Polyimide Films Based on β-Cyclodextrin Polyrotaxane with Low Dielectric and Excellent Comprehensive Performance

Abstract

In order to prepare polyimide (PI) films with a low dielectric constant and excellent comprehensive performance, a two-step method was employed in this study to integrate β-cyclodextrin into a semi-aromatic fluorine-containing polyimide ternary system. By introducing trifluoromethyl groups to reduce the dielectric constant, the dielectric constant was further reduced to 2.55 at 10 MHz. Simultaneously, the film exhibited noteworthy thermal stability (a glass transition temperature exceeding 300 °C) and a high coefficient of thermal expansion. The material also demonstrated outstanding mechanical properties, boasting a strength of 122 MPa and a modulus of 2.2 GPa, along with high optical transparency (transmittance reaching up to 89% at 450 nm). Moreover, the inherent high transparency of colorless polyimide (CPI) combined with good stretchability contributed to the attainment of a low dielectric constant. This strategic approach not only opens up new opportunities for novel electroactive polymers but also holds potential applications in flexible displays, circuit printing, and chip packaging.

Versatile Landscape of Low-k Polyimide: Theories, Synthesis, Synergistic Properties, and Industrial Integration

“…The permittivity of materials is intimately associated with the molar polarization and molar volume of dipoles. , So, the reduction of the permittivity is mainly concerned with the concentration and position of polar groups as well as other structural factors in a molecule. In addition, introducing small molecular elements to reduce the electron density or strong electronegativity atoms to weaken the induced polarization can also help to achieve the purpose of reducing the permittivity. , (2) Create a porous structure. The introduction of micropores will significantly reduce the dielectric properties due to the low permittivity of air ( k ≈ 1.0) .…”

“…In addition, introducing small molecular elements to reduce the electron density or strong electronegativity atoms to weaken the induced polarization can also help to achieve the purpose of reducing the permittivity. 45,46 (2) Create a porous structure. The introduction of micropores will significantly reduce the dielectric properties due to the low permittivity of air (k ≈ 1.0).…”