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In this work, Ni@GNP nanohybrids fabricated via an in situ reduction method were incorporated into polymethyl methacrylate (PMMA) to prepare PMMA/Ni@GNP nanocomposites via solution blending and hot-pressing. The Ni nanoparticles with an average diameter of 70–80 nm were observed to successfully grow on the GNP surface via SEM and TEM. Both thermally conductive and microwave absorbing properties of the prepared composites were intensively investigated. A reflection loss test experimentally suggested that the PMMA/Ni@GNP composites showed a good microwave absorbing property, among which the composite containing 30 wt % Ni@GNP displayed the best microwave absorption performance (with a value of −30 dB for RL min in the C band). The thermal conduction behavior of the composites was jointly studied by infrared thermal imaging (ITI) and enthalpy transformation method together with a four-parameter model. The average heating rate during an initial stage was obviously found to increase from 65.4 to 103.2 °C/min, indicating that a well-defined heat conduction network gradually formed in the composites, which exerted positive influence on heat conduction. The composites generally bore perfect thermal conductivities (e.g., with a maximum in-plane thermal conductivity of 9.02 W/m·K and a maximum out-of-plane value of 1.29 W/m·K), and the variations of thermal conductivity versus filler loading should be attributed to the construction of an anisotropically thermally conductive network in the composites. The PMMA/Ni@GNP composites with desirable microwave absorption and thermal conductivity would find potential applications in 5G communication devices.

In this research, series of PVDF microporous films with various polymer concentrations and thickness were prepared through thermally‐induced phase separation in air condition with diphenyl carbonate as the diluent. Effects of polymer concentration and film thickness on the formation kinetics of microporous structure of PVDF thin films were in situ investigated via TII technique. The instantaneous heat conduction inside the films during film formation was also evaluated. Two types of parameter models were adopted in order to disclose the time and location dependence of TIPS film solidification kinetics, respectively. Hierarchical microstructures, crystallization behavior and thermal properties of the TIPS films were also characterized by SEM, DSC, and TGA, respectively. The current study could supply an insight into the fabrication of PVDF microporous films with target microstructure and desirable performance.