Thermally Robust Zirconia Nanorod/Polyimide Hybrid Films as a Highly Flexible Dielectric Material

Abstract

In this study, a strategy for the fabrication of zirconia-polyimide (ZrO 2 -PI) nanohybrid films with high permittivity (high-k), thermal stability, and excellent mechanical properties has been developed. A colloidal suspension of ZrO 2 nanorods was prepared using the facile microwave-hydrothermal treatment approach. The ZrO 2 -PI nanohybrid film was fabricated by casting an aqueous solution containing water-soluble poly(amic acid) ammonium salt (PAS) and water-dispersible ZrO 2 nanorods followed by thermal imidization. Atomic force microscopy and scanning electron microscopy images indicated that the ZrO 2 nanorods were uniformly dispersed in the PI matrix. Because of the high permittivity of the ZrO 2 nanorods and good compatibility between polyimide and ZrO 2 as well as the nanosize of ZrO 2 , the permittivity increased to 5.1 as the ZrO 2 concentration reached 10% at 10 Hz, while the dielectric loss was as low as 0.05 at 10 Hz. The prepared ZrO 2 -PI nanohybrid films had excellent heat resistance with quite low coefficients of thermal expansion (CTE), as low as 16.3 ppm/K. The ZrO 2 -PI nanohybrid films have excellent thermal stability and good mechanical flexibility. Moreover, no distinct changes were observed for the PAS solution over a storage time of 3 months, after which the nanohybrid film could still be successfully synthesized by thermal imidization. In addition, the water uptake of the ZrO 2 -PI nanohybrid film was approximately 2.5% under 60% relative humidity. The high stability of the PAS precursor, good flexibility, enhanced permittivity, and low CTE behavior of the ZrO 2 -PI nanohybrid films could make this strategy attractive for the ecofriendly design of dielectric polymer nanohybrids as well as for the fabrication of nanohybrid films with potential applications in high charge-storage capacitors and organic field-effect transistors (OFETs) in the flexible electronics industry.

Highly Foldable, Super-Sensitive, and Transparent Nanocellulose/Ceramic/Polymer Cover Windows for Flexible OLED Displays

“…A high dielectric constant could be ascribed to introduction of ZrO 2 . ZrO 2 has a high dielectric constant and high polarizing ability as a filler. , Polarization increases with the increase in ZrO 2 loading. What’s more, a large number of organic–inorganic interface layers may be formed in the hybrid films after ZrO 2 introduction, resulting in the increase in interface polarization. , When the frequency is increased, the dielectric loss of all samples decreases (Figure b).…”

“…ZrO 2 has a high dielectric constant and high polarizing ability as a filler. 43,44 Polarization increases with the increase in ZrO 2 loading. What's more, a large number of organic−inorganic interface layers may be formed in the hybrid films after ZrO 2 introduction, resulting in the increase in interface polarization.…”

High glass transition temperature and ultra‐low thermal expansion coefficient polyimide films containing rigid pyridine and bisbenzoxazole units

“…Doping inorganic fillers, such as SiO 2 , W 2 ZrO 8 , ZnO 2 , and carbon nanotubes, can reduce the CTE of PI films. [14][15][16][17][18][19] Nevertheless, inorganic fillers have disadvantages of poor dispersibility and easy agglomeration, which decrease the mechanical properties of polyimide films. Cross-linking structures can be introduced to inhibit movement of molecular chain, such as covalent bond cross-linking.…”

Polyimide Films Containing Trifluoromethoxy Groups with High Comprehensive Performance for Flexible Circuitry Substrates

“…1−3 With the rapid development of flexible electronic materials in recent years, high-performance colorless and transparent PI films have been favorable candidates for flexible substrates of foldable screens, 4 solar panels, 5 and other electronic equipment. 6,7 At present, commercial optical polymer films for flexible circuitry substrates are mainly focused on polyolefins and polyesters. Nevertheless, these materials usually suffer poor thermal properties and dimensional stability.…”

“…Polyimide (PI) is a high-performance polymer with exceptional properties, such as outstanding thermal stability, remarkable chemical resistance, excellent mechanical properties, high transparency, and low dielectric constant, and has been extensively applied in the aerospace, microelectronics, and optoelectronics industries. − With the rapid development of flexible electronic materials in recent years, high-performance colorless and transparent PI films have been favorable candidates for flexible substrates of foldable screens, solar panels, and other electronic equipment. , …”