Self-supporting highly moisture-permeable heat-insulating aerogel film and preparation method thereof

Patent metadata

Field	Value
Publication number	US-11285442-B2
Application number	US-201816638468-A
Country	US
Kind code	B2
Filing date	Apr 23, 2018
Priority date	Jul 31, 2017
Publication date	Mar 29, 2022
Grant date	Mar 29, 2022

Abstract

The invention relates to a self-supporting highly moisture-permeable heat-insulating aerogel film and a preparation method thereof. The aerogel film is a self-supporting single-layer film with a SiO2 porous skeleton structure, having a thickness of 150 μm to 300 μm, which increases an exchange rate of vapor by 50% to 200%, and reduces a heat conductivity coefficient by 50% to 90%. The preparation method includes the following steps: (1) preparation of a template; (2) hydrolysis of nano-cellulose; (3) preparation of an aerogel film; and (4) post-treatment of the aerogel film.

First claim

What is claimed is:

1. A preparation method of a self-supporting highly moisture-permeable heat-insulating aerogel film, comprising the following steps:
(1) washing a glass substrate to remove oil stains on a surface; filtering a solution of a high-molecular polymer through a microporous filter paper and then coating a filtered solution on the glass substrate to obtain a template for later use;
(2) uniformly dispersing nano-cellulose whiskers in an organic solvent under heating and stirring, and then adding a silicon source, an acid and deionized water for hydrolysis;
(3) after the hydrolysis, standing a first mixture, adding a gel solution for gelling, coating an obtained gel on one side of the template having the high-molecular polymer to form an aerogel film and rapidly soaking the aerogel film in a solvent, and then taking out the aerogel film to obtain a template loaded with the aerogel film; and
(4) subjecting the template loaded with the aerogel film to solvent exchange and surface modification, drying, obtaining the aerogel film by stripping the aerogel film from the glass substrate, and then calcining the aerogel film at high temperature to obtain the self-supporting highly moisture-permeable heat-insulating aerogel film.

2. The preparation method of the self-supporting highly moisture-permeable heat-insulating aerogel film according to claim 1 , wherein in the step (1), the washing is to soak the glass substrate in ethanol, acetone and deionized water in sequence for respective ultrasound treatment for 20 minutes to 40 minutes; the high-molecular polymer comprises a terpolymer of acrylamide/2-acrylamido-2-methylpropane sulfonic acid; the solution of the high-molecular polymer has a mass concentration of 10 wt. % to 20 wt. %; and the microporous filter paper has a pore size of 30 μm to 50 μm.

3. A self-supporting highly moisture-permeable heat-insulating aerogel film prepared by the preparation method according to claim 2 , wherein the self-supporting highly moisture-permeable heat-insulating aerogel film is a self-supporting single-layer film with a SiO 2 porous skeleton structure, which has a heat conductivity coefficient of 0.02 W/(mK) to 0.03 W/(mK), has a thickness of 150 μm to 300 μm, and comprises two film types of a flat film and a hollow fiber film; the SiO 2 porous skeleton structure is a three-dimensional network structure; and the hollow fiber film is formed by rolling the flat film.

4. The preparation method of the self-supporting highly moisture-permeable heat-insulating aerogel film according to claim 1 , wherein in the step (2), the nano-cellulose whiskers are prepared through the following method:
dissolving cellulose powder in concentrated sulfuric acid under heating and stirring, cooling a second mixture to room temperature, centrifugally washing the second mixture with distilled water to obtain an emulsion suspension without layering; and after dialyzing and separating the obtained emulsion suspension, washing obtained crystals with water and then lyophilizing the crystals to obtain the nano-cellulose whiskers.

5. A self-supporting highly moisture-permeable heat-insulating aerogel film prepared by the preparation method according to claim 4 , wherein the self-supporting highly moisture-permeable heat-insulating aerogel film is a self-supporting single-layer film with a SiO 2 porous skeleton structure, which has a heat conductivity coefficient of 0.02 W/(mK) to 0.03 W/(mK), has a thickness of 150 μm to 300 μm, and comprises two film types of a flat film and a hollow fiber film; the SiO 2 porous skeleton structure is a three-dimensional network structure; and the hollow fiber film is formed by rolling the flat film.

6. The preparation method of the self-supporting highly moisture-permeable heat-insulating aerogel film according to claim 4 , wherein the heating and stirring is to stir at 60° C. to 80° C.; the concentrated sulfuric acid has a concentration of 50 wt. % to 70 wt. %; the cooling to room temperature is to directly add distilled water for cooling; the dialyzing is to put the emulsion suspension obtained by centrifugation into a cellulose dialysis bag and then put the cellulose dialysis bag into deionized water for dialysis until a pH value of a dialysate reaches 7.0; and the lyophilizing is to lyophilize at −50° C. to −30° C.

7. A self-supporting highly moisture-permeable heat-insulating aerogel film prepared by the preparation method according to claim 6 , wherein the self-supporting highly moisture-permeable heat-insulating aerogel film is a self-supporting single-layer film with a SiO 2 porous skeleton structure, which has a heat conductivity coefficient of 0.02 W/(mK) to 0.03 W/(mK), has a thickness of 150 μm to 300 μm, and comprises two film types of a flat film and a hollow fiber film; the SiO 2 porous skeleton structure is a three-dimensional network structure; and the hollow fiber film is formed by rolling the flat film.

8. The preparation method of the self-supporting highly moisture-permeable heat-insulating aerogel film according to claim 1 , wherein in the step (2), the silicon source comprises one of tetramethyl orthosilicate, tetraethyl orthosilicate, methyltrimethoxysilane, water glass, trimethylethoxysilane and silsesquioxane; and different organic solvents are added according to different silicon sources: when the silicon source is tetramethyl orthosilicate, the organic solvent is dimethyl sulfoxide; when the silicon source is tetraethyl orthosilicate, the organic solvent is ethanol; when the silicon source is methyltrimethoxysilane, the organic solvent is tetrahydrofuran; when the silicon source is sodium silicate, the organic solvent is toluene; and when the silicon source is trimethylethoxysilane or silsesquioxane, the organic solvent is dimethylacetamide.

9. A self-supporting highly moisture-permeable heat-insulating aerogel film prepared by the preparation method according to claim 8 , wherein the self-supporting highly moisture-permeable heat-insulating aerogel film is a self-supporting single-layer film with a SiO 2 porous skeleton structure, which has a heat conductivity coefficient of 0.02 W/(mK) to 0.03 W/(mK), has a thickness of 150 μm to 300 μm, and comprises two film types of a flat film and a hollow fiber film; the SiO 2 porous skeleton structure is a three-dimensional network structure; and the hollow fiber film is formed by rolling the flat film.

10. The preparation method of the self-supporting highly moisture-permeable heat-insulating aerogel film according to claim 1 , wherein in the step (2), a solid-liquid ratio of the nano-cellulose whiskers to the organic solvent is 5-10: 80-100 g/ml; a mass ratio of the organic solvent to the silicon source is 0.8-1.5:0.3-0.6; a volume ratio of the organic solvent to the deionized water is 30-50: 2-4; and an addition amount of the acid is added according to a molar ratio of hydrogen atoms in the acid to silicon atoms in the silicon source of 10 −5 -10 −3 : 1-3, wherein a pH value of the solution after the acid is added is 5-6.

11. A self-supporting highly moisture-permeable heat-insulating aerogel film prepared by the preparation method according to claim 10 , wherein the self-supporting highly moisture-permeable heat-insulating aerogel film is a self-supporting single-layer film with a SiO 2 porous skeleton structure, which has a heat conductivity coefficient of 0.02 W/(mK) to 0.03 W/(mK), has a thickness of 150 μm to 300 μm, and comprises two film types of a flat film and a hollow fiber film; the SiO 2 porous skeleton structure is a three-dimensional network structure; and the hollow fiber film is formed by rolling the flat film.

12. The preparation method of the self-support

Assignees

• Univ South China Tech

Inventors

• Zhang Lizhi
• Su Qianwen

Classifications

• B01D67/0009 Primary

  by phase separation, sol-gel transition, evaporation or solvent quenching · CPC title

• B01D71/702

  Polysilsesquioxanes or combination of silica with bridging organosilane groups · CPC title

• B01D2325/24

  Mechanical properties, e.g. strength · CPC title

• B01D69/02

  characterised by their properties · CPC title

• B01D53/268

  by diffusion · CPC title