1. Preparation of polyimide films with ultralow dielectric loss at high frequency by reducing intermolecular friction.
- Author
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Qin, Yitian, Yin, Qian, Lyu, Junwei, Wang, Xu, and Liu, Xiangyang
- Subjects
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DIELECTRIC loss , *YOUNG'S modulus , *POLYIMIDE films , *POLYIMIDES , *TELECOMMUNICATION , *THERMAL properties - Abstract
Due to the rapid development of high frequency and high rate communication technology, polyimide (PI) films with ultra-low dielectric loss (D f) at high frequency, excellent thermal and mechanical properties are urgently needed. A series of PI films with ultra-low D f were prepared by introducing different mesogen units. Among them, one novel PI film with biphenyl liquid-crystal-like units (BAHQ-TFMB) achieve a recorded low D f of 0.00169 (10 GHz) which surpasses previous studies on pure PI bulk films. Importantly, the high degree of collinearity of the friction work (W f) and D f of PI films (Pearson's r = 0.992) was confirmed, which indicate that W f among PI macromolecules plays an important role in determining D f of PI films. To reveal underlying reason for reducing the W f and D f of PI films, the contribution of the degree of orientation and crystallinity of PI films with or without liquid-crystal-like structures were comparative studied. Through a two-dimensional orientation determinant, it is found that increasing the crystallinity of liquid-crystal-like PI films is the main contribution to reducing W f and corresponding D f of PI films while the orientation of PI films seems to have weak effect. Moreover, BAHQ-TFMB PI film exhibits excellent mechanical properties. The tensile strengths is 145.5 ± 12.0 MPa and Young's moduli is 4.76 ± 0.28 GPa. [Display omitted] • The PI film with biphenyl liquid-crystal-like units achieve a recorded low dielectric loss of 0.00169 (10 GHz). • The friction work (W f) among PI macromolecules plays an important role in determining D f of PI films. • Increasing the crystallinity of liquid-crystal-like PI films is the main contribution to reducing W f and D f of PI films. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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