Sustainable hybrid organic aerogels and methods and uses thereof
Highly porous, lightweight, and sustainable hybrid organic aerogels with ultra-low densities and excellent material properties and methods for preparing them are provided, including, e.g., PVA/CNF/GONS, RF/CNF/GONS, and PVA/CNF/MWCNT. The aerogels are modified to have a super-hydrophobic surface, thus leading to an extremely low swelling ratio and rate of moisture absorption.
1. An aerogel comprising:
a water-soluble organic polymer having a weight-average molecular weight
ranging from about 15,000 to about 150,000 Da,
cellulose nanofibrils and/or nanocrystals, and
water-soluble graphene oxide,
wherein the water-soluble polymer, and the cellulose nanofibrils and/or nanocrystals are cross-linked to each other with a crosslinker such that the water-soluble organic polymer is no longer water-soluble; and wherein the aerogel has a density of not more than about 100 kg/m 3 and a compressive modulus of about 50 kPa to about 500 kPa.
2. The aerogel of claim 1 , wherein the water-soluble organic polymer is a thermoplastic polymer.
3. The aerogel of claim 1 , wherein the water-soluble organic polymer is polyvinyl alcohol, polyethylene glycol, polyacrylamide, polyacrylic acid, polymethacrylic acid, or a combination of any two or more thereof.
4. The aerogel of claim 1 wherein the water-soluble polymer is polyvinyl alcohol.
5. The aerogel of claim 1 , wherein the water-soluble organic polymer is a thermoset polymer comprising at least 90 mol % water-soluble organic monomers.
6. The aerogel of claim 1 , wherein the water-soluble organic polymer is polymerized resorcinol-formaldehyde, phenol-formaldehyde, urea-formaldehyde, polyamic acid salt or a combination of any two or more thereof.
7. The aerogel of claim 1 , wherein the water-soluble polymer is polymerized resorcinol-formaldehyde.
8. The aerogel of claim 1 , wherein the crosslinker is sodium borate, boric acid, organic dialdehyde, or a combination of any two or more thereof.
9. The aerogel of claim 1 , wherein the cellulose nanofibrils or nanocrystals have a diameter of about 5 to about 30 nm and length of about 10 nm to about 8 micrometers.
10. The aerogel of claim 1 , wherein the water-soluble graphene is graphene oxide nanosheets.
11. The aerogel of claim 1 , further comprising a surface modifier.
12. The aerogel of claim 11 wherein the crosslinker is glutaraldehyde.
13. The aerogel of claim 11 wherein the surface modifier is a silane compound.
14. The aerogel of claim 13 wherein the silane is a trialkylsilane, a dialkylarylsilane, an alkyldiarylsilane, a triarylsilane, a trichlorosilane, or a combination of any two or more thereof.
15. The aerogel of claim 1 , having a specific compressive strength ranging from about 0.001 MPa/kg m 3 to about 0.1 MPa/kg m 3 .
16. The aerogel of claim 1 , having a strain-at-failure of at least about 60%.
17. The aerogel of claim 1 , having a porosity of at least about 90%.
18. The aerogel of claim 1 , having a thermal conductivity of about 10 mWm −1 K −1 to about 60 mWm −1 K −1 .
19. An insulation composition comprising an aerogel of claim 1 .
20. The insulation composition of claim 19 wherein the insulation is thermal insulation, acoustic insulation or electrical insulation.
21. An aerogel comprising:
a water-soluble organic polymer,
cellulose nanofibrils and/or nanocrystals, and
water-soluble graphene oxide,
wherein the water-soluble polymer and the cellulose nanofibrils and/or nanocrystals are cross-linked to each other with a crosslinker such that the water-soluble organic polymer is no longer water-soluble; and wherein the crosslinker is selected from the group consisting of sodium borate, boric acid, organic dialdehyde, or a combination of any two or more thereof.
22. A method of making the aerogel of claim 1 , the method comprising:
combining a water-soluble organic polymer, cellulose nanofibrils and/or nanocrystals, and a water-soluble graphene oxide in water;
cross-linking the water-soluble organic polymer and the cellulose nanofibrils and/or nanocrystals to each other, such that the water-soluble organic polymer is no longer water-soluble; and
removing the water from the resulting gel to form the aerogel.
23. The method of claim 22 , wherein the water-soluble polymer is polyvinyl alcohol or polymerized resorcinol-formaldehyde.
24. The method of claim 22 , wherein the water is removed by freeze-drying the gel to form the aerogel.
25. The method of claim 22 , wherein the aerogel comprises water-soluble graphene oxide, further comprising contacting a surface of the aerogel with a surface modifying agent to provide a surface-modified aerogel.