# US 10,369,725 B2 · Method for preparing free-standing polymer film with micropores

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- Number: US 10,369,725 B2
- Document ID: US10369725B2
- Status: Granted
- Kind: B2
- Application number: 14/959,344
- Filed: 2015-12-04
- Published: 2016-11-24
- Granted: 2019-08-06
- Earliest claimed: 2015-05-21
- Assignees: The Industry & Academic Cooperation in Chungnam National University (IAC)
- Applicants: The Industry & Academic Cooperation in Chungnam National University (IAC)
- Inventors: Ho-Suk Choi; Van Tien Bui
- Web page: https://patentgrep.com/patent/US10369725B2

## CPC

- B29C 39/026: {characterised by the shape of the surface}
- B01D 67/0013: {Casting processes}
- B01D 67/0034: {by micromachining techniques, e.g. using masking and etching steps, photolithography}
- B01D 69/02: characterised by their properties
- B29C 39/36: Removing moulded articles
- B29C 41/12: Spreading-out the material on a substrate {, e.g. on the surface of a liquid}
- B29C 41/22: Making multilayered or multicoloured articles
- B29D 7/01: Films or sheets
- C08J 5/18: Manufacture of films or sheets
- B01D 2323/08: Specific temperatures applied
- B01D 2325/04: Characteristic thickness
- B29K 2033/12: {Polymers of methacrylic acid esters, e.g. PMMA, i.e. polymethylmethacrylate}
- B29K 2105/04: cellular or porous
- B29K 2105/256: {Sheets, plates, blanks or films}
- B29K 2995/0093: hydrophobic
- C08J 2325/06: Polystyrene
- C08J 2333/12: Homopolymers or copolymers of methyl methacrylate
- B29C: SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING (making preforms B29B11/00; making laminated products by combining previously unconnected layers which become one product whose layers will remain together B32B37/00 - B32B41/00)
- 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)
- B29D: PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE (making granules B29B9/00; making preforms B29B11/00)
- C08J: WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H (working, e.g. shaping, of plastics B29)
- B29K: INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR {MOULDS, } REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS

## Abstract

The present invention relates to a method for preparing a free-standing polymer film with micropores in a simple and economical way, and particularly to a method for preparing a free-standing polymer film with micropores that includes: (a) forming a thin film of a water-soluble polymer on a substrate; (b) forming a thin film of a hydrophobic polymer on the water-soluble polymer thin film; (c) treating the substrate having the polymer thin films formed on with a mixed solution of a solvent and a C1-C3 alcohol and drying the substrate; and (d) immersing the dried substrate in water to dissolve the water-soluble polymer thin film and thereby to peel the hydrophobic polymer thin film from the substrate.

## Claims

### Claim 1

A method for preparing a free-standing polymer film with through pores, comprising:
(a) forming a thin film of a water-soluble polymer on a substrate;
(b) applying, on the water soluble polymer thin film, a hydrophobic polymer solution prepared by dissolving a hydrophobic polymer in a single pure solvent to form a non-porous thin film of a hydrophobic polymer on the water-soluble polymer thin film;
(c) applying, on the hydrophobic polymer thin film, a mixed solvent that contains a solvent and a non-solvent,
wherein the non-solvent is a C1-C3 alcohol and the content of the C1-C3 alcohol in the mixed solvent is 5 to 20 vol. %,
and drying the resulting substrate at a relative humidity of 20 to 90%, thereby generating honeycomb-patterned through-pores in the non-porous thin film of the hydrophobic polymer; and
(d) immersing the dried substrate in water to dissolve the water-soluble polymer thin film, thereby enabling the hydrophobic polymer thin film having a honeycomb-patterned through-pore structure to be peeled from the substrate.

### Claim 2 (depends on 1)

The method as claimed in claim 1, wherein the water-soluble polymer has a water solubility of at least 5 wt. %.

### Claim 3 (depends on 1)

The method as claimed in claim 1, wherein the water-soluble polymer comprises polysulfonic acid (PSS), polylactic acid (PLA), polyacrylic acid (PAA), polycarbonic acid (PCA), polyvinyl alcohol (PVA), or any combination thereof.

### Claim 4 (depends on 1)

The method as claimed in claim 1, wherein the hydrophobic polymer comprises polystyrene (PS), polypropylene (PP), polyethylene (PE), polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), polyvinyl chloride (PVC), polycarbonate (PC), polyvinylidene fluoride (PVDF), or any combination thereof.

### Claim 5 (depends on 1)

The method as claimed in claim 1, wherein the single pure solvent comprises methylene chloride, chloroform, chloroethane, pentane, hexane, heptane, methyl acetate, ethyl acetate, tetrahydrofuran, ethyl ether, toluene, or any combination thereof.

### Claim 6 (depends on 1)

The method as claimed in claim 1, wherein the surface pore structure of the free-standing polymer film is controlled by controlling the thickness of the hydrophobic polymer thin film.

### Claim 7 (depends on 1)

The method as claimed in claim 1, wherein the drying process of the step (c) is performed at a temperature of 0 to 50° C.

### Claim 8 (depends on 7)

The method as claimed in claim 7, wherein the water-soluble polymer has a water solubility of at least 5 wt. %.

### Claim 9 (depends on 1)

The method as claimed in claim 1, wherein the solvent of the mixed solvent of the step (c) comprises methylene chloride, chloroform, chloroethane, pentane, hexane, heptane, methyl acetate, ethyl acetate, tetrahydrofuran, ethyl ether, toluene, or any combination thereof.