Flexible acrylic-polyurethane/copper composites with a frequency and temperature-independent permittivity

Capacitors with a high dielectric constant and low dielectric loss are highly demanded for electronic applications, such as electric devices and energy storage. To enhance the performance of those electronic applications, it is of great significance to achieve capacitors with stable dielectric property both in a broad ranges of frequency and temperature. In this research, flexible Acrylic-polyurethane/copper (APU/Cu) composites with different filler fractions were successfully synthesized. Excellent flexibility of APU/Cu composites is maintained even when Cu particles reached to 19.11 vol%. The dielectric and thermal properties of APU/Cu composites were systematically investigated. Enhanced dielectric constant and lower dielectric loss were achieved. Meanwhile, it is found that the permittivity fluctuated slightly with the increase of frequency and temperature, suggesting that permittivity was independent on frequency and temperature over a broad range. This research shed lights on the application of APU/Cu composites in flexible thin-film capacitors and stretchable electronic devices.