Cellulose enabled orientationally ordered flexible gels
Disclosed are cellulose-based flexible gels containing cellulose nanorods, ribbons, fibers, and the like, and cellulose-enabled inorganic or polymeric composites, wherein the gels have tunable optical, heat transfer, and stiffness properties. The disclosed gels are in the form of hydrogels, organogels, liquid-crystal (LC) gels, and aerogels, depending on the solvents in the gels.
1. A cellulose aerogel that has the combined properties of high transmissivity of electromagnetic radiation of larger than 80% at the visible spectrum, tunable birefringence, low thermal conductivity of 5-25 mW/(m·K) and compression Young's modulus of 1-500 kPa, comprising:
a) oxidized cellulose nanofibers with the diameter between 3 nm and 10 nm;
b) at least one surface modifying agent; and
c) at least one crosslinking agent, wherein the cellulose aerogel exhibits a haze or diffusive transmission of less than 10%.
2. The cellulose aerogel of claim 1 , wherein the surface modifying agent is selected from the group consisting of C1-C6 linear or branched, saturated or unsaturated alkylamine compounds; low molecular weight compounds comprising a cationic moiety; oligomers; and polymers.
3. The cellulose aerogel according to claim 1 , wherein the surface modifying agent comprises one or more of allylamine, carbamoylcholine chloride, 2-(carbamoyloxy)-N,N,N-trimethylethan-aminium, and methoxy polyethylene glycol amine.
4. The cellulose aerogel according to claim 1 , wherein the crosslinking agent comprises one or more of hydrochloric acid, acetic acid, nitric acid, sulfuric acid, and phosphoric acid.
5. The cellulose aerogel according to claim 1 , wherein the crosslinking agent comprises polysiloxane.
6. The cellulose aerogel according to claim 5 , wherein the cellulose aerogel comprises a polysiloxane network that comprises polymerized methyltrimethoxysilane.
7. The cellulose aerogel according to claim 1 , wherein the aerogel is a hydrophobic aerogel.
8. The cellulose aerogel according to claim 7 , wherein the hydrophobic aerogel has a contact angle in the range of 90°-170°.
9. The cellulose aerogel according claim 1 , wherein the cellulose nanofibers comprise (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO)-oxidized cellulose nanofiber.
10. A cellulose aerogel that has the combined properties of high transmissivity of electromagnetic radiation of larger than 80% at the visible spectrum, tunable birefringence, low thermal conductivity of 5-25 mW/(m·K) and compression Young's modulus of 1-500 kPa, comprising:
a) oxidized cellulose nanofibers with the diameter between 3 nm and 10 nm;
b) at least one surface modifying agent; and
c) at least one crosslinking agent.
11. The cellulose aerogel according claim 10 , wherein the cellulose nanofibers comprise (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO)-oxidized cellulose nanofiber.
12. The cellulose aerogel of claim 10 , wherein the surface modifying agent is selected from the group consisting of C1-C6 linear or branched, saturated or unsaturated alkylamine compounds; low molecular weight compounds comprising a cationic moiety; oligomers; and polymers.
13. The cellulose aerogel according to claim 12 , wherein the surface modifying agent comprises one or more of allylamine, carbamoylcholine chloride, 2-(carbamoyloxy)-N,N,N-trimethylethan-aminium, and methoxy polyethylene glycol amine.
14. The cellulose aerogel according to claim 10 , wherein the crosslinking agent comprises one or more of hydrochloric acid, acetic acid, nitric acid, sulfuric acid, and phosphoric acid.
15. The cellulose aerogel according to claim 10 , wherein the crosslinking agent comprises polysiloxane.
16. The cellulose aerogel according to claim 15 , wherein the cellulose aerogel comprises a polysiloxane network that comprises polymerized methyltrimethoxysilane.
17. The cellulose aerogel according to claim 10 , wherein the aerogel is a hydrophobic aerogel.
18. The cellulose aerogel according to claim 17 , wherein the hydrophobic aerogel has a contact angle in the range of 90°-170°.