Method of preparing a conductive film
View Patent ↗The invention provides a method for producing a conductive film that generates an electric current via field emission of electrons, which method comprises incorporating an electrically conductive material into a thermoplastic polymer. The invention also provides a conductive film and a method for generating an electric current via field emission of electrons.
1. A method for producing a conductive film that generates an electric current via field emission of electrons comprising:
(i) providing a thermoplastic polymer comprising pores and having a flow temperature of about 100° C. or higher,
(ii) subjecting the thermoplastic polymer to a vacuum while contacting at least one surface of the thermoplastic polymer with a medium comprising (a) a liquid having a vapor pressure and (b) an electrically conductive material, such that at least some of the medium is introduced into the thermoplastic polymer,
(iii) removing the liquid having a vapor pressure from the thermoplastic polymer, such that the electrically conductive material remains in the thermoplastic polymer, and
(iv) forming the thermoplastic polymer into a conductive film by applying a pressure to the thermoplastic polymer at or above the flow temperature of the thermoplastic polymer such that the resulting conductive film has a porosity of about 2% or less.
2. The method of claim 1 , wherein the thermoplastic polymer is contacted with the medium before subjecting the thermoplastic polymer to a vacuum.
3. The method of claim 1 , wherein the thermoplastic polymer is contacted with the medium after subjecting the thermoplastic polymer to a vacuum.
4. The method of claim 1 , wherein the thermoplastic polymer comprises open-celled pores.
5. The method of claim 1 , wherein the thermoplastic polymer comprises closed-celled pores.
6. The method of claim 1 , wherein the thermoplastic polymer is selected from the group consisting of polyarylene ethers, polyetheretherketone, polyetherketoneketone, polyetherimide, cyclized polyimides, fluorinated polyimides, polybenzimidazole, polybenzoxazole, polyolefins, polycarbonares, polyimides, polyesters, cyclic polyolefins, and elastomers.
7. The method of claim 6 , wherein the thermoplastic polymer is a polyetheretherketone.
8. The method of claim 6 , wherein the thermoplastic polymer is a polyolefin.
9. The method of claim 1 , wherein the electrically conductive material consists of carbon black.
10. The method of claim 1 , wherein the electrically conductive material consists of carbon fibers.
11. The method of claim 1 , wherein the electrically conductive material consists of carbon nanotubes.
12. The method of claim 1 , wherein the electrically conductive material comprises particles comprising a metal.
13. The method of claim 1 , wherein the thermoplastic polymer further comprises particles of a dielectric material.
14. The method of claim 13 , wherein the dielectric material is silica.
15. The method of claim 1 , wherein the thermoplastic polymer is immersed in the medium.
16. The method of claim 1 , wherein the liquid having a vapor pressure is mesitylene.