Kun Zheng

Developing polymer composites with simultaneous high thermal conductivity and mechanical integrity remains challenging due to interfacial phonon scattering and the filler‐loading trade‐off. Herein, a hierarchical “dual‐ordering” strategy is proposed to construct high‐performance structural‐functional integrated materials by synergizing a thermotropic liquid crystalline phthalonitrile (LCPN) matrix with cyanobiphenyl‐based mesogen‐functionalized graphene (CBN‐G). This strategy operates on two synergistic levels: the in situ locking of nematic liquid crystalline domains within the matrix and the construction of a covalent “phonon‐matching” gradient interface. The pristine resin matrix thereby achieves a high intrinsic in‐plane thermal conductivity of 0.71 W m ^{− 1} K ^{− 1} . Crucially, the interfacial ordering is theoretically validated by non‐equilibrium molecular dynamics (NEMD) simulations to reduce interfacial thermal resistance by ∼79% via enhanced vibrational resonance. Consequently, the resulting composite delivers an exceptional in‐plane thermal conductivity of 6.55 W m ^{− 1} K ^{− 1} at a low loading of 10 wt.%. Furthermore, the robust covalent bridging transforms the failure mechanism from adhesive to cohesive, boosting the flexural strength to 123 MPa—an improvement of 89% over physically blended counterparts. This work not only elucidates the atomic‐scale mechanism of interfacial phonon transport but also establishes a versatile engineering paradigm for next‐generation thermal management systems in extreme environments.

Simultaneously improving the processability and heat resistance for bismaleimide (BMI) resins remains an open challenge. Herein, the processing performance of traditional BMIs with high melting points, including m-phenylene bismaleimide (MPD-BMI), 3,3'-diphenylsulfone bismaleimide (33DDS-BMI) and bisphenol A bismaleimide (BDM), is significantly improved by forming eutectic systems though blending with low-melting-point BMI monomers, indan bismaleimide (PIDA-BMI) and aliphatic bismaleimide trimethylhexane bismaleimide (SEM23). The results show that modification of the 33DDS-BMI system with PIDA-BMI yields a remarkable 60% reduction in melting point, coupled with a 6% increase in glass transition temperature (Tg), when compared to the unmodified 33DDS-BMI system. Similarly, compared with pure BDM, the SEM23/BDM system shows a 14% lower melting point, while its Tg and the flexural strength increases by13% and 10% respectively. Mechanistic analysis reveals that introducing low-melting-point BMI monomers forms a eutectic system, inducing amorphization of polycrystalline states via inherent structural differences in BMI monomers. This reduces resin crystallinity and enhances segmental mobility, thereby synergistically optimizing melting point, heat resistance, and mechanical properties. This work provides a strategy for simultaneously enhancing processability and heat resistance for BMI resins.

Simultaneously improving the processability and heat resistance for bismaleimide (BMI) resins remains an open challenge. Herein, the processing performance of traditional BMIs with high melting points, including m-phenylene bismaleimide (MPD-BMI), 3,3'-diphenylsulfone bismaleimide (33DDS-BMI) and bisphenol A bismaleimide (BDM), is significantly improved by forming eutectic systems though blending with low-melting-point BMI monomers, indan bismaleimide (PIDA-BMI) and aliphatic bismaleimide trimethylhexane bismaleimide (SEM23). The results show that, after PIDA-BMI modified 33DDS-BMI systems, the melting point decreases as high as 60% and the glass transition temperature (Tg) increases by 6%, compared with 33DDS-BMI systems. Similarly, for SEM23/BDM system, the melting point decreases by 14%, Tg increasesand and the flexural strength increases by by 13% and 10% respectively, compared with pure BDM system. Mechanistic analysis reveals that introducing low-melting-point BMI monomers forms a eutectic system, inducing amorphization of polycrystalline states through BMI structural differences. This reduces resin crystallinity and enhances segmental mobility, thereby synergistically optimizing melting point, heat resistance, and mechanical properties. This work provides a strategy for simultaneously enhancing processability and heat resistance for BMI resins.

The electromagnetic wave (EMW) absorption at low‐frequency range of a material is constrained by the Snock limit due to its low natural resonance frequency ( f _r ). Herein, we develop a nitrogen‐doped hollow soft‐magnetic alloy coated carbon composites (CoNi@NC) by enhancement of f _r and optimization of impedance matching to break through the Snock limit, fulfilling an EMW absorption in n77 (3.3–4.2 GHz), n78 (3.3–3.8 GHz), and n79 (4.4–5.0 GHz) of the whole 5G bands. The multiple heterogeneous interfaces in our composites are constructed to regulate their dielectric loss ( ε′′ ), and defect engineering is designed to control magnetic loss ( µ′′ ) for the formation of a magnetic‐dielectric synergistic loss system, which significantly enhances the f _r and optimizes the impedance matching. Ultimately, it achieves a superior reflection loss of −47.66 dB and a low‐frequency effective absorption bandwidth of 2.21 GHz (2.95–5.16 GHz). Density functional theory calculations reveal that nitrogen atoms could gather electrons at the Fermi level of material and form an asymmetric structure, as well as influence magnetic domains, resulting in a 180% increase in µ′′ of CoNi@NC compared to pure CoNi. This work offers a strategy for preparation of multi‐functional materials to realize EMW absorption application in 5G Terminal.

Boron nitride nanosheets (BNNS) are expected to be ideal fillers because of their high thermal conductivity and excellent electrical insulation. However, it is still an open challenge to produce BNNS on a large scale using ecofriendly solvents. Here, first, we demonstrate an effective liquid exfoliation method for producing BNNS via utilizing deep eutectic solvents (DES) composed of D,L-menthol and various acids with the assistance of ultrasonication. The results show that the BNNSs with sizes of 1-2 mu m in width and 6-8 nm in thickness were successfully exfoliated with a DES formulation of D,L-menthol and decanoic acid. Second, the obtained BNNSs were used for fabricating 1,6-hexanediol diacrylate@polydopamine functionalized BNNS (HDDA@BNNSs-PDA) core-shell microspheres via a Pickering emulsion method. Furthermore, these microspheres were incorporated into a polyvinylidene fluoride (PVDF) matrix to construct 3D thermally conductive networks, leading to a substantial enhancement in the thermal conductivity of the resulting composites. Impressively, the composites with only 25 wt % of BNNS loading reach a high thermal conductivity of 3.20 W/m K, which is a 1500% increase over the pure polymer matrix. This work not only provides a significant way for producing BNNSs ecofriendly but also demonstrates a tactic for constructing 3D thermally conductive networks.