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Novel polymer‐based materials with highly thermally conductive and high‐mechanical properties have attracted extensive attention in the field of electronic packaging as thermal interface materials (TIMs), due to the development of electronic equipment to miniaturization and higher power density. However, how to achieve high‐thermal conductivity (exceed 5 W/m·K) with low‐filling content (below 30 vol%) is still the focus of attention. Herein, polymer‐based materials with excellent in‐plane thermal conductivity were prepared by a simple hot‐pressing strategy, and a series of nanocomposites with different orientations were controlled by the hot‐pressing times. As expected, compared with that of randomly dispersed 25 vol% BNNS/P(VDF‐HFP) nanocomposite and pristine P(VDF‐HFP), the in‐plane thermal conductivity of oriented 25 vol% BNNS/P(VDF‐HFP) is promoted by 249% and 3057%, respectively. In contrast to randomly dispersed composites, oriented BNNS/P(VDF‐HFP) at loadings above 10 vol% begin to show an encouraging upward trend. This is because the orientation of BNNS can significantly reduce the percolation threshold and construct an efficient heat conduction network under low‐filling volume. Therefore, this technology can provide new ideas for the development of electronic packaging technology.

The free volume theory and trap model of nano-modified composite materials were combined to explain the breakdown voltage mechanism.

New types of carbon nanomaterials, such as multiwalled carbon nanotube (MWCNT) and graphene nanoplatelet (GNP), have attracted much attention in enhancing the thermal conductivity of polymers. However, due to the high electric conductivity of carbon materials, it is difficult for carbon-based epoxy to achieve the high thermal conductivity while obtaining desired dielectric property. In this article, using GNP and MWCNT modified by titanate coupling agent (PN-105), a novel method for highly thermally conductive, but electrically insulating epoxy nanocomposites is reported. The experimental results show that the 4% modified MWCNTs/epoxy nanocomposite has presented a simple thermal conductivity network, which can significantly improve the thermal conductivity of epoxy resin (EP), about 6.5 times higher than pure epoxy. Co-filled with 2% GNPs and 4% MWCNTs, the thermal conductivity of the epoxy nanocomposite is increased to 2.04 W/mK, 957% higher than pure epoxy. In addition, the dielectric constant of the composite is 9.1, which is maintained within an acceptable range. The dynamic mechanical results show that the filling of carbon materials can reduce the storage modulus and the loss factor of EP.

Polymer-based dielectric materials with high energy storage performance have become an important part of electric power and electronic systems. But due to the low intrinsic dielectric constant of polymers, it is usually needed to mingle high dielectric constant nanofillers to improve their dielectric properties. However, the addition of nanoparticles often results in higher dielectric loss and lower breakdown strength. Herein, using a simple method of surface modification of BaTiO3, silica and polydopamine are coated on the surface of BaTiO3, significantly improving the dielectric properties of the polymer. Meanwhile, the composite with a sandwich structure is prepared by using BaTiO3@SiO2@PDA/PVDF as the central layer and pure PVDF as the two outer layers, achieving an ultrahigh breakdown strength (633 MV/m). The sandwich-structured composite with 1 wt % BaTiO3@SiO2@PDA has the highest discharge energy density (15.4 J/cm3). The simulation results reveal that the sandwich structure not only acts as an interface carrier barrier but also optimizes the electric field concentration inside the composite, which reduces the probability of electric breakdown. This work can broaden the way for dielectric films to be used in the field of high energy density, and the modification strategy can also provide ideas for other fields.

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