Method for producing porous thin film with variable transmittance

• US 8,765,229 B2
• Filed: 11/12/2012
• Issued: 07/01/2014
• Est. Priority Date: 08/30/2012
• Status: Active Grant

• Current Assignee: National Tsing Hua University
• Original Assignee: National Tsing Hua University
• Inventors: Hsu, Wen-Kuang, Chen, Ying-Tzu
• Primary Examiner(s): CAMERON, ERMA C
• Application Number:
  US13/674,462
• Publication Number:
  US 20140065314A1
• Time in Patent Office: 596 Days
• Field of Search: None
• US Class Current: 427/389.7
• CPC Class Codes: B05D 1/00 Processes for applying liquids or other fluent materials B05D5/00, B05D7/00 take precedence
• CPC Class Codes: B05D 2203/35 Glass
• CPC Class Codes: B05D 2301/00 Inorganic additives or organic salts thereof
• CPC Class Codes: B05D 2401/10 Organic solvent B05D2401/21 takes precedence
• CPC Class Codes: B05D 3/0486 Operating the coating or treatment in a controlled atmosphere
• CPC Class Codes: B05D 3/0493 using vacuum
• CPC Class Codes: B05D 3/12 by mechanical means
• CPC Class Codes: B05D 5/065 having colour interferences or colour shifts or opalescent looking, flip-flop, two tones
• CPC Class Codes: C08K 3/16 Halogen-containing compounds
• CPC Class Codes: C08L 2203/16 used for films
• CPC Class Codes: C08L 35/04 Homopolymers or copolymers of nitriles C08L35/06, C08L35/08 take precedence
• CPC Class Codes: C09D 133/18 Homopolymers or copolymers of nitriles
• CPC Class Codes: C09D 133/20 Homopolymers or copolymers of acrylonitrile C09D155/02 takes precedence

Abstract

A method for producing a porous thin film with variable transmittance, includes placing a polymer into an oven for an drying process to remove water vapor from the polymer and obtain a dry polymer; mixing the dry polymer, a salt and a solvent in accordance with a mixing ratio so as to obtain a first mixed solution; placing the first mixed solution into an ultrasonic vibrator, dissolving the salt to form a second mixed solution; coating the second mixed solution on a glass plate to form a solution thin film; placing solution thin film into an exhaust cabinet to obtain a composite thin film; and washing the composite thin film to remove the salt from the composite thin film to obtain a porous thin film wherein the polymer is a polyacrylonitrile, the salt is a lithium chloride, the porous thin film changes its transmittance via dry and wet state.

Claims

1. A method for producing a porous thin film with adjustable light transmittance, comprising steps of:

removing water from a polymer to obtain a dry polymer;

mixing the dry polymer with a salt and a solvent to obtain a first solution;

wherein the salt is lithium chloride with 30-50 wt % weight ratio of the salt over the polymer;

completely dissolving the salt from the first solution by ultra sonic to form a second solution;

coating the second solution on a glass plate to form a solution thin film;

obtaining a composite thin film by placing the solution thin film into an exhaust cabinet;

washing out the salt from the composite thin film to obtain a porous thin film; and

adjusting a light transmittance the porous thin film by wetting or drying the porous thin film.

2. The method for producing a porous thin film with adjustable light transmittance as claimed in claim 1, wherein the polymer is a polyacrylonitrile.

3. The method for producing a porous thin film with adjustable light transmittance as claimed in claim 1, wherein the solvent includes a dimethyl formamide and a dimethyl-acetylated amine.

4. The method for producing a porous thin film with adjustable light transmittance as claimed in claim 1, wherein the coating step is proceeded under an environment of a relative humidity ranging from 10 to 95%.

5. The method for producing a porous thin film with adjustable light transmittance as claimed in claim 3, wherein the solvent further comprises dimethyl sulfoxide, toluene, or acetone.

6. The method for producing a porous thin film with adjustable light transmittance as claimed in claim 1, wherein the porous thin film has different spectral transmittance between dry and water-saturated state.

7. The method for producing a porous thin film with adjustable light transmittance as claimed in claim 1, wherein the polymer is one selected from the following group consisting of:

polytetrafluoroethylene, hydrophilic thermoplastic polyurethanes, polyamides, and Polyethylene terephthalate.

8. A method for producing a porous thin film with adjustable light transmittance, comprising steps of:

removing water from a polymer to obtain a dry polymer;

mixing the dry polymer with a salt and a solvent to obtain a first solution, wherein the salt is lithium chloride with 30-50 wt % weight ratio of the salt over the polymer, and the solvent is a mixture of dimethyl formamide and dimethyl-acetylated amine in 1;

1 volume ratio;

completely dissolving the salt from the first solution by ultra sonic to form a second solution;

coating the second solution on a glass plate to form a solution thin film;

obtaining a composite thin film by placing the solution thin film into an exhaust cabinet;

washing out the salt from the composite thin film to obtain a porous thin film; and

adjusting the light transmittance by wetting or drying the porous thin film.