Thermoelectric polymer aerogels and methods of fabrication thereof
This disclosure provides systems, methods, and apparatus related to thermoelectric polymer aerogels. In one aspect, a method includes depositing a solution on a substrate. The solution comprises a thermoelectric polymer. Solvent of the solution is removed to form a layer of the thermoelectric polymer. The layer is placed in a polar solvent to form a gel comprising the thermoelectric polymer. The gel is cooled to freeze the polar solvent. The gel is placed in a vacuum environment to sublimate the polar solvent from the gel to form an aerogel comprising the thermoelectric polymer.
1. A method comprising:
(a) depositing a solution on a substrate, the solution comprising a thermoelectric polymer;
(b) removing solvent of the solution to form a layer of the thermoelectric polymer;
(c) placing the layer in a polar solvent to form a gel comprising the thermoelectric polymer;
(d) cooling the gel to freeze the polar solvent; and
(e) placing the gel in a vacuum environment to sublimate the polar solvent from the gel, forming an aerogel comprising the thermoelectric polymer.
2. The method of claim 1 , wherein the thermoelectric polymer comprises a first polymer and a second polymer, wherein the first polymer is miscible in the solvent, and wherein the second polymer is immiscible in the solvent.
3. The method of claim 1 , wherein the thermoelectric polymer is selected from a group consisting of poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) and poly(3,4-ethylenedioxythiophene):tris-p-toluenesulphonate (PEDOT:Tos).
4. The method of claim 1 , wherein the solution has a solid content of about 0.5% to 25% of the thermoelectric polymer in the solvent.
5. The method of claim 1 , wherein the layer has a thickness of about 200 microns to 2 millimeters.
6. The method of claim 1 , wherein removing the solvent of the solution comprises heating the substrate and the solution disposed thereon to a temperature, and wherein the temperature is below the boiling point of the solvent.
7. The method of claim 1 , wherein the polar solvent comprises water, and wherein the gel is a hydrogel.
8. The method of claim 1 , wherein the layer is placed in the polar solvent for about 1 minute to 30 minutes in operation (c).
9. The method of claim 1 , further comprising:
after operation (c), removing the gel from the substrate.
10. The method of claim 1 , wherein the rate of cooling in operation (d) is about 200° C./minute to 230° C./minute.
11. The method of claim 1 , wherein the polar solvent comprises water, wherein the gel is a hydrogel, and wherein the hydrogel is cooled to about 0° C. or lower to freeze the water of the gel in operation (d).
12. The method of claim 11 , wherein operation (d) is performed by placing the hydrogel in liquid nitrogen.
13. The method of claim 1 , wherein the vacuum environment includes a vacuum of about 150 torr or lower.
14. The method of claim 1 , wherein a crosslinking agent is not used in the method.
15. The method of claim 1 , further comprising:
after operation (e), placing the aerogel in a treatment solvent, wherein the treatment solvent is selected from a group consisting of ethylene glycol, sulfuric acid, dimethyl sulfoxide (DMSO), and an alcohol.
16. The method of claim 15 , wherein the aerogel is placed in the treatment solvent for about 5 minutes to 60 minutes.
17. The method of claim 1 , wherein the aerogel has a thickness of about 500 microns to 10 centimeters.