Conductive polymers with reduced radiative transport and emissivity for insulating materials
An insulation useful in the field of building materials, refrigeration, cryogenics, and shipping. The insulation has reduced radiative heat transfer by applying coating to the insulation material in order to alter the emissivity, including the infrared electromagnetic spectrum.
1. A material comprising:
an insulating material;
a low-emissivity coating on a surface of said insulating material;
wherein said low-emissivity coating has a thermal conductivity of less than or equal to 0.6 W/m-K and an emissivity less than or equal to 0.5 of electromagnetic radiation having a wavelength selected from the range of 1 mm to 2.5 μm.
2. The material of claim 1 , wherein said low-emissivity coating comprises an electrically conducting polymer.
3. The material of claim 2 , wherein said polymer comprises polypyrrole, poly(3,4-ethylenedioxythiophene polyacetylene, polyaniline, polythiophene, poly(para-phenylene), poly(phenylenevinylene), polyfuran or a combination thereof.
4. The material of claim 1 , wherein said low-emissivity coating comprises an oxide semiconductor.
5. The material of claim 4 , wherein the oxide semiconductor is transparent and comprises tin oxide, indium oxide, titanium oxide, zinc oxide, boron tin trioxide or a combination thereof.
6. The material of claim 1 , wherein said low-emissivity coating is a thin film having a thickness less than or equal to 100 atomic layers.
7. The material of claim 1 , wherein said low-emissivity coating reflects greater than 25% of total electromagnetic radiation having a wavelength selected from 2.5 μm to 20 μm.
8. The material of claim 1 , wherein said low-emissivity coating reflects greater than 50% of total electromagnetic radiation having a wavelength selected from 5 μm and 15 μm.
9. The material of claim 1 , wherein the insulating material comprises:
a plurality of insulating particles;
a polymer crosslinking the plurality of insulating particles, wherein the polymer comprises a cyanoacrylate;
wherein the plurality of insulating particles have a packing density greater than or equal to 50%; and
wherein the insulating material has a thermal conductivity less than or equal to 0.1 W/m-K.
10. The material of claim 9 , wherein the cyanoacrylate comprises methyl cyanoacrylate, ethyl cyanoacrylate, butyl cyanoacrylate, octyl cyanoacrylate or a combination thereof.
11. The material of claim 9 , wherein the plurality of insulating particles comprise a plurality of hollow microspheres.
12. The material of claim 11 , wherein the plurality of hollow microspheres comprise:
a plurality of small hollow microspheres having a diameter selected from the range of 0.01 mm to 0.03 mm; and
a plurality of large hollow microspheres having a diameter selected from the range of 0.1 mm to 1 mm.
13. The material of claim 11 , wherein the hollow microspheres have an internal pressure less than or equal to 0.001 atm.
14. The material of claim 1 , wherein the insulating material comprises close-packed hollow capsules, wherein each capsule is at least partially covered with a layer of a polymer adhesive having a substantially uniform thickness of at least 1 monolayer which bonds the hollow capsules together.
15. The material of claim 14 , wherein a layer of polymer adhesive is interposed between neighbouring capsules.
16. The material of claim 14 , wherein at least some of the hollow capsules are in direct contact with one another.
17. The material of claim 14 , wherein the polymer adhesive comprises at least one polymer adhesive selected from polycyanoacrylates, polyvinyl alcohols, polypyrroles, poly(alkylenedioxythiophenes), polyimides, polyazomethines, polyureas, polyamides, polyimide-polyamides, polythioureas, polyethylene terephthalate, and alucones.
18. A method comprising:
providing an insulating material;
coating a surface of said insulating material with a low-emissivity coating;
wherein said low-emissivity coating has a thermal conductivity of less than or equal to 0.6 W/m-K and an emissivity less than or equal to 0.5 of electromagnetic radiation having a wavelength selected from the range of 1 mm to 0.2 μm.
19. The method of claim 18 , wherein said step of coating is performed in the vapor phase.
20. The method of any of claim 18 , wherein the step of providing an insulating material further comprises:
providing a plurality of insulating particles with a packing density greater than or equal to 50%;
depositing or having water on a least a portion of an outer surface of the plurality of insulating particles; and
reacting at least one type of cyanoacrylate monomer assisted by the water to generate a polymer network, thereby crosslinking the plurality of insulating particles and generating an insulating material;
wherein the insulating material has a thermal conductivity less than or equal to 0.1 W/m-K.