Nanodiamond/Polyimide High Temperature Dielectric Films for Energy Storage Applications

Abstract

CP2 polyimide (prepd. from 6FDA and 1,3-bis (3-aminophenoxy) benzene) was blended with (1-50 wt.%) detonation nanodiamonds (DND, pristine, acetone-washed, and 4-(2,4,6-trimethylphenoxy) benzoic acid-functionalized), and the blends were evaluated as thin films for its potential utility in high-energy-density capacitors that would have stable dielectric properties over a wide temperature range (-55 to 300°C) and at frequencies up to or greater than 100 kHz. Both the dielectric storage and loss increased substantially with DND content. Surface functionalization (with the above benzoic acid derivative) significantly reduced the dielectric loss, while the use of acetone-washed DNDs had no effect on the dielectric loss. DND was also blended with CP2 via in-situ polymerization and found to have little effect on the dielectric properties.