Thermally-drawn fiber including porosity
There is provided a fiber that includes a fiber material disposed along a longitudinal-axis fiber length. A porous domain has a porous domain length along at least a portion of the fiber length, within the fiber material. The porous domain includes solid-phase material regions and fluid-phase interstitial regions that are both along the porous domain length and across the porous domain, for multi-dimensional porosity of the porous domain.
1. A fiber comprising:
at least one fiber material, including a non-porous outer cladding polymer disposed along a longitudinal-axis fiber length;
a porous domain having a porous domain length along at least a portion of the fiber length and having a porous domain cross section disposed fully interior to the non-porous outer cladding polymer, the porous domain including solid-phase polymer material regions comprising polymer structures packed in a random configuration along the porous domain length and fluid-phase interstitial regions, between the polymer structures, comprising a solvent for the solid-phase polymer, said cladding polymer being chemically resistant to said solvent for the solid-phase polymer; and
wherein said solid-phase material regions and said fluid-phase interstitial regions extend both along the porous domain length and across the porous domain cross section, for three-dimensional porosity of the porous domain.
2. The fiber of claim 1 wherein regions of either one of the solid-phase material and the fluid-phase interstices are interconnected in that phase, separate from the other phase, for isotropic porosity of the porous domain.
3. The fiber of claim 1 wherein regions of either one of the solid-phase material and the fluid-phase interstices are interconnected in that phase, separate from the other phase, for three-dimensional porosity along the longitudinal-axis porous domain length.
4. The fiber of claim 1 wherein regions of either one of the solid-phase material and fluid-phase interstices are interconnected in that phase, separate from the other phase, for three-dimensional porosity across the porous domain cross section.
5. The fiber of claim 1 wherein solid-phase material regions are interconnected in the solid phase, separate from the fluid phase, and form a continuous path through the interconnected solid-phase material regions along the porous domain length.
6. The fiber of claim 1 wherein solid-phase material regions are interconnected in the solid phase, separate from the fluid phase, and form a continuous path through the interconnected solid-phase material regions across the porous domain cross section.
7. The fiber of claim 1 wherein fluid-phase interstitial regions are interconnected in the fluid phase, separate from the solid phase, and form a continuous path through fluid-phase regions along the porous domain length.
8. The fiber of claim 1 wherein fluid-phase interstitial regions are interconnected in the fluid phase, separate from the solid phase, and form a continuous path through fluid-phase regions across the porous domain cross section.
9. The fiber of claim 1 wherein the fluid-phase interstitial regions comprise pores within the solid-phase polymer material regions.
10. The fiber of claim 1 wherein the polymer structures comprise polymer spheres packed in a random configuration along the porous domain length and the fluid-phase interstitial regions comprise interstices between the polymer spheres.
11. The fiber of claim 1 wherein the polymer structures comprise interconnected polymer struts, and wherein the fluid-phase interstitial regions comprise pores between the polymer struts.
12. The fiber of claim 1 wherein the fluid-phase interstitial regions comprise a liquid including the solvent.
13. The fiber of claim 1 wherein the fluid-phase interstitial regions comprise fluid-filled spheres packed in a random configuration along the porous domain length.
14. The fiber of claim 13 wherein the fluid-filled spheres comprise liquid-filled spheres.
15. The fiber of claim 1 wherein the fluid-phase interstitial regions comprise an interconnected population of pores that are filled with a liquid including the solvent.
16. The fiber of claim 1 wherein the fluid-phase interstitial regions comprise an interconnected population of pores that provides a continuous path through the pores along the length of the porous domain.
17. The fiber of claim 1 wherein the fluid-phase interstitial regions comprise an interconnected population of pores that provides a continuous path through the pores across the porous domain cross section.
18. The fiber of claim 1 wherein regions of least one of the solid-phase material and fluid-phase interstices are interconnected in that phase, separate from the other phase, and include a conducting medium, forming a continuous path of conductivity along the porous domain length.
19. The fiber of claim 1 wherein regions of least one of the solid-phase material and fluid-phase interstices are interconnected in that phase, separate from the other phase, and include a conducting medium, forming a continuous path of conductivity across the porous domain cross section.
20. The fiber of claim 1 wherein the solvent comprises an electrolytic liquid.
21. The fiber of claim 20 wherein the electrolytic liquid includes a salt selected from the group consisting of LiClO 4 , LiCF 3 SO 3 , LiTFSI, and TEABF 4 .
22. The fiber of claim 1 wherein the porous domain of the fiber is at a temperature below a phase separation temperature characteristic of a liquid solution of said solid-phase polymer and said solvent for said solid-phase polymer.
23. The fiber of claim 22 wherein said phase separation temperature is between about 100° C. and about 300° C.
24. The fiber of claim 20 further comprising:
an electrically conducting anode in contact with the porous domain along the porous domain length interior to said cladding polymer;
an electrically conducting cathode in contact with the porous domain along the porous domain length interior to said cladding polymer; and
a first electrically conducting current collector in contact with the anode along the porous domain length interior to said cladding polymer and a second electrically conducting current collector in contact with the cathode along the porous domain length interior to said cladding polymer.
25. The fiber of claim 1 wherein the cladding polymer has a viscosity that is less than about 10 8 Poise at a temperature between about 150° C. and about 300° C. and wherein the porous domain of the fiber is at a temperature below a phase separation temperature between about 150° C. and about 300° C. that is characteristic of a liquid solution of said solid-phase polymer and said solvent for said solid phase polymer disposed in the porous domain.
26. The fiber of claim 1 wherein the fiber material comprises one of cyclic olefin polymer and cyclic olefin copolymer.
27. The fiber of claim 1 wherein the porous domain cross section includes the longitudinal axis of the fiber.
28. The fiber of claim 1 wherein the solvent comprises a carbonate ester.
29. The fiber of claim 1 wherein said solvent is selected from gamma-butyrolactone, propylene carbonate, ethylene carbonate, dimethyl carbonate triethylene glycol, and dimethyl sulfoxide.
30. The fiber of claim 1 wherein said polymer is selected from high-density polyethylene, polypropylene, polymethylpentene, polycaprolactone, polylactide, and polyvinylidene fluoride.
31. The fiber of claim 1 wherein the porous domain further includes a salt.
32. The fiber of claim 1 wherein the solid-phase material regions and fluid-phase interstitial regions of the porous domain are ionically-conductive.
33. The fiber of claim 1 wherein the solid-phase material regions and fluid-phase interstitial regions of the porous domain are electrolytic.