Thermally switchable dielectrics
View Patent ↗Precursor polymers to conjugated polymers, such as poly(phenylene vinylene), poly(poly(thiophene vinylene), poly(aniline vinylene), and poly(pyrrole vinylene), can be used as thermally switchable capacitor dielectrics that fail at a specific temperature due to the non-conjugated precursor polymer irreversibly switching from an insulator to the conjugated polymer, which serves as a bleed resistor. The precursor polymer is a good dielectric until it reaches a specific temperature determined by the stability of the leaving groups. Conjugation of the polymer backbone at high temperature effectively disables the capacitor, providing a ‘built-in’ safety mechanism for electronic devices.
1. A thermally switchable dielectric comprising a non-conjugated precursor polymer having a leaving group that eliminates upon heating to a specified temperature, thereby converting the non-conjugated precursor polymer from an insulator to an electrically conductive conjugated polymer, wherein the leaving group comprises a halogen.
2. A thermally switchable dielectric comprising a non-conjugated precursor polymer having a leaving group that eliminates upon heating to a specified temperature, thereby converting the non-conjugated precursor polymer from an insulator to an electrically conductive conjugated polymer, wherein the non-conjugated precursor polymer comprises poly[(2,3-diphenyl-p-phenylene)(2-halo-ethylene)] and wherein the leaving group comprises a halogen.
3. The thermally switchable dielectric of claim 2 , wherein the halo-comprises bromo- or iodo-.
4. The thermally switchable dielectric of claim 1 , wherein the non-conjugated precursor polymer comprises a precursor to poly(phenylene vinylene), poly(poly(thiophene vinylene), poly(aniline vinylene), or poly(pyrrole vinylene).
5. The thermally switchable dielectric of claim 2 , wherein the poly[(2,3-diphenyl-p-phenylene)(2-halo-ethylene)] further comprises at least one polar substituent on at least one of the diphenyl rings.
6. The thermally switchable dielectric of claim 5 , wherein the at least one polar substituent comprises a halogen.
7. The thermally switchable dielectric of claim 6 , wherein the halogen comprises chlorine or fluorine.
8. A capacitor comprising a thermally switchable dielectric between two electrodes that fails at a specific elevated temperature, wherein the thermally switchable dielectric comprises a non-conjugated precursor polymer having a leaving group that eliminates upon heating to the specific elevated temperature, thereby converting the non-conjugated polymer precursor from an insulator to an electrically conductive conjugated polymer, wherein the leaving group comprises a halogen.
9. A capacitor comprising a thermally switchable dielectric between two electrodes that fails at a specific elevated temperature, wherein the thermally switchable dielectric comprises a non-conjugated precursor polymer having a leaving group that eliminates upon heating to the specific elevated temperature, thereby converting the non-conjugated polymer precursor from an insulator to an electrically conductive conjugated polymer, wherein the non-conjugated precursor polymer comprises poly[(2,3-diphenyl-p-phenylene)(2-halo-ethylene)] and wherein the leaving group comprises a halogen.
10. The capacitor of claim 8 , wherein the non-conjugated precursor polymer comprises a precursor to poly(phenylene vinylene), poly(thiophene vinylene), poly(aniline vinylene), or poly(pyrrole vinylene).
11. The capacitor of claim 9 , wherein the poly[(2,3-diphenyl-p-phenylene)(2-halo-ethylene)] further comprises at least one polar substituent on at least one of the diphenyl rings.
12. The capacitor of claim 11 , wherein the at least one polar substituent comprises a halogen.
13. A method for thermally switching a capacitor, comprising:
providing a capacitor comprising a thermally switchable dielectric between two electrodes, wherein the thermally switchable polymer comprises a non-conjugated precursor polymer having a leaving group that eliminates at a specific elevated temperature, and
heating the capacitor to the specific elevated temperature wherein the dielectric fails due to the non-conjugated precursor polymer converting from an insulator to an electrically conductive conjugated polymer,
wherein the non-conjugated precursor polymer comprises poly[(2,3-diphenyl-p-phenylene)(2-halo-ethylene)] and wherein the halo—comprises chloro-, bromo-, or iodo-.
14. The method of claim 13 , wherein the specific elevated temperature is greater than about 90° C.
15. The method of claim 13 , wherein the specific elevated temperature is greater than about 180° C.