Heat dissipation has become an important challenge and technical bottleneck for the rapid development of high‐frequency microelectronic devices and high‐voltage electrical equipment. Thus, there is a great urgent need for high‐performance intrinsically thermally conductive polymer (ITCP) to realise effective heat dissipation. In recent year, the ITCP has received extensive attention due to excellent overall performances and clear advantages over conventional heat conductive polymer composites. The thermal transport physics and its relation with the multiscale chain conformations in polymers with diverse morphologies are reviewed. Then, the current understanding of how the chemistry of polymers, multiscale chain morphologies and conformations would affect phonon transport and the resulting thermal conductivity (TC) in both amorphous and crystalline polymers to unveil the important chemistry‐structure‐property relationships is discussed and anaysed. The latest advances in engineering ITCP from oriented fibre to bulk amorphous states for a high TC are summarised. Lastly, the challenges, prospects and outlook of ITCP have been proposed. The authors anticipate that the present paper will spire more fundamental and applied research in the intrinsic polymer dielectrics field to advance scientific understanding and industrial applications.

Highlights: (1) The thermal transport physics in polymers with diverse morphologies is reviewed. (2) The macroscopic, microscopic and molecular level understanding on TC are discussed. (3) The challenges, prospects and outlook of ITCP have been proposed.image

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.

The polarisation mechanism of dielectrics and the design strategies of intrinsically high dielectric polymers are reviewed. A brief evaluation of these strategies is also presented in the context of the dielectric polarisation mechanism. Finally, we summarise the possible future directions of design strategies for intrinsic high dielectric polymers and some valuable suggestions for improving the permittivity of the polymer dielectrics.image

We have witnessed the flourish of bioelectronics, brain–computer interface, and brain science programme in recent decades. In this review, the up‐to‐date advances of dielectric, piezoelectric, and ferroelectric nanomaterials in the biomedical applications are summarised. Biomolecular detection methods have been developed, including dielectric‐gated field‐effect transistor, dielectrophoresis, non‐linear dielectric response, and optical tweezer. Endogenous bioelectricity is a crucial in cell proliferation, migration, differentiation, intracellular communication, neuronal activity, tissue growth. Piezoelectric and ferroelectric materials can be utilised as energy transducer to monitor physiological signal, such as blood pressure or respiration, and directly stimulate cell differentiation, neuronal regeneration, tissue repairment etc. They can also catalyse the electrochemical reaction of organisms through piezoelectricity. The intrinsic relevance between neuronal and ferroelectric polarisation signals inspires the application of the ferroelectrics in the modern intelligent bioelectronics like the artificial retina.

In this review, we summarise the latest advances of dielectric, piezoelectric, and ferroelectric nanomaterials in the biomedical applications. These materials can be utilised as energy transducer to monitor physiological signal, directly stimulate cell differentiation, neuronal regeneration, and tissue repairment.image

The concept of self‐healing dielectric polymers has been heatedly discussed, with the expectation of high damage resistance and longer service time. However, there is still a lack of analysis on the competitive relationship between electrical degradation and self‐healing. The authors discussed this relationship in two stages: the design of self‐healing strategies and the operation of self‐healing polymers. Since the requirements for excellent insulating or mechanical properties are not consistent with the demands for high self‐healing capability, trade‐offs are necessary during the design of self‐healing polymeric systems. In the operation stage of dielectric polymers, some key factors that affect the service lifetime of non‐autonomous self‐healing dielectric polymers are analysed, including the efficiency and repeatability of self‐healing, and the frequency of healing maintenance. For autonomous self‐healing dielectrics, the simultaneous processes of ageing and healing are investigated using a self‐healing epoxy resin based on microcapsules and in situ‐generated radicals. A quicker recovery of insulating properties, in terms of partial discharge magnitude, was observed under appropriate healing voltages. However, the self‐healing ability might vanish when the voltage was too high, verifying the competitive relationship between electrical degradation and self‐healing.

The authors discussed the competitive relationship between degradation and healing in self‐healing dielectric polymers. This relationship should be considered during both the design of self‐healing strategy and the operating stage. By theoretical analysis and experiments, the competitions and trade‐offs between working properties and self‐healing ability, between the convenience of maintenance and an acceptable extent of property degradation, and between electrical ageing and self‐healing performance are discussed.image

Recently, demands for high‐performance polymer film capacitors at elevated temperatures have become more urgent. High dielectric constant is essential for dielectric materials to achieve substantial energy density at relatively low electric fields, which is of great significance to practical applications, while improving the permittivity of high‐temperature polymer dielectrics without a remarkable deterioration in other electrical properties still remains a challenge. Here, a polymer nanocomposite containing z‐aligned high‐k nanowires sandwiched by e‐beam evaporation deposited Al₂O₃ films was developed based on the optimal structure proposed by the phase‐field simulation. It is found that z‐aligned nanowires are more effective in promoting the dielectric constant than random‐aligned ones, and a large increase in dielectric constant is observed at relatively low content of nanofillers. Outer insulating layers effectively suppress the electric conduction and improve the breakdown strength. Consequently, the nanocomposite with only 1 volume fraction of z‐aligned nanowires exhibits a breakdown strength, electrical resistance, and charge–discharge efficiency as high as neat PEI, but more than twice the discharged energy density than it at 150 °C. This study realises the optimal structure predicted by simulation in experiment, obtaining high‐permittivity, high‐temperature nanocomposites at no expense of other electrical properties, and making it possible to achieve high discharged energy density at relatively low electric fields.

This work develops a polymer nanocomposite containing z‐aligned high‐k nanowires sandwiched by e‐beam evaporation deposited Al2O3 films. The nanocomposite shows a largely increased dielectric constant at relatively low doping concentration of nanofillers, where the breakdown strength, electrical resistance and dielectric loss are approximately equal to that of neat polymer. The nanocomposite with only 1 volume fraction of z‐aligned nanowires delivers more than twice the discharged energy density than neat polymer and maintain a high charge–discharge efficiency at 150 °C.image