Design of Intrinsic Polyimides via a Restricted Dihedral-Rotation Structural Strategy for Superior High-Temperature Capacitive Applications.
basic_science · Level V
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- Record sourced from PubMed, PMID 41999258.
- Also identified by DOI 10.1002/adma.202520134.
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Abstract
With the advancement of high-temperature electrical insulation technology, the limited energy-storage capacity of the intrinsic polyimide (PI) matrix severely restricts application in harsh environments. This limitation primarily stems from their intrinsic structures, which hinder the coordinated optimization of suppressed charge-transfer complexes (CTC), high glass-transition temperature (T<sub>g</sub>), and dielectric constant (ε<sub>r</sub>). In this work, intrinsic PI dielectrics with restricted dihedral-rotation structure were successfully constructed by employing ─Cl, ─CH<sub>3</sub>, and ─CF<sub>3</sub>. Such a structure effectively regulates molecular chain rigidity, thereby maintaining a high T<sub>g</sub> while preventing film failure induced by excessive internal stress. Additionally, highly electronegative substituents, together with restricted dihedral-rotation structure, synergistically suppress CTC, thereby further enhancing breakdown strength (E<sub>b</sub>). Notably, ─Cl substituent compensates for the reduction in ε<sub>r</sub> resulting from CTC suppression, thereby enhancing the ε<sub>r</sub> and ultimately yielding outstanding discharged energy density (U<sub>d</sub>) of 11.47 J/cm<sup>3</sup> @150°C and 9.46 J/cm<sup>3</sup> @200°C. Furthermore, HBPDA/6FClTP exhibits outstanding power density and long-term stability, with the fabricated high-temperature-resistant stacked-film capacitor device showing excellent capacitance stability. This chemical modification strategy effectively achieves synergistic optimization of CTC suppression, T<sub>g</sub>, and ε<sub>r</sub>, thereby providing valuable guidance for the development of scalable, high-performance polymer capacitors.