Low dissipation factor (Df) at high-frequency is crucial for the applications of dielectric materials in next generation mobile communication. However, the relationship between the high-frequency Df and the molecular structure...

High dielectric constant polymers have been widely studied and concerned in modern industry, and the induction of polar groups has been confirmed to be effective for high permittivity. However, the way of connection of polar groups with the polymer backbone and the mechanism of their effect on the dielectric properties are unclear and rarely reported. In this study, three polyimides (C0-SPI, C1-SPI, and C2-SPI) with the same rigid backbone and different linking groups to the dipoles were designed and synthesized. With their rigid structure, all of the polyimides show excellent thermal stability. With the increase in the flexibility of linking groups, the dielectric constant of C0-SPI, C1-SPI, and C2-SPI enhanced in turn, showing values of 5.6, 6.0, and 6.5 at 100 Hz, respectively. Further studies have shown that the flexibility of polar groups affected the dipole polarization, which was positively related to the dielectric constant. Based on their high permittivity and high temperature resistance, the polyimides exhibited outstanding energy storage capacity even at 200 °C. This discovery reveals the behavior of the dipoles in polymers, providing an effective strategy for the design of high dielectric constant materials.

The high permittivity of polymer dielectrics facilitates their use in the electronics industry. Compared to inorganic ceramics and composites, intrinsic high permittivity polymer dielectrics have the advantages of easy solution processing and better homogeneity. The permittivity of common polymers is generally low, hence it would be worthwhile to explore avenues for augmenting the permittivity of polymer dielectrics via judicious and efficient structural design. The effective strategies used to increase the permittivity of intrinsic polymers encompass elevating local polarisabilities by fortifying electron delocalisation capabilities, exploiting ion pairs to generate atomic clusters with larger dipole moments, amplifying dipole density, augmenting dipole mobility, and so forth. Due to the rigidity and flexibility of the polymer backbone's decisive influence on the dielectric's all‐around performance, its selection also requires a total consideration of the requirements of practical applications. This work provides an overview and a brief evaluation of the dominant design strategies and mentions possible future design paradigms for polymer dielectrics.

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Two new bioderived diamines with two cis-fused cyclopentane ring structure, bis(4-aminophenyl) (octahydropentalene-2,5-diyl)dicarbamate (OAC) and 4,4'-((octahydropentalene-2,5-diyl)bis(oxy))dianiline (OOD), were designed and synthesized from natural citric acid for the first time. Two series...