# US 11,110,400 B2 · Porous polyelectrolyte complex films and foams and related methods > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,110,400 B2 - Document ID: US11110400B2 - Status: Granted - Kind: B2 - Application number: 16/611,347 - Filed: 2018-05-09 - Published: 2020-05-28 - Granted: 2021-09-07 - Earliest claimed: 2017-05-10 - Assignees: Northwestern University - Applicants: Northwestern University - Inventors: Kenneth R. Shull; Kazi Sadman; Qifeng Wang - Web page: https://patentgrep.com/patent/US11110400B2 ## CPC - B01D 67/0013: {Casting processes} - B01D 67/00111: {Polymer pretreatment in the casting solutions} - B01D 67/0023: {by inducing porosity into non porous precursor membranes} - B01D 69/02: characterised by their properties - B01D 71/281: {Polystyrene} - B01D 71/283: {Polyvinylpyridine} - B05D 1/28: performed by transfer from the surfaces of elements carrying the liquid or other fluent material, e.g. brushes, pads, rollers - B05D 1/36: Successively applying liquids or other fluent materials, e.g. without intermediate treatment - B32B 27/00: Layered products comprising {a layer of} synthetic resin {(fibrous or filamentary layer made of a synthetic resin B32B5/02; particulate layer made of a synthetic resin B32B5/16; foamed layer made of a synthetic resin B32B5/18)} - B01D 61/02: Reverse osmosis; Hyperfiltration {; Nanofiltration} - B01D 61/027: {Nanofiltration} - B01D 61/14: Ultrafiltration; Microfiltration - B01D 61/145: {Ultrafiltration} - B01D 61/147: {Microfiltration} - B01D 2323/219: Specific solvent system - B01D 2325/0283: Pore size - B01D 2325/18: Membrane materials having mixed charged functional groups - B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28) - B05D: PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL (conveying articles or workpieces through baths of liquid B65G, e.g. B65G49/02) - B32B: LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM ## Abstract Methods for making porous polyelectrolyte complex (PEC) films are provided. In an embodiment, such a method comprises coating the surface of a substrate with a polyelectrolyte (PE) coacervate mixture, the PE coacervate mixture comprising a cationic polymer, an anionic polymer, water, and a salt, the PE coacervate having a salt concentration; exposing the coating to an aqueous medium having another salt concentration, for a time to induce solidification of polyelectrolyte complexes (PECs) in the form of a PEC film having pores distributed throughout, wherein a difference Δ?C-M #191 between the salt concentration of the PE coacervate mixture and the salt concentration of the aqueous medium is selected to achieve a predetermined porosity for the porous PEC film. ## Claims ### Claim 1 A method for making a porous polyelectrolyte complex (PEC) film having a predetermined porosity, the method comprising: coating the surface of a substrate with a polyelectrolyte (PE) coacervate mixture, the PE coacervate mixture comprising a cationic polymer, an anionic polymer, water, and a salt, the PE coacervate mixture having a salt concentration; exposing the coating to an aqueous medium having another salt concentration, for a time to remove sufficient salt from the coating to induce solidification of polyelectrolyte complexes (PECs) in the form of a PEC film having pores distributed throughout, wherein the pores have an average diameter in the range of from about 300 nm to about 3 μm, wherein a difference ΔC-M between the salt concentration of the PE coacervate mixture and the salt concentration of the aqueous medium is selected to achieve a predetermined porosity for the porous PEC film. ### Claim 2 (depends on 1) The method of claim 1, determining the difference ΔC-M from a calibration plot of ΔC-M versus porosity. ### Claim 3 (depends on 1) The method of claim 1, wherein the time of exposure to the aqueous medium is at least 30 minutes. ### Claim 4 (depends on 1) The method of claim 1, wherein the coating step is carried out using blade casting or roll casting. ### Claim 5 (depends on 1) The method of claim 1, further comprising removing water from the porous PEC film. ### Claim 6 (depends on 5) The method of claim 5, wherein the water removal is carried out via an air gun. ### Claim 7 (depends on 1) The method of claim 1, further comprising exposing the porous PEC film to an aqueous salt solution having an ionic strength sufficient to dissolve the PECs. ### Claim 8 (depends on 7) The method of claim 7, further comprising regenerating the porous PEC film from the dissolved PECs. ### Claim 9 (depends on 1) The method of claim 1, wherein the cationic polymer is selected from a group consisting of poly(allylamine), poly(ethyleneimine), Chitosan, poly(N-alkyl 4-vinyl pyridinium), poly(N-alkyl 2-vinyl pyridinium), poly(diallyldimethylammonium), poly([2-(Acryloyloxy)ethyl]trimethylammonium), Poly(N,N-dimethyl-3,5-dimethylene piperidinium chloride), poly(vinylbenzyltrimethylammonium chloride), polyvinylamine and combinations thereof, and the anionic polymer is selected from poly(acrylic acid), poly(methacrylic) acid, Agar, Alginate, Hyaluronic Acid, poly(styrene sulfonate), poly(phosphate) poly(vinylsulfonic acid), poly(acrylamido-2-methylpropanesulfonate), and combinations thereof. ### Claim 10 (depends on 9) The method of claim 9, wherein the salt is selected from a group consisting of potassium bromide, sodium chloride, potassium chloride, sodium bromide, sodium thiocyanate, guanidinium bromide, guanidinium thiocyanate, and combinations thereof. ### Claim 11 (depends on 1) The method of claim 1, wherein the predetermined porosity is in the range of from 10% to 90%. ### Claim 12 (depends on 11) The method of claim 11, wherein the predetermined porosity is in the range of from 10% to 60%. ### Claim 13 (depends on 1) The method of claim 1, wherein the pores comprise interconnected pores and closed pores. ### Claim 14 (depends on 13) The method of claim 13, wherein the interconnected pores are in the form of elongated, tortuous channels extending in three-dimensions. ### Claim 15 A method for making a porous polyelectrolyte complex (PEC) film having a predetermined porosity, the method comprising: coating the surface of a substrate with a polyelectrolyte (PE) coacervate mixture, the PE coacervate mixture comprising a cationic polymer, an anionic polymer, water, and a salt, the PE coacervate mixture having a salt concentration; exposing the coating to an aqueous medium having another salt concentration, for a time to induce solidification of polyelectrolyte complexes (PECs) in the form of a PEC film having pores distributed throughout, wherein a difference ΔC-M between the salt concentration of the PE coacervate mixture and the salt concentration of the aqueous medium is selected to achieve a predetermined porosity for the porous PEC film, wherein the porous PEC film is composed of a first sublayer and a second sublayer overlying the first sublayer and at the surface of the porous PEC film, wherein the first and second sublayers are characterized by different average pore diameters. ### Claim 16 (depends on 15) The method of claim 15, wherein the average pore diameter of the second sublayer is smaller than the average pore diameter of the first sublayer. ### Claim 17 A method for making a porous polyelectrolyte complex (PEC) film having a predetermined porosity, the method comprising: coating the surface of a substrate with a polyelectrolyte (PE) coacervate mixture, the PE coacervate mixture comprising a cationic polymer, an anionic polymer, water, and a salt, the PE coacervate mixture having a salt concentration; exposing the coating to an aqueous medium having another salt concentration, for a time to induce solidification of polyelectrolyte complexes (PECs) in the form of a PEC film having pores distributed throughout, wherein a difference ΔC-M between the salt concentration of the PE coacervate mixture and the salt concentration of the aqueous medium is selected to achieve a predetermined porosity for the porous PEC film, wherein the PE coacervate mixture further comprises a foaming agent and the method further comprises inducing the foaming agent to undergo a reaction to release a gas, thereby generating bubbles throughout the PE coacervate mixture, prior to the exposing step. ### Claim 18 (depends on 1) The method of claim 1, wherein the porous PEC film is characterized as having the ability to reject at least 90% of polystyrene beads having a diameter of at least 100 nm. ### Claim 19 (depends on 1) The method of claim 1, wherein the porous PEC film characterized as having the ability to reject at least 90% of PEGs having a molecular weight of at least 104 g/mol.