1成果简介 

        随着全球能源危机和碳排放问题日益严峻，建筑节能、工业隔热和可穿戴热管理等领域的高效热绝缘材料需求急剧增长。理想的隔热材料应同时具备超低热导率、超轻质、良好的机械柔韧性和阻燃安全性。静电纺丝纳米纤维因其直径细（纳米级）、比表面积大、孔隙率高等特点，可有效限制空气对流和固体热传导，是制备高性能隔热材料的理想构筑单元。然而，传统静电纺丝主要制备二维纳米纤维膜，难以实现三维厚层隔热结构的快速、规模化构建；且单一聚合物纳米纤维的隔热性能和力学柔性往往难以兼顾。

        本文，东华大学丁彬教授团队在《ACS Applied Nano Materials》期刊发表题为"Lightweight PAN/TPU/Graphene Nanofiber Sponges via Solution Air-Assisted Electrospinning for Thermal Insulation"的研究论文。研究提出了一种溶液辅助气流静电纺丝新技术，以聚丙烯腈（PAN）和热塑性聚氨酯（TPU）为聚合物基体、石墨烯纳米片为功能填料，一步法快速构筑了三维轻质纳米纤维海绵（PAN/TPU/Graphene NFS）。

        该策略的核心创新在于：

        ①气流辅助显著提升纳米纤维的沉积效率和三维堆积能力，实现海绵的快速成型与可控厚度；

        ②PAN提供刚性骨架，赋予海绵结构稳定性和热稳定性；

        ③TPU提供弹性网络，赋予海绵优异的压缩回弹性和柔韧性；

        ④石墨烯纳米片在纤维中均匀分散，利用其超高比表面积和红外反射/散射效应，进一步阻断固态热传导和辐射热传递，协同降低热导率。

        所得纳米纤维海绵兼具超低热导率、超轻质、优异压缩回弹性和阻燃特性，在建筑隔热、管道保温、可穿戴热防护等领域展现出广阔应用前景。

        2图文导读  

        图 1. (a) Schematic illustration for PAN nanofibrous sponges. (b) PNFS on a fresh flower stamen. (c) Three-dimensional network structure fibers. (d) The curled single fiber under the scanning electron microscope. (e) A single fiber has a rough surface. (f-g) Mechanical representation of PNFS. (h) PNFS is placed on the heating plate. (i) Optical photos of the large-sized PNFS.

        图2. (a, b) Fiber structures of PNFS with different relative humidity. (c) Plots of the linearized cloud points for the PAN systems. (d) Cloud point curves representing the PAN system displayed in the ternary phase diagram. (e) Schematic illustration of the formation process of PAN aerogel fiber based on humidity-induced jet gelation. The average diameter(f), volume density and porosity (g) of fibers at different relative humidity levels. (h) The scanning electron microscope image and the actual image of PNFS-C at 90% relative humidity. (i) The volume density and porosity of aerogel with different graphene contents. (j) Pore size distribution. (k) BET surface area, and pore volume for PNFS.

        图3. (a) Tensile stress–strain curve of the PNFS and PAN. (b) Tensile stress versus strain curves of PNFS under different tensile strains. (c)Stress–strain curves of PNFS during an 800-cycle tensile fatigue test. (d) Compressive stress versus strain curves of PNFS under different compressive strains. (e) Stress–strain curves of PNFS during an 800-cycle compressive fatigue test. (f) Young’s modulus, energy loss coefficient, and maximum stress of the PNFS under different cycles. (g) The modulus and damping ratio of PNFS at different frequencies. (h) Modulus and damping ratio of PNFS for different cycle counts. (i) Compressive elasticity demonstration of PNFS in liquid nitrogen.

        图4. (a) Thermal conductivity and volume density of common three-dimensional thermal insulation materials. (b) Infrared thermal imaging pictures of different products on the palm. (c) Temperature comparison between simulated skin covered with PNFS-C and cotton. (d) Thermal conductivity versus volume density for PNFS and other warmth retention materials. (e) Thermal imaging images of the conversion of light energy to heat for different products under light exposure. (f) Image demonstrating antibacterial properties of PNFS and three other antibacterial materials.

        3小结 

        综上所述，本研究开发了一种具有辐射发热功能的轻质、卷曲且力学性能优良的纳米纤维保温海绵，该材料能够高效地转换光能和热能，从而实现多功能的保温和蓄热性能。在高湿度条件下进行静电/气流纺丝时，通过纺丝喷嘴诱导相分离，从而在纤维结构上实现了高孔隙率。石墨烯的掺入赋予了该材料更优异的光热转换功能和抗菌性能。在模拟日光条件下，其温度在5分钟内升至52.6 °C。与其他保温材料相比，PNFS-C的体积密度更低（4.01 mg cm–3），热导率为27.85 mW m–1K–1。此外，该材料还展现出优异的力学性能。重量仅为0.07克的海绵可轻松托起500克重物而不破裂，并在液氮环境（-196 °C）中表现出卓越的弹性。在经历800次拉伸和压缩循环后，其抗疲劳性能依然出色。与此同时，PNFS-C纳米海绵还具备抗菌性能和疏水性能等其他优异特性。这些结果表明，PNFS-C可能为下一代先进热管理材料的开发提供新的解决方案。

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