filtration area of ​​1000 μm. The cell was stirred at 500 rpm.

[0133] In the first test, the feed solution consisted of a 1500 ppm oil-in-water emulsion (9:1 ratio of soybean oil:DC193 surfactant (obtained from Dow-Corning)) prepared by blending the oil, water and surfactant in a blender at high rpm for approximately 3 minutes.

[0134] The second fouling test used lysozyme, a positively charged protein, and the feed solution consisted of a 1 g / L solution of lysozyme in 1x phosphate buffered saline (PBS) buffer. The third fouling test used bovine serum albumin (BSA), a negatively charged protein, and the feed solution consisted of a 1 g / L solution of BSA in 1x phosphate buffered saline (PBS) buffer.

[0135] Example 20. Self-assembly of polyampholyte terpolymer films We document the self-assembled morphology of our r-PAC using transmission electron microscopy (TEM) images and differential scanning calorimetry (DSC) analysis.

[0136] TEM was performed using a Hitachi 7800 transmission electron microscope operated in bright-field mode at 100 keV. To obtain good contrast, ionic domains were preferentially stained by immersion in 2% CuCl2 aqueous solution to form sulfonate-copper complexes. Figure 19 shows bright-field TEM images of PTMS and PTMS-copolymers. A bicontinuous network of percolated ionic nanochannels (dark regions) surrounded by a hydrophobic phase (light regions) was observed for both compositions. Fast Fourier transforms (FFTs) of the TEM images lack directional features (inset in Figure 19), indicating a disordered network. The characteristic length scales indicated by the outer rings of the FFTs are 3.1 nm and 4.5 nm for PTMS and PTMS-, respectively, corresponding to average ionic domain sizes in the dry state of PTMS and PTMS- of 1.55 nm and 2.25 nm, respectively.

[0137] To characterize the phase separation of the copolymers, we utilized DSC, where different glass transition temperatures can be associated with different phase-separated structures. DSC was performed using a TAQ100 series calorimeter (TA Instruments) coupled with a N2 purge and cooling system. 3-5 mg of each polymer was sealed in an aluminum pan and thoroughly dried under N2 in the DSC chamber to determine the T with different water contents. g A regulated heating ramp of 5°C / min was used after the samples were thoroughly dried to avoid T g was taken from the midpoint of the baseline shift.

[0138] Example 21. Rejection of small neutral molecules using polyampholyte terpolymer membranes In this example, membranes prepared as described in Examples 2, 4, 6, 8, 10, 13, and 15 were used in experiments aimed at identifying their effective pore size or size cutoff. Membrane size-based selectivity was determined by filtering a series of small neutral organic solutes at a concentration of 4,000 ppm. Retention experiments were performed using a 10 mL cell volume and 4.1 cm 2 The experiments were carried out in an Amicon 8010 stirred dead-end filtration cell (Millipore) with an effective filtration area of ​​1000 μm. The cell was stirred at 500 rpm and the tests were carried out at 40 psi. The cell was stirred at 500 rpm to minimize concentration polarization effects. After passing pure water through the membrane for at least 1 h, the cell was emptied and an aqueous solution of the probe small molecule at 4,000 ppm was placed in the cell. After removing the first 1 mL to avoid contamination with pure water, a sufficient amount was collected for analysis by UV-visible spectrophotometry using a COD kit (K-7365, CHEMetrics), thus calculating the solute rejection (%) (Table 4). The cell was rinsed several times with water. Pure water was filtered through the membrane until the permeate was completely clear before switching to the new solute.

[0139] [Table 4] References

[0140] 1. Ekblad, T.; Bergstroem, G.; Ederth, T.; Conlan, S. L.; Mutton, R.; Clare, A. S.; Wang, S.; Liu, Y. L.; Zhao, Q.; D'Souza, F.; Donnelly, G. T.; Willemsen, P. R.; Pettitt, M. E.; Callow, M. E.; Callow, J. A.; Liedberg, B., Poly(ethylene glycol)-Containing Hydrogel Surfaces for Antifouling Applications in Marine and Freshwater Environments. Biomacromolecules 2008, 9 (10), 2775-2783. 2. Grozea, C. M.; Walker, G. C., Approaches in designing non-toxic polymer surfaces to deter marine biofouling. Soft Matter 2009, 5 (21), 4088-4100. 3. Lejars, M.; Margaillan, A.; Bressy, C., Fouling release coatings: a nontoxic alternative to biocidal antifouling coatings. Chemical reviews 2012, 112 (8), 4347-4390. 4. Callow, J. A.; Callow, M. E., Trends in the development of environmentally friendly fouling-resistant marine coatings. Nature Communications 2011, 2, 244. 5. Wang, Z.; Hou, D.; Lin, S., Composite Membrane with Underwater-Oleophobic Surface for Anti-Oil-Fouling Membrane Distillation. 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Experimental Thermal and Fluid Science 1997, 14 (4), 375-381. 11. Li, H.; Hsieh, M.-K.; Chien, S.-H.; Monnell, J. D.; Dzombak, D. A.; Vidic, R. D., Control of mineral scale deposition in cooling systems using secondary-treated municipal wastewater. Water research 2011, 45 (2), 748-760. 12. Rosmaninho, R.; Santos, O.; Nylander, T.; Paulsson, M.; Beuf, M.; Benezech, T.; Yiantsios, S.; Andritsos, N.; Karabelas, A.; Rizzo, G., Modified stainless steel surfaces targeted to reduce fouling-Evaluation of fouling by milk components. Journal of Food Engineering 2007, 80 (4), 1176-1187. 13. Guo, W. S.; Ngo, H. H.; Li, J. X., A mini-review on membrane fouling. Bioresource Technology 2012, 122, 27-34. 14. Flemming, H. C.; Schaule, G.; Griebe, T.; Schmitt, J.; Tamachkiarowa, A., Biofouling - the Achilles heel of membrane processes. Desalination 1997, 113, 215-225. 15. Paul, D., Reverse osmosis: scaling, fouling and chemical attack. Desal Water Reuse 1991, 1, 8-11. 16. Fane, A. G.; Fell, C. J. D., A review of fouling and fouling control in ultrafiltration. Desalination 1987, 62, 117-136. 17. Pervov, A. G., Scale Formation Prognosis and Cleaning Procedure Schedules in Reverse-Osmosis Systems Operation. Desalination 1991, 83 (1-3), 77-118. 18. Holmlin, R. E.; Chen, X. X.; Chapman, R. G.; Takayama, S.; Whitesides, G. M., Zwitterionic SAMs that resist nonspecific adsorption of protein from aqueous buffer. Langmuir 2001, 17 (9), 2841-2850. 19. Ostuni, E.; Chapman, R. G.; Holmlin, R. E.; Takayama, S.; Whitesides, G. M., A survey of structure-property relationships of surfaces that resist the adsorption of protein. Langmuir 2001, 17 (18), 5605-5620. 20. Luk, Y. Y.; Kato, M.; Mrksich, M., Self-assembled monolayers of alkanethiolates presenting mannitol groups are inert to protein adsorption and cell attachment. Langmuir 2000, 16 (24), 9604-9608. 21. Statz, A. R.; Barron, A. E.; Messersmith, P. B., Protein, cell and bacterial fouling resistance of polypeptoid-modified surfaces: effect of side-chain chemistry. Soft Matter 2008, 4 (1), 131-139. 22. Statz, A. R.; Meagher, R. J.; Barron, A. E.; Messersmith, P. B., New peptidomimetic polymers for antifouling surfaces. Journal of the American Chemical Society 2005, 127 (22), 7972-7973. 23. Zhang, Z.; Chao, T.; Chen, S. F.; Jiang, S. Y., Superlow fouling sulfobetaine and carboxybetaine polymers on glass slides. Langmuir 2006, 22 (24), 10072-10077. 24. Zhang, Z.; Chen, S. F.; Chang, Y.; Jiang, S. Y., Surface grafted sulfobetaine polymers via atom transfer radical polymerization as superlow fouling coatings. Journal of Physical Chemistry B 2006, 110 (22), 10799-10804. 25. Barcellona, M. N.; Johnson, N.; Bernards, M. T., Characterizing Drug Release from Nonfouling Polyampholyte Hydrogels. Langmuir 2015, 31 (49), 13402-9. 26. 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Y., Improved antifouling property of zwitterionic ultrafiltration membrane composed of acrylonitrile and sulfobetaine copolymer. Journal of Membrane Science 2006, 285 (1-2), 299-305. 31. Kitano, H.; Imai, M.; Gemmei-Ide, M.; Takaha, K., Raman spectroscopic study on the structure of water in aqueous solution of zwitterionic surfactants. Journal of Colloid and Interface Science 2004, 269 (2), 459-465. 32. Straub, A. P.; Asa, E.; Zhang, W.; Nguyen, T. H.; Herzberg, M., In-situ graft-polymerization modification of commercial ultrafiltration membranes for long-term fouling resistance in a pilot-scale membrane bioreactor. Chem Eng J 2020, 382. 33. Bengani, P.; Kou, Y. M.; Asatekin, A., Zwitterionic copolymer self-assembly for fouling resistant, high flux membranes with size-based small molecule selectivity. Journal of Membrane Science 2015, 493, 755-765. 34. Bengani-Lutz, P.; Converse, E.; Cebe, P.; Asatekin, A., Self-Assembling Zwitterionic Copolymers as Membrane Selective Layers with Excellent Fouling Resistance: Effect of Zwitterion Chemistry. Acs Appl Mater Inter 2017, 9 (24), 20859-20872. 35. Bengani, P.; Kou, Y.; Asatekin, A., Zwitterionic copolymer self-assembly for fouling resistant, high flux membranes with size-based small molecule selectivity. Journal of Membrane Science 2015, 493, 755-765. 36. Bengani-Lutz, P.; Zaf, R. D.; Culfaz-Emecen, P. Z.; Asatekin, A., Extremely fouling resistant zwitterionic copolymer membranes with ~ 1nm pore size for treating municipal, oily and textile wastewater streams. Journal of Membrane Science 2017, 543 (Supplement C), 184-194. 37. Asatekin Alexiou, A.; Bengani, P. Zwitterion Containing Membranes. U.S. Patent 10,150,088, 2018; incorporated by reference. 38. Louder, SJ; Asatekin, A., Zwitterionic Ion-Selective Membranes with Tunable Subnanometer Pores and Excellent Fouling Resistance. 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[0141] Incorporation by Reference All U.S. patents and U.S. and PCT patent application publications referred to herein are hereby incorporated by reference. In the case of conflict, the present application, including definitions herein, will control.

[0142] Equivalent The foregoing specification is believed to be sufficient to enable one skilled in the art to practice the present invention. The present invention is not limited in scope by the examples provided, as the examples are intended as merely illustrative of one aspect of the invention, and other functionally equivalent embodiments are within the scope of the present invention. Various modifications of the present invention, in addition to those shown and described herein, will become apparent to those skilled in the art from the foregoing description and are included within the scope of the appended claims. The advantages and objectives of the present invention are not necessarily encompassed by each embodiment of the present invention.

Claims

**Claim 1** A polymer comprising: (a) a plurality of hydrophobic repeating units; (b) a plurality of cationic repeating units; and (c) a plurality of anionic repeating units wherein the hydrophobic repeating units, the cationic repeating units, and the anionic repeating units are in a random or statistical order. **Claim 2** The polymer according to claim 1, which is insoluble in water. **Claim 3** The polymer according to claim 1, wherein the molar ratio of cationic repeating units to anionic repeating units is from about 1.1:1 to about 1:1.

1. **Claim 4** The polymer according to claim 1, wherein the molar ratio of cationic repeating units to anionic repeating units is about 1:

1. **Claim 5** The polymer according to claim 1, wherein the net charge of the polymer is from -10 to +10. **Claim 6** The polymer according to claim 1, wherein the molar ratio of cationic repeating units to anionic repeating units is greater than about 1:

1. **Claim 7** The polymer according to claim 6, wherein the net charge of the polymer is positive. **Claim 8** The polymer according to claim 1, wherein the molar ratio of cationic repeating units to anionic repeating units is less than about 1:

1. **Claim 9** The polymer according to claim 8, wherein the net charge of the polymer is negative. **Claim 10** The polymer according to claim 1, wherein the molecular weight of the polymer is greater than about 20,000 g / mol. **Claim 11** The polymer according to claim 10, wherein the molecular weight of the polymer is greater than about 100,000 g / mol. **Claim 12** The polymer according to claim 1, wherein the plurality of hydrophobic repeating units constitute at least about 30% by weight of the polymer. **Claim 13** The polymer according to claim 12, wherein the plurality of hydrophobic repeating units constitute from about 40% to about 90% by weight of the polymer. **Claim 14** The polymer according to claim 1, wherein the plurality of cationic repeating units and the plurality of anionic repeating units each constitute at least about 0.5% by weight of the polymer. **Claim 15** The polymer according to claim 1, wherein the plurality of cationic repeating units and the plurality of anionic repeating units each constitute from about 0.5% to about 30% by weight of the polymer. **Claim 16** The polymer according to claim 1, wherein each hydrophobic repeating unit is independently selected from the group consisting of 2,2,2-trifluoroethyl methacrylate (TFEMA), fluorinated acrylate, methacrylate, pentafluoropropyl methacrylate, heptafluorobutyl methacrylate, pentafluorophenyl methacrylate, styrene, methyl methacrylate, and acrylonitrile.

17. The polymer according to claim 1, wherein each hydrophobic repeating unit is the same and is selected from the group consisting of 2,2,2-trifluoroethyl methacrylate (TFEMA), fluorinated acrylate, methacrylate, pentafluoropropyl methacrylate, heptafluorobutyl methacrylate, pentafluorophenyl methacrylate, styrene, methyl methacrylate, and acrylonitrile.

18. The polymer according to claim 17, wherein the hydrophobic repeating unit is 2,2,2-trifluoroethyl methacrylate (TFEMA).

19. The polymer according to claim 1, wherein each anionic repeating unit is a methacrylate, acrylate, methacrylamide, acrylamide, styrene or vinyl derivative containing a carboxylic acid, sulfonate, phosphate, or other ionizable group or charged group.

20. The polymer according to claim 1, wherein the anionic repeating unit is selected from the group consisting of methacrylic acid (MAA), 2-sulfoethyl methacrylate (SEMA), and L-tryptophan-methacrylamide (L-Try-MA).

21. The polymer according to claim 1, wherein each cationic repeating unit is a methacrylate, acrylate, methacrylamide, acrylamide, styrene or vinyl derivative containing an amine, ammonium, pyridinium, imidazolium, phosphonium, pyrrolidinium, or other ionizable group or charged group.

22. The polymer according to claim 1, wherein the cationic repeating unit is 2-(methacryloyloxy)ethyl]trimethylammonium chloride (MAETA).

23. The polymer according to claim 1, wherein the cationic repeating unit contains a quaternary ammonium group.

24. A thin-film composite membrane comprising a porous substrate and a selective layer containing the polymer according to any one of claims 1 to 23, wherein an average effective pore diameter of the porous substrate is larger than an average effective pore diameter of the selective layer, and the selective layer is disposed on a surface of the porous substrate.

25. The thin-film composite membrane according to claim 24, wherein the selective layer has a thickness of about 10 nm to about 10 μm.

26. The thin-film composite membrane according to claim 24, wherein the selective layer has an average effective pore diameter of about 0.1 nm to about 2.0 nm.

27. The net charge of the polymer is positive, and the thin-film composite membrane blocks positively charged solutes and salts, or The net charge of the polymer is negative, and the thin-film composite membrane blocks negatively charged solutes and salts. The thin-film composite membrane according to claim 24.

28. The net charge of the polymer is -10 to +10, and the selective layer exhibits size-based selectivity among uncharged organic molecules. The thin-film composite membrane according to claim 24.

29. The thin-film composite membrane according to claim 28, wherein the selective layer exhibits a rejection rate of about 95% or more or about 99% or more with respect to neutral molecules having a hydration diameter of about 1.5 nm or more.

30. The thin-film composite membrane according to claim 24, wherein the selective layer exhibits anti-fouling properties.

31. The selective layer exhibits resistance to fouling by an oil emulsion, or The selective layer exhibits resistance to fouling by adsorption of a biopolymer. The thin-film composite membrane according to claim 24.

32. A method for purifying a peptide or a protein, comprising contacting the thin-film composite membrane according to claim 24 with a mixture containing one or more peptides or proteins at a first flow rate, whereby a part of the mixture is retained by the thin-film composite membrane.

33. A method for removing an organic solute from water, comprising contacting the thin-film composite membrane according to claim 24 with an aqueous solution containing an organic solute at a first flow rate, whereby the organic solute is retained by the thin-film composite membrane.

34. A method for decontaminating water, comprising contacting the thin-film composite membrane according to claim 24 with a mixture containing water and one or more contaminants at a first flow rate, whereby one or more contaminants are retained by the thin-film composite membrane.

35. A method of size-selective separation, comprising contacting, at a first flow rate, the thin film composite membrane according to claim 24 with a mixture comprising one or more particles of different sizes, whereby one or more particles of a specific size are retained by the thin film composite membrane.

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