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"Filters for Oil-Water Separation Having Zwitterionic Polymers Coated Or Grafted Thereon" in Patent Application Approval Process

August 19, 2014



By a News Reporter-Staff News Editor at Life Science Weekly -- A patent application by the inventor Liu, Lingyun (Tallmadge, OH), filed on January 31, 2014, was made available online on August 7, 2014, according to news reporting originating from Washington, D.C., by NewsRx correspondents (see also The University Of Akron).

This patent application is assigned to The University Of Akron.

The following quote was obtained by the news editors from the background information supplied by the inventors: "Separation of oil and water has been a worldwide challenge for some time. Oil-water separation is necessary due to increasing environmental awareness and regulations. Also, the production of industrial wastewater and accidental spillage of oil leads to a need for oil-water separation.

"Certain efforts to increase the effectiveness of oil-water separation have involved the creation of devices that have hydrophobic-oleophilic (i.e. oil-removing) surfaces or hydrophilic-oleophobic (i.e. water-removing) surfaces. However, oil-removing surfaces tend to foul easily and become blocked by oils. These oils adhere to the surfaces and are hard to remove. This greatly affects the separation efficiency.

"Substrates that have been previously studied for oil-water separation include polymers, such as polytetrafluoroethylene (PTFE), polyethylene, and polyurethane; metals, such as stainless steel and copper; ceramics, such as glass and manganese oxide; and others, such as filter paper, textile, and silicon. These have been in the form of fibers, meshes, foams, or surfaces. Certain embodiments of these substrates offer inferior properties, such as low flexibility and poor mechanical stability. Hydrophilic-oleophobic surfaces have been incorporated into certain embodiments of these substrates; however, the resultant substrates have not yet been used for oil-water separation.

"Altering the wettability of a surface also affects the oil-water separation. The wettability of a surface can be changed by using surface modification techniques in order to achieve antifouling surfaces. Such techniques include vapor deposition, dip coating, spray coating, spin coating, and polymer grafting. A surface having superoleophobic properties generally requires the use of a hydrophilic material and hierarchical surface structures. Superoleophobic surfaces generally require the combination of surface chemistry and surface roughness properties.

"The present invention employs zwitterionic species to modify the properties of filter media and provide an improved filter that provides more effective oil-water separation. Embodiments of the present invention offer one or more of the following improved properties: easy production, easy re-use or recycling, high resistance to organic contaminants (such as oil), high separation efficiency, low operating costs, and the use of highly roughed surfaces (e.g., nano-structured surfaces) is not necessary."

In addition to the background information obtained for this patent application, NewsRx journalists also obtained the inventor's summary information for this patent application: "In a first embodiment, the present invention provides a filter for the separation of oil and water from oil-water mixtures comprising a porous filter media, wherein the porous filter media has a zwitterionic polymer grafted or coated thereon.

"In a second embodiment, the present invention provides a filter as in the first embodiment, wherein the zwitterionic polymer is selected according to the following structure:

"##STR00001##

"wherein X is selected from the group consisting of hydrogen or a methyl group; Y is selected from the group consisting of an ester and an amide; n is an integer from 1 to 4, m is an integer from 1 to 5, Z is selected from the group consisting of SO.sub.3 or COO; and R.sub.1, R.sub.2 and R.sub.3 are each any moiety.

"In a third embodiment, the present invention provides a filter as in either the first or second embodiments, wherein the zwitterionic polymer employs the first structure and X is methyl, Y is ester, n is 2, m is 3, and Z is SO.sub.3.

"In a fourth embodiment, the present invention provides a filter as in any of the first through third embodiments, wherein the zwitterionic polymer employs the first structure and X is methyl, Y is ester, n is 2, m is 2, and Z is COO.

"In a fifth embodiment, the present invention provides a filter as in any of the first through fourth embodiments, wherein the zwitterionic polymer employs the first structure and X is hydrogen, Y is amide, n is 2, m is 1, 3, or 5, and Z is COO.

"In a sixth embodiment, the present invention provides a filter as in any of the first through fifth embodiments, wherein the zwitterionic polymer employs the second structure and X is methyl, Y is ester, n is 2, m is 2 and R.sub.1, R.sub.2 and R.sub.3 are each a methyl group.

"In a seventh embodiment, the present invention provides a filter as in any of the first through sixth embodiments, wherein the porous filter media comprises glass fibers.

"In an eighth embodiment, the present invention provides a filter as in any of the first through seventh embodiments, wherein the zwitterionic polymer is selected from the group consisting of poly(carboxybetaine methacrylate) (pCBMA), poly(sulfobetaine methacrylate) (pSBMA), poly(2-methacryloyloxyethyl phosphorylcholine) (pMPC), poly(serine methacrylate), and polyampholyte mixed-charge copolymers.

"In a ninth embodiment, the present invention provides a filter as in any of the first through eighth embodiments, wherein the zwitterionic polymer is a polyampholyte mixed-charge copolymer comprising a positively charged monomer selected from the group consisting of quaternary amine monomers and protonated primary amine monomers, wherein the quaternary amine monomer, if present, is selected from the group consisting of [2-(acryloyloxy)ethyl]trimethyl ammonium chloride and [2-(methacryloyloxy)ethyl]trimethyl ammonium chloride; and a negatively charged acrylate monomer selected from the group consisting of 2-carboxy ethyl acrylate and 3-sulfopropyl methacrylate potassium salt.

"In a tenth embodiment, the present invention provides a filter as in any of the first through ninth embodiments, wherein the zwitterionic polymer is made from a monomer selected from the group consisting of N-.epsilon.-methacryloyl lysine, N-.delta.-methacryloyl ornithine, N.sup.4-(2-methacrylamidoethyl) asparagine, and N.sup.5-(2-methacrylamidoethyl) glutamine.

"In an eleventh embodiment, the present invention provides a filter as in any of the first through tenth embodiments, wherein the filter has a water contact angle of approximately 8-15.degree. and an underwater oil contact angle of approximately 162-169.degree.

"In a twelfth embodiment, the present invention provides a method of forming a filter comprising the steps of providing a porous filter media; providing a zwitterionic polymer; and coating or grafting a zwitterionic polymer onto a surface of the filter media.

"In a thirteenth embodiment, the present invention provides a method as in the twelfth embodiment, wherein the substrate comprises glass fibers.

"In a fourteenth embodiment, the present invention provides a method as in either the twelfth or thirteenth embodiments, wherein the zwitterionic polymer is selected from the group consisting of poly(carboxybetaine methacrylate) (pCBMA), poly(sulfobetaine methacrylate) (pSBMA), poly(2-methacryloyloxyethyl phosphorylcholine) (pMPC), poly(serine methacrylate), and polyampholyte mixed-charge copolymers.

"In a fifteenth embodiment, the present invention provides a method as in any of the twelfth through fourteenth embodiments, wherein said step of coating or grafting is a step of grafting, and the method further comprises securing an anchor initiator to the surface of the filter media and said step of grafting includes initiating polymerization of monomers with the anchor initiator to form the zwitterionic polymer.

"In a sixteenth embodiment, the present invention provides a method as in any of the twelfth through fifteenth embodiments, wherein the anchor initiator is an atom transfer radical polymerization initiator and the zwitterionic polymer is grafted using atom transfer radical polymerization of the monomers.

"In a seventeenth embodiment, the present invention provides a method as in any of the twelfth through sixteenth embodiments, wherein the monomers polymerized in said step of grafting are selected from: zwitterionic monomers, forming zwitterionic polymers having positive and negative charges in series on the same side chain; a mixture of cationic and anionic monomers, forming zwitterionic polymers having positive and negative charges on two different side chains; and monomers with cationic-anionic pairs, forming zwitterionic polymers having positive and negative charges in parallel on the same side chain.

"In an eighteenth embodiment, the present invention provides a method as in any of the twelfth through seventeenth embodiments, wherein the monomers are a mixture of cationic and anionic monomer, the cationic monomer selected from the group consisting of quaternary amine monomers and protonated primary amine monomers, wherein the quaternary amine monomer, if employed, is selected from the group consisting of [2-(acryloyloxy)ethyl]trimethyl ammonium chloride and [2-(methacryloyloxy)ethyl]trimethyl ammonium chloride, and the anionic monomer is an acrylate monomer selected from the group consisting of 2-carboxy ethyl acrylate and 3-sulfopropyl methacrylate potassium salt.

"In a nineteenth embodiment, the present invention provides a method as in any of the twelfth through eighteenth embodiments, wherein the monomers are monomers with cationic-anionic pairs selected from the group consisting of N-.epsilon.-methacryloyl lysine, N-.delta.-methacryloyl ornithine, N.sup.4-(2-methacrylamidoethyl) asparagine, and N.sup.5-(2-methacrylamidoethyl) glutamine.

"In a twentieth embodiment, the present invention provides a method as in any of the twelfth through nineteenth embodiments, wherein the coating or grafting step is a step of coating.

"In a twenty-first embodiment, the present invention provides a method as in any of the twelfth through twentieth embodiments, wherein the zwitterionic polymer in said step of coating is selected from: zwitterionic polymers formed from zwitterionic monomers, the zwitterionic polymers having positive and negative charges in series on the same side chain; zwitterionic polymers formed from a mixture of cationic and anionic monomers, the zwitterionic polymers having positive and negative charges on two different side chains; and zwitterionic polymers formed from monomers with cationic-anionic pairs, the zwitterionic polymers having positive and negative charges in parallel on the same side chain.

"In a twenty-second embodiment, the present invention provides a method as in any of the twelfth through twenty-first embodiments, wherein the zwitterionic polymer is a zwitterionic polymer formed from mixtures of cationic and anionic monomer, the cationic monomer selected from the group consisting of quaternary amine monomers and protonated primary amine monomers, wherein the quaternary amine monomer, if employed, is selected from the group consisting of [2-(acryloyloxy)ethyl]trimethyl ammonium chloride and [2-(methacryloyloxy)ethyl]trimethyl ammonium chloride, and the anionic monomer is an acrylate monomer selected from the group consisting of 2-carboxy ethyl acrylate and 3-sulfopropyl methacrylate potassium salt.

"In a twenty-third embodiment, the present invention provides a method as in any of the twelfth through twenty-second embodiments, wherein the zwitterionic polymer is a zwitterionic polymer formed from monomers with cationic-anionic pairs, the monomers with cationic-anionic pairs being selected from the group consisting of N-.epsilon.-methacryloyl lysine, N-.delta.-methacryloyl ornithine, N.sup.4-(2-methacrylamidoethyl) asparagine, and N.sup.5-(2-methacrylamidoethyl) glutamine.

"In a twenty-fourth embodiment, the present invention provides a method of using a filter for the separation of oil and water from oil-water mixtures comprising the steps of: providing a mixture or emulsion comprising oil and water; providing a porous filter media; coating or grafting a zwitterionic polymer onto the porous filter media; allowing the oil and water mixture or emulsion to contact the porous filter media, whereby the porous filter media allows the water to pass through.

"In a twenty-fifth embodiment, the present invention provides a method as in the twenty-fourth embodiment, wherein the filter substrate comprises glass fibers.

"In a twenty-sixth embodiment, the present invention provides a method as in either the twenty-fourth or twenty-fifth embodiments, wherein the zwitterionic polymer is selected from the group consisting of poly(carboxybetaine methacrylate) (pCBMA), poly(sulfobetaine methacrylate) (pSBMA), poly(2-methacryloyloxyethyl phosphorylcholine) (pMPC), poly(serine methacrylate), and polyampholyte mixed-charge copolymers.

"In a twenty-seventh embodiment, the present invention provides a method as in any of the twenty-fourth through twenty-sixth embodiments, wherein the zwitterionic polymer is a polyampholyte mixed-charge copolymer comprising: a positively charged monomer selected from the group consisting of quaternary amine monomers and protonated primary amine monomers, wherein the quaternary amine monomer, if present, is selected from the group consisting of [2-(acryloyloxy)ethyl]trimethyl ammonium chloride and [2-(methacryloyloxy)ethyl]trimethyl ammonium chloride, and a negatively charged acrylate monomer selected from the group consisting of 2-carboxy ethyl acrylate and 3-sulfopropyl methacrylate potassium salt.

"In a twenty-eighth embodiment, the present invention provides a method as in any of the twenty-fourth through twenty-seventh embodiments, wherein the zwitterionic polymer is made from a monomer selected from the group consisting of N-.epsilon.-methacryloyl lysine, N-.delta.-methacryloyl ornithine, N.sup.4-(2-methacrylamidoethyl) asparagine, and N.sup.5-(2-methacrylamidoethyl) glutamine.

BRIEF DESCRIPTION OF THE DRAWINGS

"Advantages of the present invention will become better understood with regard to the following description, appended claims, and accompanying drawings provided herein.

"FIG. 1 is a schematic drawing showing the grafting of pSBMA on a glass surface via surface-initiated atom transfer radical polymerization.

"FIG. 2 is a graph showing PSBMA film thickness measured as a function of polymerization time using ellipsometry.

"FIG. 3a is an image showing the in-air water contact angles at various pSBMA polymerization times.

"FIG. 3b is an image showing the underwater hexadecane contact angles at various pSBMA polymerization times.

"FIG. 4a is a graph showing the in-air water contact angle for pSBMA-grafted glass substrates at various reaction times. The sample with a 0 reaction time refers to the control glass without pSBMA modification.

"FIG. 4b is a graph showing the underwater hexadecane contact angle for pSBMA-grafted glass substrates at various reaction times. The sample with a 0 reaction time refers to the control glass without pSBMA modification.

"FIG. 5a is a graph showing data for oil-water separation of pSBMA-grafted glass fiber filters for various polymerization times. The graph shows the amount of permeated water, permeated oil, and total permeate after 24-hour permeation. Water (10 mL) was first used to hydrate the filters, followed by the addition of a mixed water:hexadecane solution (20 mL:10 mL).

"FIG. 5b is a graph showing data for oil-water separation of pSBMA-grafted glass fiber filters for various polymerization times. The graph shows the amount of permeated oil with increasing permeation time. Water (10 mL) was first used to hydrate the filters, followed by the addition of a mixed water:hexadecane solution (20 mL:10 mL)."

URL and more information on this patent application, see: Liu, Lingyun. Filters for Oil-Water Separation Having Zwitterionic Polymers Coated Or Grafted Thereon. Filed January 31, 2014 and posted August 7, 2014. Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=6138&p=123&f=G&l=50&d=PG01&S1=20140731.PD.&OS=PD/20140731&RS=PD/20140731

Keywords for this news article include: Anions, Lysine, Chemicals, Chemistry, Glutamine, Asparagine, Acyclic Acids, Methacrylates, Ammonium Chloride, Basic Amino Acids, Hydrochloric Acid, Diamino Amino Acids, Neutral Amino Acids, Essential Amino Acids, The University Of Akron, Quaternary Ammonium Compounds.

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Source: Life Science Weekly


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