Patent Description:
Membranes comprising fluoropolymers are being considered for filtering a variety of fluids, for example, for removing trace metal impurities from microelectronics fluids. Some of these membranes are characterized by low surface energy values or critical wetting surface tension (CWST) values and/or high resistance to organic solvents and aggressive chemicals. Despite the one or more of the advantages of these membranes, there exists a need for fluoropolymers and membranes comprising such fluoropolymers with improved properties such as low CWST values and/or increased resistance to organic solvents and/or aggressive chemicals.

In the scientific publication of <NPL>, the preparation of <NUM>,<NUM>,<NUM>,<NUM>-perfluorooctyloxymethylstyrene is disclosed as well as the copolymerization of the same with chloromethylstyrene.

The scientific publication of <NPL>, relates to membranes for fuel cells based on polymeric materials containing cationic groups.

A process for the preparation of a microporous polymeric membrane is disclosed in <CIT>. The process includes polymerizing a polymerizable fluorine-containing monomer in the presence of a microporous polymeric membrane substrate such that the fluorine-containing monomer forms a polymeric substrate that is permanently chemically bonded to all surfaces of the membrane.

Comb-like fluorinated polystyrene polymers and films made of such polymers are disclosed in the scientific article of <NPL>.

The invention provides fluoropolymers with low CWST values and membranes made from the fluoropolymers. In an embodiment, the invention provides a copolymer comprising polymerized monomeric units I and II,.

The copolymer is a superhydrophobic polymer and can be used to impart oleophobic properties material surfaces, i.e., a surface tension of below <NUM> dynes/cm. The invention also provides a method of preparing a porous membrane comprising the copolymer disposed on a porous support. The invention further provides a method of filtering fluids, particularly microelectronics fluids to a concentration below <NUM> ppb, preferably below <NUM> ppb or below detection limit of most instruments.

In accordance with an embodiment, the invention provides a copolymer comprising polymerized monomeric units I and II,.

In an embodiment of the copolymer, n = <NUM>, <NUM>, or <NUM>, particularly <NUM>.

In any of the above embodiments, x = <NUM>, <NUM>, <NUM>, <NUM>, or <NUM>, particularly <NUM>.

In any of the above embodiments, the monomeric unit II is chloroalkyl styrene, particularly chloromethyl styrene. The haloalkyl, or chloroalkyl, can be meta or para substituted on styrene, or monomer II can be a mixture of meta and para substituted haloalkyl styrenes.

The perfluoroalkyl group can be present on the phenyl ring of B in any suitable position, ortho, meta, or para, preferably meta or para positions, or a mixture of o, m, and/or para isomers can be used. Herein, "p/m" designates a mixture of para and meta isomers.

In any of the above embodiments, the copolymer is a block copolymer, for example, a diblock, a triblock, or a multiblock copolymer, or a random copolymer.

The "alkyl" group could be linear or branched. In accordance with an embodiment, the alkyl group is preferably a C<NUM>-C<NUM> alkyl. Examples of alkyl group include methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, n-hexyl, hexadecyl, and the like. This definition also applies wherever "alkyl" occurs such as in hydroxyalkyl, monohalo alkyl, dihalo alkyl, and trihalo alkyl. The C<NUM>-C<NUM> alkyl group can also be further substituted with a cycloalkyl group, e.g., a C<NUM>-C<NUM> cycloalkyl group.

In accordance with an embodiment, the "alkoxy" group is preferably a C<NUM>-C<NUM> alkoxy. Examples of alkoxy group include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, sec-butoxy, isobutoxy, tert-butoxy, n-pentoxy, isopentoxy, n-hexoxy, hexadecyloxy, and the like.

The term "halo" refers to a halogen selected from the group consisting of fluorine, chlorine, bromine, and iodine, preferably chlorine.

Whenever a range of the number of atoms in a structure is indicated (e.g., a C<NUM>-<NUM>, a C<NUM>-<NUM>, C<NUM>-<NUM>, C<NUM>-<NUM>, or C<NUM>-<NUM> alkyl, alkoxy, etc.), it is specifically contemplated that any sub-range or individual number of carbon atoms falling within the indicated range also can be used. Thus, for instance, the recitation of a range of <NUM>-<NUM> carbon atoms (e.g., C<NUM>-C<NUM>), <NUM>-<NUM> carbon atoms (e.g., C<NUM>-C<NUM>), <NUM>-<NUM> carbon atoms (e.g., C<NUM>-C<NUM>), <NUM>-<NUM> carbon atoms(e.g., C<NUM>-C<NUM>), <NUM>-<NUM> carbon atoms(e.g., C<NUM>-C<NUM>), <NUM>-<NUM> carbon atoms(e.g., C<NUM>-C<NUM>), <NUM>-<NUM> carbon atoms(e.g., C<NUM>-C<NUM>), <NUM>-<NUM> carbon atoms(e.g., C<NUM>-C<NUM>),, <NUM>-<NUM> carbon atoms (e.g., C<NUM>-C<NUM>), <NUM>-<NUM> carbon atoms (e.g., C<NUM>-C<NUM>), <NUM>-<NUM> carbon atoms (e.g., C<NUM>-C<NUM>), or <NUM>-<NUM> carbon atoms (e.g., C<NUM>-C<NUM>) as used with respect to any chemical group (e.g., alkyl, alkoxy, etc.) referenced herein encompasses and specifically describes <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> carbon atoms, as appropriate, as well as any sub-range thereof, e.g., <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, and <NUM>-<NUM> carbon atoms, and anything in between such as <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, and <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, and <NUM>-<NUM> carbon atoms, and <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, <NUM>-<NUM> carbon atoms, etc., as appropriate.

In an embodiment, the copolymer is selected from the group consisting of a copolymer of para and/or meta substituted [[(perfluorohexyl)ethylene]thiomethyl]-styrene and a haloalkyl styrene monomer; a copolymer of poly[p/m-[[(perfluorohexyl)ethylene]thiomethyl]-styrene and poly [chloromethylstyrene].

In accordance with an embodiment of the invention, segment A-X-CH<NUM> comprises a monomer selected from the group consisting of <NUM>-(perfluorooctyl)ethyl thiol, <NUM>-(perfluorohexyl)ethyl thiol and formula A-X-CH<NUM>-B corresponds to para and/or meta substituted [[(perfluorohexyl)ethylene]thiomethyl]-styrene. Without wishing to be bound by any particular theory or mechanism, the perfluorohydrocarbon provides oleophobic properties and improved adherence to the substrate.

In an embodiment, segment B comprises styrene and a halogen group, wherein the halogen group is chlorine. In another embodiment, segment B comprises a monomer selected from the group consisting of <NUM>-vinylbenzyl chloride, <NUM>-vinylbenzyl chloride, <NUM>,<NUM>-vinylbenzyl chloride. The double bond in the styrene-group makes polymerization with other polymers easier and, due to the halogen group, which can be substituted with other functionalities, the styrene can be easily modifiable with one or more of a variety of functional groups, including positive- and/or negative-charged groups.

The copolymers can be prepared by any suitable technique. For example, a block copolymer can be prepared as illustrated in Scheme <NUM>, and a random copolymer can be prepared as illustrated in Scheme <NUM>. <CHM>
<CHM>
Subsequently one or more of the Cl substituents is/are replaced as set out in claim <NUM>.

In an embodiment, the random copolymer can be synthesized by mixing <NUM> equivalents of <NUM>-para or <NUM>,<NUM>-para-mata-chloromethyl styrene with <NUM> equivalent of para or p, m-[[(perfluorohexyl)ethylene]thiomethyl]-styrene in toluene at a suitable concentration, e.g., <NUM>% by wt. , of the p, m-[[(perfluorohexyl)ethylene]thiomethyl]-styrene. <NUM> mol % of azobisisobutyronitrile (AIBN) is then added and mixture is degassed for <NUM> minutes, following which, the reaction mixture is stirred at suitable temperature, e.g., <NUM> degrees centigrade, for a suitable time, e.g., <NUM> hours. The reaction mixture is cooled and is diluted with acetone. The product obtained is precipitated in methanol and mixed for <NUM> hours. The solvent is decanted and the precipitate is redissolved in acetone. The product in acetone is reprecipitated in fresh methanol and filtered using a coarse fritted funnel, washed with methanol, and dried in a vacuum oven overnight.

In an embodiment, the number average molecular weight of the random copolymer is about 1KDa to about <NUM> KDa, for example <NUM> KDa to about <NUM> KDa, and particularly about <NUM> KDa. In an embodiment, the number average molecular weight is <NUM> KDa. The number average molecular weight is determined by the use of GPC.

The block copolymer can be synthesized by any suitable process, including, e.g., atom transfer radical polymerization (ATRP), iodine transfer polymerization (ITP), anionic polymerization and other forms of nitroxide mediated radical polymerization (NMP).

The number average molecular weight of the block copolymer is about 1KDa to about <NUM> KDa, particularly <NUM> KDa to about <NUM> KDa, and more particularly about <NUM> KDa. While the molecular weight of the block copolymer would depend upon the duration of polymerization, the average molecular weight for the block is around <NUM> KDa for an <NUM> hours run.

The present invention further provides a porous membrane comprising any of the copolymers described above disposed on a porous support, e.g., a porous polymeric support.

In an embodiment, the porous polymeric support is selected from PVC/PAN, polysulfone, polyethersulfone, HDPE, PET, PPS, PPSU (polyphenyl sulfone), PTFE, PVDF, PVF (polyvinyl fluoride), PCTFE (polychlorotrifluoroethylene), FEP (fluorinated ethylene-propylene), ETFE (polyethylenetetrafluoroethylene), ECTFE (poly ethylenechlorotrifluoroethylene), PFPE (perfluoropolyether), PFSA (perfluorosulfonic acid), and perfluoropolyoxetane.

The present invention further provides a method of preparing a porous membrane comprising a copolymer as described above, the method comprising, in an embodiment:.

When the halo group is replaced with a substituent, as indicated above, the resulting copolymer has a higher surface tension value, for example, up to about <NUM> mN/m (<NUM> dynes/cm), particularly from about <NUM> to <NUM> mN/m (<NUM> to about <NUM> dynes/cm).

The replacement can be carried out by any suitable method. For example, porous membrane obtained at the end of step (iv) can be soaked for a suitable period of time in a solution of the modifying agent, e.g., iminodisuccinic acid (IDSA), in a mixture of water, NaOH, and DMF. The solution can be heated to <NUM>. The membrane is then washed with water and isopropanol (IPA) and dried. The membrane is then soaked in HCl, rinsed with IPA, and dried.

In an embodiment, IDSA (<NUM>) is dissolved in a mixture of water (<NUM>), <NUM> NaOH (<NUM>) and DMF (<NUM>). The mixture is poured over membranes pre-wet with DMF in a petri dish. The membranes are heated to <NUM> overnight, rinsed with copious amount of water and then IPA. Afterwards, the membranes are dried at <NUM>° for <NUM> hr. The membranes are soaked in <NUM>% HCl for two hours, rinsed with water and IPA for <NUM> hour, and dried again at <NUM> for <NUM> minutes. Surface tension of the membranes range from <NUM>-<NUM> dynes/cm.

In another embodiment, iminodiacetic acid (IDA) (<NUM>) is dissolved in a mixture of water (<NUM>), <NUM> NaOH (<NUM>) and DMF (<NUM>). The mixture is then poured over membranes pre-wet with DMF in a petri dish. Membranes are heated to <NUM> overnight, rinsed with copious amount of water and then IPA. Afterwards, the membranes are dried at <NUM>° for <NUM> hr. Membranes are soaked in <NUM>% HCl for two hours, and rinsed with water and IPA, then dried again at <NUM> for <NUM> minutes. Surface tension of the resulting membranes range from <NUM> to <NUM> mN/m (<NUM>-<NUM> dynes/cm).

In yet another embodiment, triethylamine (TEA) <NUM>% in water <NUM> (mL) is mixed with IPA (<NUM>), and poly(pfotms-ran-cms) coated <NUM> PTFE with CWST of <NUM> mN/m (<NUM> dynes/cm) is immersed in the solution overnight at room temperature. Afterwards, membrane is rinsed in copious amount of water and then soaked in IPA overnight. Membrane is dried at <NUM> for <NUM> minutes, and surface tension is measured. CWST is <NUM> mN/m (<NUM> dynes/cm).

In another embodiment, the invention provides a method of preparing a porous membrane comprising a copolymer as described above, the method comprising:.

The porous membrane can be oleophobic, particularly an oleophobic membrane with a CWST of about <NUM> mN/m (<NUM> dynes/cm) or less, e.g., <NUM> or <NUM> mN/m (<NUM> or <NUM> dynes/cm). The porous membrane can be, e.g., a functionally-as-made membrane, comprising the copolymer film or fiber without a porous support; or it can be a porous support coated with the copolymer.

CWST can be measured by a suitable method. In an embodiment, the method relies on a set of solutions of certain composition. Each solution has specific surface tension. The solutions surface tension ranges from <NUM> to <NUM> mN/m (<NUM> to <NUM> dynes/cm) in small non-equivalent increments. To measure membrane surface tension, it is positioned on to top of white light table, one drop of a solution of certain surface tension is applied to the porous membrane surface and the time the drop takes to penetrate through the porous membrane and become bright white as an indication of light going through the porous membrane is recorded. Instant wetting is considered when the time the drop takes to penetrate the porous membrane is ≤ <NUM> seconds. If the time > <NUM> seconds, the solution is considered to partially wet the porous membrane.

In accordance with an embodiment of the invention, the porous membrane is a porous membrane, e.g., a nanoporous membrane, for example, a porous membrane having pores of diameter between <NUM> and <NUM>, or a microporous membrane having pores of diameter between <NUM> and <NUM>.

The porous membrane is a functionalized membrane comprising one or more added functional groups on the copolymer. The porous membrane can be, e.g., a charged membrane. Functionalization of the copolymer membrane can result in a CWST up to about <NUM> mN/m (<NUM> dynes/cm). Functional groups include, e.g., a cation, an anion, or a polar group.

In accordance with embodiments of the invention, the porous membrane can have a variety of configurations, including planar, flat sheet, pleated, tubular, spiral, and hollow fiber. In one embodiment, the porous membrane is a hollow-fiber membrane.

Porous membranes according to embodiments of the invention are typically disposed in a housing comprising at least one inlet and at least one outlet and defining at least one fluid flow path between the inlet and the outlet, wherein at least one inventive membrane or a filter including at least one inventive membrane is across the fluid flow path, to provide a filter device or filter module. In an embodiment, a filter device is provided comprising a housing comprising an inlet and a first outlet, and defining a first fluid flow path between the inlet and the first outlet; and at least one inventive membrane or a filter comprising at least one inventive membrane, the inventive membrane or filter comprising at least one inventive membrane being disposed in the housing across the first fluid flow path.

Preferably, for crossflow applications, at least one inventive membrane or filter comprising at least one inventive membrane is disposed in a housing comprising at least one inlet and at least two outlets and defining at least a first fluid flow path between the inlet and the first outlet, and a second fluid flow path between the inlet and the second outlet, wherein the inventive membrane or filter comprising at least one inventive membrane is across the first fluid flow path, to provide a filter device or filter module. In an illustrative embodiment, the filter device comprises a crossflow filter module, the housing comprising an inlet, a first outlet comprising a concentrate outlet, and a second outlet comprising a permeate outlet, and defining a first fluid flow path between the inlet and the first outlet, and a second fluid flow path between the inlet and the second outlet, wherein at least one inventive membrane or filter comprising at least one inventive membrane is disposed across the first fluid flow path.

The filter device or module may be sterilizable. Any housing of suitable shape and providing an inlet and one or more outlets may be employed.

The housing can be fabricated from any suitable rigid impervious material, including any impervious thermoplastic material, which is compatible with the fluid being processed. For example, the housing can be fabricated from a metal, such as stainless steel, or from a polymer, e.g., transparent or translucent polymer, such as an acrylic, polypropylene, polystyrene, or a polycarbonate resin.

A porous membrane can be a functionally-as-made membrane ("FAM Membrane"), which can be prepared, for example, as illustrated in <FIG> for reference, by blending of poly(pftoms-ran-cms) with a second polymer, e.g., PVC-AN, in THF and stirring at <NUM> rpm for <NUM>, then adding dissolvable particles, such as NaHCO<NUM> particles, that achieve the desired pore size into solution and stirring at <NUM> rpm for <NUM>. This mixture is then cast onto a PET substrate on a glass plate. After slow evaporation of THF at room temperature, membrane is soaked in a dilute HCl solution over night to remove particles. The resulting membrane is dried at a suitable temperature, e.g., <NUM> °C to <NUM> °C, in particular <NUM> °C, depending on the boiling point of the solvent, in an oven or at room temperature for a suitable time to remove the solvent, for example, <NUM>.

Suitable second polymers include PVC-AN, HDPE, PET, PPS, PPSU (polyphenyl sulfone), PTFE, PVDF, PVF (polyvinyl fluoride), PCTFE (polychlorotrifluoroethylene), FEP (fluorinated ethylene-propylene), ETFE (polyethylenetetrafluoroethylene), ECTFE (poly ethylenechlorotrifluoroethylene), PFPE (perfluoropolyether), PFSA (perfluorosulfonic acid), and perfluoropolyoxetane.

Other dissolvable or removable particles which can be used in the method above include potassium carbonate, zeolite, cellulose, soluble fibers, silica particles, and nanoparticles; example zinc oxide.

The porous membrane can comprise the copolymer in one of many ways. For example, the porous membrane may include a coating comprising the copolymer. The coated membrane can be made, for example, by membrane coating, which is performed by dissolving <NUM>% copolymer in acetone and membrane is dipped in the polymer solution for <NUM> seconds. The resulting membrane is dried in an oven at a suitable temperature, e.g., <NUM>, for about <NUM> minutes, and the porous membrane is soaked in IPA for about <NUM> hours, dried in an oven for <NUM> minutes at <NUM>, and surface tension and weight gain is measured. SEM micrographs of examples of membranes are depicted in <FIG>.

The porous membrane is modified to include one or more functional groups. A general scheme for constructing a functionalized membrane is shown in <FIG>. The porous membrane can be functionalized with a charged group. For example, in one embodiment, the porous membrane is functionalized with an anionic group. Preparation of the anionic membrane includes, e.g., dissolving EDTA (<NUM>) in a mixture of water (<NUM>), <NUM> NaOH (<NUM>), and DMF (<NUM>). The mixture is then poured over membranes which had been pre-wet with DMF in a Petri dish. Membranes are heated to <NUM> overnight, rinsed with copious amount of water and then IPA. The porous membranes are dried at <NUM> for <NUM> hr and soaked in <NUM>% HCl for two hours, and rinsed with water and IPA, then dried again at <NUM> for <NUM> minutes. Surface tension of membranes ranged from <NUM>-<NUM> dynes/cm. Membranes obtained in this method removed <NUM>% of most trace metals from isopropyl alcohol.

The fluorinated chain must be present in at least <NUM>% by volume of the polymer in order to impart oleophobicity to the porous membrane.

Additionally, the volume ratio of the perfluoro-styrene block in the random copolymer must not be greater than <NUM>% for the polymer to be soluble in non-fluorinated solvents.

In another embodiment, the porous membrane is functionalized with a cationic group which can be prepared by, e.g., by mixing triethylamine <NUM>% in water <NUM> (mL) with IPA (<NUM>), and immersing a porous membrane, e.g., PTFE, in the mixture overnight at room temperature. Afterwards, membrane is rinsed with water and soaked in IPA overnight. Membrane is dried at <NUM> for <NUM> minutes, and surface tension is measured. CWST was <NUM> mN/m (<NUM> dynes/cm).

The present invention includes the following embodiments, but not limited to:.

The porous membrane, according to embodiments of the invention, can be used in a variety of applications, including, for example, diagnostic applications (including, for example, sample preparation and/or diagnostic lateral flow devices), inkjet applications, lithography, e.g., as replacement for HD/UHMW PE based media, filtering fluids for the pharmaceutical industry, metal removal, production of ultrapure water, treatment of industrial and surface waters, filtering fluids for medical applications (including for home and/or for patient use, e.g., intravenous applications, also including, for example, filtering biological fluids such as blood (e.g., virus removal)), filtering fluids for the electronics industry (e.g., filtering photoresist fluids in the microelectronics industry and hot SPM), filtering fluids for the food and beverage industry, beer filtration, clarification, filtering antibody- and/or protein-containing fluids, filtering nucleic acid-containing fluids, cell detection (including in situ), cell harvesting, and/or filtering cell culture fluids. Alternatively, or additionally, the porous membranes according to embodiments of the invention can be used to filter air and/or gas and/or can be used for venting applications (e.g., allowing air and/or gas, but not liquid, to pass therethrough). Porous membranes according to embodiments of the inventions can be used in a variety of devices, including surgical devices and products, such as, for example, ophthalmic surgical products.

The present invention further provides a method of filtering a fluid, the method comprising passing the fluid through ant of the porous membranes described above. For example, trace metal impurities continue to pose a problem in the manufacture of next generation semiconductor and microelectronics materials. One embodiment of the invention comprises a method of removing metals from a fluid, particularly a microelectronics fluid, by passing the metal-containing fluid through a porous membrane including the copolymer and removing the metals from the fluid. In one embodiment, the inventive method includes passing the metal-containing fluid through a functionalized porous membrane including the copolymer and a functional group and removing the metals from the fluid. The functionalized membrane can remove about <NUM>% of most trace metals from the fluid.

Examples of trace metals include Li, Na, K (and other Group <NUM> metals); Mg, Ca (and other Group <NUM> metals); Al (and other Group <NUM> metals), Pb (and other Group <NUM> metals), Sb, Bi (and other Group <NUM> metals), and Cd, Cr, Mo, Pd, Ag, W, V, Mn, Fe, Ni, Cu, Zn (and other Transition metals).

Advantageously, the copolymer can impart oleophobic properties to a material, such as, e.g., a porous membrane, providing a surface tension of <NUM> mN/m (<NUM> dynes/cm) or less on the material without the need for post-treatment. A porous membrane, including the copolymer, is stable in acids, bases, organic solvents, oxidizers, and stable at high temperatures and against gamma irradiation. High water breakthrough pressures and air flow rates can be achieved in the porous membrane, and it can be easily functionalized, such as, e.g., with cationic and anionic groups.

The porous membrane can be used to remove trace metals, for example, so that the filtrate has a concentration of <NUM> ppb or down to the detection limit of the instrument, from water and organic fluids in many applications, such as, e.g., those in the microelectronics industry. In an embodiment, the fluid being treated contains <NUM> ppb or more of a trace metal, and the filtrate has a trace metal concentration of <NUM> ppb.

This example illustrates the preparation of a random copolymer of p-[[(perfluorohexyl)ethylene]thiomethyl]-styrene and chloromethyl styrene (poly(pfotms-ran-cms)), in accordance with an embodiment of the invention.

In a <NUM> oven dried round bottom flask was mixed perfluorohexyl ethyl thiomethyl styrene (<NUM>, <NUM> mmol), <NUM>-chloromethyl styrene <NUM>, <NUM> mmol, <NUM> equivalent), toluene (<NUM>) and AIBN (<NUM>, <NUM> mmol, <NUM> mol% ). The reaction mixture was degassed with nitrogen gas at <NUM>OC for <NUM> minutes, and stirred at <NUM>OC for <NUM> hours, after which reaction mixture was cooled and <NUM> acetone was added. The copolymer product was precipitated in methanol (<NUM>) and mixed for <NUM> hours. The solvent was decanted and the precipitate was redissolved in acetone (<NUM>). The product in acetone was reprecipitated in fresh methanol (<NUM>), filtered, washed with methanol (<NUM>), and dried in vacuum oven overnight. The resulting copolymer weighed <NUM>. <NUM>H NMR spectrum confirmed the structure of the copolymer:.

A random copolymer of p-[[(perfluorooctyl)ethylene]thiomethyl]-styrene and chloromethylstyrene, ((poly(pfdtms-ran-cms)) was also synthesized using the same procedure.

This example illustrates the preparation of membranes from poly(pfotms-ran-cms), in accordance with an embodiment of the invention.

The random copolymer was dissolved in acetone and cast on a porous support. Thus, <NUM>% copolymer solution in acetone was prepared and a porous support, either PTFE or PES, was dipped in the copolymer solution for <NUM> seconds. The resulting coated support is dried in an oven at <NUM> for <NUM> minutes, and soaked in IPA for <NUM> hours, dried in an oven for <NUM> minutes at <NUM>, and surface tension and weight gain were measured. The weight gain and surface tension results obtained are set forth in Tables <NUM>-<NUM>.

This example illustrates the preparation of a block copolymer of perfluorohexyl ethyl thiol and chloromethyl styrene (poly(pfotms-b-cms)), in accordance with an embodiment of the invention.

Poly(pfotms-block-cms) was synthesized by sequential polymerization of chloromethyl styrene and then perfluorohexyl ethyl thiomethyl styrene which was added after <NUM>. A solution of chloromethyl styrene (<NUM>, <NUM> mmol in <NUM> chlorobenzene), recrystallized benzyl peroxide (BPO) (<NUM>, <NUM> mmol) and TEMPO (<NUM>, <NUM>. 3mmol) was charged into a round-bottomed flask. After being degassed in an ice water bath for <NUM>, the reaction mixture was heated at <NUM> for <NUM> to decompose BPO completely, and at <NUM> for <NUM> to allow the polymerization to proceed. The reaction mixture was cooled to room temperature, diluted with <NUM> chlorobenzene, and pfotms (<NUM>, <NUM> mmol in <NUM> chlorobenzene) was added. The mixture was degassed as before. The reaction was carried out at <NUM> for <NUM>. The block copolymer was obtained after dilution with chloroform (<NUM>), precipitation from methanol, and drying to yield <NUM>% from monomer. NMR result showed a cms/pfotms ratio of <NUM>/<NUM>. DSC results indicated that the block copolymer had two Tgs (<NUM> and <NUM>). <NUM>H NMR spectrum of the block copolymer confirmed the structure of the copolymer. Table <NUM> shows some of the properties, e.g., Tg, of the block copolymer.

A block copolymer of p-[[(perfluorooctyl)ethylene]thiomethyl]- styrene and chloromethyl styrene (poly(pfdtms-b-cms)) was also synthesized using the same procedure.

This example illustrates a method of preparing a porous membrane from a copolymer in accordance with an embodiment of the invention.

p-[[(perfluorooctyl)ethylene]thiomethyl]-styrene and chloromethyl styrene (Poly(pfdtms-ran-cms)) and polyvinyl chloride/acrylonitrile (PVC-AN) were blended as follows. Poly(pfdtms-ran-cms) and PVC-AN are mixed in THF and stirred at <NUM> rpm for <NUM>. NaHCO<NUM> particles having an average particle size of <NUM> were added to the solution and stirred at <NUM> rpm for <NUM>. The polymer blend was then cast onto a glass plate coated with PEG <NUM>. Alternatively, the polymer blend was cast onto a PET substrate mounted on a glass plate. After slow evaporation of THF at room temperature, the resulting membrane was soaked and etched in a dilute HCl solution over night to remove particles and dried at <NUM> °C oven for <NUM>.

The resulting membrane was charge-modified by treatment with EDTA, iminodisuccinic acid (IDSA), triethylamine (TEA) or iminodiacetic acid (IDA). Table <NUM> sets forth charge density values of the porous membrane modified by IDA, EDTA, and TEA.

This example illustrates a method of removing trace metal ions from microelectronics fluids, particularly water and isopropanol, using the EDTA or IDA modified membranes of Example <NUM>.

Claim 1:
A copolymer comprising polymerized monomeric units I and II, wherein:
monomeric unit I is of the formula A-X-CH<NUM>-B, wherein A is Rf-(CH<NUM>)n, Rf is a perfluoro alkyl group of the formula CF<NUM>-(CF<NUM>)x-, wherein x is <NUM> to <NUM>, n is <NUM> to <NUM>, X is S, and B is vinylphenyl,
monomeric unit II originates from haloalkyl styrene, and
wherein one or more of the halo group(s) of the haloalkyl has/have been replaced with a substituent selected from the group consisting of alkoxy, alkylcarbonyl, hydroxyalkyl, an acidic group, a basic group, a cation, an anion, a zwitterion, hydroxyl, acyloxy, alkylthio, aldehydo, amido, carbamoyl, ureido, cyano, nitro, ethylenediamine tetra acetic acid, iminodiacetic acid, and iminodisuccinic acid.