1成果简介

　　随着先进电子设备向集成化与微型化方向发展，具备高效封装与热管理特性的相变材料（PCMs）变得至关重要。本文，西南交通大学祁晓东副教授、王勇教授、四川大学华西药学院林箐 副教授《ACS Sustainable Chem. Eng》期刊发表名为“Hierarchical Wood-Derived Carbon Scaffold with Layer-Pillar Structure Enabling Thermomechanical Stability and Bidirectional Thermal Conductivity in Phase Change Materials”的论文，研究受建筑框架结构启发，采用木质衍生的碳骨架（CW）作为“层”，原位生长的碳纳米管（CNTs）作为“柱”，成功构建出层-柱结构支架，命名为CW@Ni-CNTs。
　　该架构实现了聚乙二醇（PEG）的高效封装。所得复合相变材料（CW@Ni-CNTs/P）展现出卓越的热机械稳定性：在10牛顿载荷下保持94.3%的形状保持率，经多次热循环后渗漏率低于3%。互穿网络使轴向导热性提升160.87%，径向导热性提升143.48%，同时为PEG提供39.62 dB的电磁干扰（EMI）屏蔽效能。结合高潜热特性，该复合相变材料在电子设备中展现出稳定的热管理性能。这种分层柱状结构设计为制造兼具结构与功能特性的复合相变材料提供了有效策略。
　　2图文导读 

　　图1. Schematic of the preparation process and multifunctional application of CW@Ni-CNTs/P. (a) Procedure for the preparation of CW@Ni-CNTs/P. (b) Conceptual illustration of the multifunctional CW@Ni-CNTs/P, including thermomechanical stability, electromagnetic shielding, and thermal management properties.

　　图2. Microscopic morphologies of (a1-a2) NW, (b1-b2) DW; (c) digital photos and contact angles; (d) FTIR spectra, (e) XRD patterns, and (f) porosity of NW and DW.

　　图3. Microscopic morphologies of (a1, a2) CW@Ni-CNTs-700, (b1-, b2) CW@Ni-CNTs-800, and (c1, c2) CW@Ni-CNTs-900; (d, e) EDS mappings of CW@Ni-CNTs-700 at high magnification.

　　图4. (a) FTIR spectra, (b) XRD patterns, (c) XPS full spectra, (d) C 1s spectra, (e) N 1s spectra, (f) Ni spectra, (g) Raman mappings, and (h) average ID/IG of CW@Ni-CNTs.

　　图5. (a–c) Microscopic morphologies of CW@Ni-CNTs-700/P; (e–f) dimensional retention ratio curves during heating under constant pressure; (g) weight percentage (wt %) of PEG leaked from CW/P and CW@Ni-CNTs/P at 70 °C; and (h) schematic illustration showing the mechanisms for the improved thermomechanical stability.

　　图6. (a, b) DSC curves during cooling and heating processes; (c) latent heat values; and (d) phase change temperatures of samples. (e) Thermograms obtained from the multicycle DSC tests and (f) DSC data of CW@Ni-CNTs-900/P; (g) TGA curves of PEG and CW@Ni-CNTs/P; (h) XRD patterns; and (i) FTIR spectra of PEG, CW/P, and CW@Ni-CNTs/P.

　　图7. (a) Simulated transient heat flux distribution by finite element analysis; (b) simulated time–temperature curves at the top center of CW/P and CW@Ni-CNTs-700/P; and (c) schematic diagram of bidirectional heat transfer mechanism.

　　图8. (a) Schematic diagram and images of the device used to test thermal management performance; (b) time–temperature curves; (c) highest temperatures of LED at different output powers of samples; (d) T time–temperature curve in thermal shock cycling stability test of CW@Ni-CNTs-900/P⊥; and (e) schematic diagram of the multiple thermal management mechanism.
　　3小结
　　综上所述，本研究成功开发出具有层柱结构的木质基复合相变材料，显著提升了聚乙二醇（PEG）的热机械性能、双向导热性和电磁屏蔽性能。研究系统揭示了不同碳化温度对碳纳米管形态的调控作用。具体而言，木质碳框架提供了具有充足毛细力的微米级通道，而穿透这些层状结构的碳纳米管则形成纳米约束效应，确保熔融聚乙二醇的高效封装。所得CW@Ni-CNTs/P材料在100次热循环后仍保持优异的热机械稳定性（10牛顿载荷下形状保持率达94.3%）和稳定的相变特性。独特的层柱结构促进双向热传导平衡，轴向与径向导热系数分别达0.60 W·m⁻¹·K⁻¹和0.56 W·m⁻¹·K⁻¹。该结构还构建了连续导电网络，实现39.62 dB的电磁屏蔽效能。此外，该结构在反复吸热/放热循环中保持稳定的温度调控能力，展现出卓越的热冲击循环稳定性。这种仿生结构设计借鉴建筑原理，为开发适用于热能存储与利用领域的高性能相变材料提供了新思路。
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