Soft and Damping Thermal Interface Materials with Honeycomb-Board-Mimetic Filler Network for Electronic Heat Dissipation.

High-power-density electronic devices under vibrations call for soft and damping thermal interface materials (TIMs) for efficient heat dissipation. However, integrating low hardness, high damping, and superior heat transfer capability into one TIM is highly challenging. Herein, soft, damping, and thermally conductive TIMs are designed and prepared by constructing a honeycomb-board-mimetic boron nitride nanosheet (BNNS) network in a dynamic polyimine via one-step horizontal centrifugal casting. The unique filler network makes the TIMs perform a high through-plane thermal conductivity (> 7.69 W m-1 K-1) and a uniform heat transfer process. Meanwhile, the hierarchical dynamic bonding of the polyimine endows the TIMs with low compressive strength (2.16 MPa at 20% strain) and excellent damping performance (tan δ > ≈0.3 at 10-2-102 Hz). The resulting TIMs also exhibit electrical insulation and remarkable recycling ability. Compared with the commercial ones, the TIMs provide better heat dissipation (4.1 °C) for a high-power 5G base station and less temperature fluctuation (1.8 °C) for an automotive insulated gate bipolar transistor (IGBT) under vibrations. This rational design offers a viable approach to prepare soft and damping TIMs for effective heat dissipation of high-power-density electronic devices under vibrations.

Revisiting the trapping of noble gases (He-Kr) by the triatomic H3+ and Li3+ species: a density functional reactivity theory study.

Small atomic clusters with exotic stability, bonding, aromaticity, and reactivity properties can be made use of for various purposes. In this work, we revisit the trapping of noble gas atoms (He-Kr) by the triatomic H3+ and Li3+ species by using some analytical tools from density functional theory, conceptual density functional theory, and the information-theoretic approach. Our results showcase that though similar in geometry, H3+ and Li3+ exhibit markedly different behavior in bonding, aromaticity, and reactivity properties after the addition of noble gas atoms. Moreover, the exchange-correlation interaction and steric effect are key energy components in stabilizing the clusters. This study also finds that the origin of the molecular stability of these species is due to the spatial delocalization of the electron density distribution. Our work provides an additional arsenal towards a better understanding of small atomic clusters capturing noble gases.

Toward Density-Based and Simultaneous Description of Chemical Bonding and Noncovalent Interactions with Pauli Energy.

Chemical bonds and noncovalent interactions are extraordinarily important concepts in chemistry and beyond. Using density-based quantities to describe them has a long history in the literature, yet none can satisfactorily describe the entire spectrum of interactions from strong chemical bonds to weak van der Waals forces. In this work, employing Pauli energy as the theoretical foundation, we fill in that knowledge gap. Our results show that the newly established density-based index can describe single and multiple covalent bonds, ionic bonds, metallic bonds, and different kinds of noncovalent interactions, all with unique and readily identifiable signature shapes. Two new descriptors, BNI (bonding and noncovalent interaction) index and USI (ultra-strong interaction) index, have been introduced in this work. Together with NCI (noncovalent interaction) and SCI (strong covalent interaction) indexes already available in the literature, a density-based description of both chemical bonds and noncovalent interactions is accomplished.