Kai Wu

Efficient thermal management and reliable interfacial adhesion remain challenging for high‐power, high‐frequency copper‐clad laminates (CCLs) due to the intrinsic trade‐off between thermal conductivity and bonding strength in conventional polymer composites. Here, a functional‐gradient sandwich architecture polytetrafluoroethylene (PTFE) based CCL is developed to decouple heat transport and interfacial bonding. The laminate consists of a central thermal conductive (TC) layer and two adhesive layers. The proposed architecture introduces synergistic functional regions with tailored filler networks. Large spherical boron nitride (SBN) particles construct interconnected three‐dimensional thermal pathways in TC layer, whereas hybrid small sized hexagonal boron nitride (hBN) and silicon nitride (Si ₃ N ₄ ) fillers are incorporated into the adhesive layers to enhance mechanical interlocking with copper foils and preserve certain thermal transport capability. Meanwhile, the low‐polarity PTFE matrix and electrically insulating ceramic fillers with optimized compositions maintain the intrinsic dielectric stability. In addition, a thickness‐dependent thermal transport model is established to correlate effective thermal conductivity with the relative layer thickness. The optimized sandwich CCLs achieve high thermal conductivity (3.96 W/m K), strong peel strength (1.5 N/mm), and ultralow dielectric loss (<0.0005), providing a general structural strategy to overcome the intrinsic trade‐off between thermal transport, interfacial adhesion and dielectric reliability in polymer‐based electronic substrates.

Polyethylene represents an exceptional thermal conductor in theory: The perfectly extended chain is predicted to conduct heat extremely well. However, its practical scalable forms fall far below this limit because noncrystalline structures disrupt heat transport across multiple length scales. Here, we identify that a partially ordered, noncrystalline transitional phase in highly aligned polyethylene is not a negative by-product of processing but a key contributor to heat conduction. Guided by this insight, we develop a gel-state intermittent slow stretching method that directs noncrystalline evolution during polyethylene fiber formation. This approach enables chain relaxation and structural reorganization in regions typically regarded as amorphous and interfacial, promoting their conversion into the transitional phase and their seamless integration with crystalline domains. The resulting structure extends the continuity of ordered shish segments within the period structure, increasing the distance over which heat can travel quasi-ballistically. As a result, polyethylene fibers with 26.79% noncrystalline content achieve thermal conductivities up to 70.61 watts per meter per kelvin, representing 1.45 to 2.60 times of leading commercial polyethylene fibers. These findings establish control of noncrystalline structure as an essential route to unlocking high thermal conductivity in polymers and open a pathway toward lightweight, fully organic thermal conductors.

Sorption-based atmospheric water harvesting (AWH) offers a decentralized, sustainable solution to global freshwater scarcity, enabling clean water in diverse environments. However, translating ideal sorption properties of small-scale materials into practical, large-scale systems faces critical kinetic challenges. Here, we conceptualize a hierarchical textile fiber for wearable AWH, addressing the scaling limitations of traditional sorbents. These fibers feature an open-pore surface topology and internal hierarchical pore structures, which accelerate surface vapor liquefaction and subsequent water transport, demonstrating exceptional water uptake and rapid sorption kinetics across varying relative humidity (RH). When woven into textiles, the fibers maintain efficient vapor diffusion through their macroporous, breathable architecture, achieving a 3- to 10-fold improvement over traditional sorbents at scale. We engineered a wearable prototype combining the AWH textile with a portable collector, achieving 3.76 to 7.45 liters _water per kilogram _sorbent per day and collecting 410 to 894 milliliters across 20 to 80% RH. By overcoming kinetic limitations, our study advances AWH toward scalability and wearability with implications for global water sustainability.

Current technologies for synergistically controlling the low dielectric constant and high thermal conductivity of polymer dielectrics struggle to improve signal transmission quality and heat accumulation issues without compromising material processability. This presents a persistent technical barrier to material innovation in electronics, power systems, and new energy applications. Herein, a double‐layer heterogeneous polyimide (PI) composite film with organic fiber (poly (p‐phenylene‐2, 6‐benzobisoxazole), PBO) is prepared by layered casting and encapsulation process. The ordered “chain network” within the PBO nanofilm and the well phonon matching characteristics with PI facilitate efficient phonon collisions, providing high‐speed pathways for phonon transmission. The 0.10 PNF//IL‐PI film exhibits excellent in‐plane thermal conductivity (λ _// = 17.95 W∙m ⁻¹ ∙K ⁻¹ ) and lower dielectric properties ( k = 2.68, tanδ = 0.008 at 10 ⁶ Hz). Furthermore, it has been fully demonstrated that the film can be used as a patch antenna substrate for high‐quality signal transmission, with a reflection loss intensity of only 4%. Therefore, this design strategy opens new horizons for the development of polymer dielectric materials for cross‐disciplinary integrated applications and provides novel insights for the advancement of high‐frequency flexible electronics.

Thermal interface materials (TIMs) based on liquid‐metal combine high thermal conductivity and conformability, but low mechanical strength and poor stability under dynamic loading limit their use. Here we employ an ultrathin porous polymer film, featuring a robust network with 100 nm nanopores for nanoscale confinement, as a structural scaffold to fix liquid‐metal like gel. Sputtered‐metal particles on the surface of the polymer film improve wetting and compatibility, enabling uniform infiltration and stabilization of liquid metal. The resulting metal–like gels reach a tensile strength of 117 MPa, the highest reported for TIMs, while retaining good flexibility. They can be made as ultrathin liquid‐metal gel films (≤2 µm), yielding ultralow bond‐line thickness and an interfacial thermal resistance of 6.1 mm ² ·K·W ^{− 1} at 80 psi. Excellent stability against pressure, folding, solvent exposure, and thermal cycling addresses key reliability barriers for advanced cooling applications.

Existing models of thermal conductivity in polymer composites typically address dilute to semi-dilute filler concentrations (≤ 40 vol%) yet fail to capture the strong interactions that arise when fillers are closely packed. In densely filled systems, these interactions reorganize heat transport according to the principles of thermal resistance, directing it along preferred pathways. In this study, we introduce a mechanistic thermal conductivity model based on a simplified body-centered cubic framework. This model effectively captures the essential impact of reduced interparticle distances and enhanced filler interactions in densely packed composites, enabling a more accurate description of heat flow by forcing it to follow the least-resistance pathways. This approach delivers high-precision predictions across a wide range of filler concentrations (0-68 vol%), spanning nearly the entire practical concentration range, and has been rigorously validated against diverse cross-material datasets. This model also can help to offer a physical interpretation of the thermal percolation transition, identifying both its underlying mechanism and the quantitative conditions for its onset. Its modular and computationally efficient design reduces reliance on extensive experimental testing, providing both a practical tool for optimizing composite design and a deeper quantitative understanding of thermal transport in composite materials.

Liquid metal-based thermal interface materials offer exceptional thermal conductivity and conformability, yet their low strength and stabilities remain huge challenges, which largely limits their applications under working conditions of dynamic loading. Here, we utilize an ultrathin nanofiber polymer film as a structural scaffold, which features a robust network essential for effectively confining liquid metal, resulting in unique interpenetrating metal-gel. Surface modification of polymer film with sputtered metals enhances compatibility, enabling uniform infiltration and stabilization of liquid metal. The obtained metal-gels exhibit a remarkable tensile strength of 117 MPa, the highest reported for thermal interface materials, while maintaining good flexibility. They can be fabricated as ultrathin films (≤ 2 µm), delivering an ultralow bond line thickness and interfacial thermal resistance (7.7 mm²·K·W⁻¹). With impressive stability against pressure, folding, solvent exposure, and cooling cycling, this work overcomes key reliability issues of liquid metal, offering promise for advanced cooling applications.