Polyimide (PI) is widely used in the communication field benefited from its low dielectric properties and good electrical insulating properties, however, its low thermal conductivity simultaneously limits its application in electronic packaging. Delayed heat dissipation can exacerbate the thermal stress generated by device operation to damage electronic structures, thereby affecting work efficiency. As a result, it is necessary to improve the thermal conductivity of polyimide and maintain excellent dielectric performance. Here, we demonstrate the polyimide (BPDA‐ODA) composites with ordered structure are prepared by filling commercial polyimides with aramid nanofibers connection nitrides greatly improve thermal conductivity and maintain the low dielectric loss. When the filling amount of SBN@CN is 30 wt%, the thermal conductivity increases to 1.162 W/mK, which is 8 times higher than that of pure PI (0.0147 W/mK). Moreover, thermal stability and mechanical properties are maintained, realizing that the dielectric constant is about 3.81 and the dielectric loss is as low as 0.0034 at 100 MHz, which endows a new insight for the application of polyimide in electronic packaging.
The generation of cyclic carbonates by the cycloaddition of CO 2 with epoxides is attractive in the industry, by which CO 2 is efficiently used as C1 source. Herein, a series of catalysts were developed to efficient mediate the cycloaddition of CO 2 with epoxides to generate carbonates. The catalysts were easily synthesized via the amine-formaldehyde condensation of ethidium bromide with a variety of linkers. The newly prepared heterogeneous catalysts have high thermal stability and degradation temperatures. The surface of the catalysts is smooth and spherical in shape. The effect of temperature, pressure, reaction time and catalyst dosage on the cycloaddition of CO 2 with epoxide were investigated. The results show that the catalyst with 1,3,5-tris(4-formylphenyl)benzene as the linker can achieve 97.4 % conversion efficiency at the conditions of 100 °C, reaction time of 12 h, and the reaction pressure of 1.2 MPa in a solvent-free environment. Notably, the polymers serve as homogeneous catalysts during the reaction (reaction temperature above T g ) and can be separated and recovered easily as homogeneous catalysts at room temperature. In addition, the catalyst is not only suitable for a wide range of epoxide substrates, but also can be recycled many times. Furthermore, DFT calculations show that the coordination between the electrophilic center of the catalyst and the epoxide reduces the energy barrier, and the reaction mechanism is proposed based on the reaction kinetic studies and DFT calculations.
Preparation of polymer-based packaging materials with rapid heat dissipation capacity is crucial for ensuring highpower equipment's service life. To achieve this, boron nitride (BN) and multi-walled carbon nanotubes (MWCNTs) were used in different ratios to prepare thermally conductive epoxy composites. These composites were created through a simple mixing and curing process, resulting in a heat transmission path. Then, BN and MWCNTs were separately functionalized with dopamine and acid to enhance their dispersibility and interfacial compatibility within the epoxy resin. This was done to further explore their influence on the formation of serial heat transfer pathways. The BN/ MWCNTs/epoxy composites with a filler ratio of 15:1 and a total filler loading of 30 wt % exhibited a thermal conductivity of 0.92 W/mK, which is 118% higher than pure epoxy. These composites also displayed favorable mechanical properties and thermal stability. This study provides guidance for designing highperformance epoxy composites to meet modern electronic devices' thermal management requirements.
The conversion of CO2 into value-added chemicals has become an imminent research topic and the cycloaddition of CO2 with C1 resource to produce cyclic carbonates is an promising pathway for...
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