Cellulose foams for high performance insulations

Patent metadata

Field	Value
Publication number	US-11725091-B2
Application number	US-202016900464-A
Country	US
Kind code	B2
Filing date	Jun 12, 2020
Priority date	Jun 14, 2019
Publication date	Aug 15, 2023
Grant date	Aug 15, 2023

Abstract

Environmentally friendly, sustainable, and high-performance ultralight composite foams are disclosed. The composite foams are prepared from cellulose nanomaterial, polymeric material, and a crosslinking agent. The fabrication process is simple and uses only water. The composite foams exhibit an elastic strain exceeding the values reported for known nanocellulose-based foams with no reinforcement. The foams exhibit a thermal conductivity superior to that of traditional insulating materials and retain structural integrity after burning.

First claim

We claim:

1. A composite foam, comprising:
about 10 wt % to about 95 wt % of a cellulose component wherein said cellulose component is about 20 wt % to about 100 wt % cellulose nanomaterial;
about 1 wt % to about 25 wt % of a water-soluble polymer comprising a plurality of first crosslinkable groups,
about 1 wt % to about 25 wt % of a water-soluble crosslinking agent comprising a plurality of second crosslinkable groups;
wherein at least a portion of the second crosslinkable groups are covalently bonded with at least a portion of the first crosslinkable groups and at least a portion of the hydroxy groups of the cellulose component; and
wherein the composite foam has an apparent density of about 0.01 g/cm 3 to about 0.25 g/cm 3 .

2. The composite foam of claim 1 , wherein the composite foam has a porosity of about 30% to about 99%.

3. The composite foam of claim 1 , wherein the cellulose component comprises 100 wt % cellulose nanomaterial.

4. The composite foam of claim 1 , wherein the first crosslinkable group is a hydroxyl, a thiol, a hydrazide, an amino group, or a combination thereof.

5. The composite foam of claim 1 , wherein the second crosslinkable group is a carboxylic acid, an anhydride, an activated ester, an aldehyde, a ketone, or a combination thereof.

6. The composite foam of claim 1 , wherein water-soluble polymer is polyvinyl alcohol (PVA), polyethylene glycol (PEG), polyacrylic acid (PAA), polyvinyl pyrrolidone (PVP), polyacrylamide (PAM), alginic acid, starch, xanthan gum, dextran, pectin, or a combination thereof.

7. The composite foam of claim 1 , wherein water-soluble crosslinking agent is 1,2,3,4-butane tetracarboxylic acid, oxalic acid, succinic acid, malic acid, citric acid, adipic acid, or a combination thereof.

8. The composite foam of claim 1 , wherein the composite foam is formed by freeze-casting of a precursor composition that does not comprise an organic solvent.

9. The composite foam of claim 1 , wherein the composite foam has a compression stress measured at 50% strain from about 50 kPa to about 250 kPa.

10. The composite foam of claim 1 , wherein the composite foam has thermal conductivity from about 0.015 Wm −1 K −1 to about 0.045 Wm −1 K −1 .

11. The composite foam of claim 1 , wherein the composite foam has an elastic strain of at least 10% at Young's modulus of from 50 kPa to about 1500 kPa.

12. The composite foam of claim 1 , wherein the composite foam comprises a colorant.

13. The composite foam of claim 1 , wherein at least a portion of the hydroxy groups of the cellulose component are silanized.

14. A building product or a consumer product comprising the composite foam of claim 1 .

15. The building product of claim 14 , wherein the building product is an insulation panel.

16. The consumer product of claim 14 , wherein the consumer product is a cup, a plate, a shipping container, a cooler, or a potting container.

17. A method of making a composite foam, comprising freeze-casting or freeze-drying an aqueous composition comprising a foam precursor, wherein the foam precursor comprises:
about 10 wt % to about 95 wt % of a cellulose component wherein said cellulose component is about 20 wt % to about 100 wt % cellulose nanomaterial;
about 1 wt % to about 25 wt % of a water-soluble polymer comprising a plurality of first crosslinkable groups, about 1 wt % to about 25 wt % of a water-soluble crosslinking agent comprising a plurality of second crosslinkable groups;
wherein at least a portion of the second crosslinkable groups can form covalent bonds with at least a portion of the first crosslinkable groups and at least a portion of the hydroxy groups of the cellulose component; and
wherein the composite foam has an apparent density of about 0.01 g/cm 3 to about 0.25 g/cm 3 .

18. The method of claim 17 , wherein the aqueous composition does not include an organic solvent.

19. A composite foam prepared by a method of making a composite foam, comprising freeze-casting or freeze-drying an aqueous composition comprising a foam precursor, wherein the foam precursor comprises:
about 10 wt % to about 95 wt % of a cellulose component wherein said cellulose component is about 20 wt % to about 100 wt % cellulose nanomaterial;
about 1 wt % to about 25 wt % of a water-soluble polymer comprising a plurality of first crosslinkable groups; and
about 1 wt % to about 25 wt % of a water-soluble crosslinking agent comprising a plurality of second crosslinkable groups;
wherein at least a portion of the second crosslinkable groups can form covalent bonds with at least a portion of the first crosslinkable groups and at least a portion of the hydroxy groups of the cellulose component; and
wherein the composite foam has an apparent density of about 0.01 g/cm 3 to about 0.25 g/cm 3 .

Assignees

• Univ Washington State

Inventors

• Zhang Xiao
• Ameli Aboutaleb
• Wang Peipei

Classifications

• C08J9/125 Primary

  Water, e.g. hydrated salts · CPC title

• C08J2203/10

  Water or water-releasing compounds · CPC title

• C08J2301/02

  Cellulose; Modified cellulose · CPC title

• C08J9/0061 Primary

  characterized by the use of several polymeric components · CPC title

• C08J9/0023

  containing oxygen · CPC title