高强度、超疏水聚对苯撑苯并二噁唑纳米透波复合纸 | Science Bulletin

聚对苯撑苯并二噁唑（PBO）纤维被誉为21世纪的超级纤维，其衍生的PBO纳米纤维（PNF）被视为制备高性能透波复合纸的理想原材料，在航空/航天、交通运输和5G通讯等领域具有广阔的应用前景。然而，PNF透波复合纸内的纳米纤维间的相互作用力较低，且PNF表面疏水性较差使其难以服役暴雨、冰雪、盐雾等恶劣自然环境。

西北工业大学化学与化工学院顾军渭教授“结构/功能高分子复合材料”（SFPC）课题组团队基于铁离子（Fe³⁺）与PNF表面N原子的配位作用在PNF间构建金属配位键获得预成型的三维互联纳米纤维网络，并通过溶胶-凝胶-薄膜转化法制备PNF纸；再在PNF纸表面喷涂聚四氟乙烯（PTFE）颗粒/P(S-co-BCB-co-MMA)混合溶液，经热交联制备双层结构PTFE-P/PNF纳米复合纸。

基于金属配位键和氢键的双重作用，PTFE-P/PNF纳米复合纸具有极佳的综合性能。当PTFE/P(S-co-BCB-co-MMA)的质量分数为50 wt%时，PTFE-P/PNF-50/50纳米复合纸具有最佳的韧性（16.4 MJ/m³）、出色的拉伸强度（271.6 MPa）和优异的耐折叠性能；介电常数（ε）和介电损耗正切值（tanδ）分别为2.06和0.0133，基于麦克斯韦方程建立的双层板透波模型计算出的电磁波从PTFE-P/PNF-50/50纳米复合纸两侧入射的透波率分别为97.6%（PNFs侧）和96.0%（PTFE/P(S-co-BCB-co-MMA)侧）。此外，PTFE-P/PNF-50/50纳米复合纸的PTFE/P(S-co-BCB-co-MMA)侧具有优异的超疏水（与水的接触角为151^o）和自清洁性能，且在强酸和强碱环境浸泡30天后仍具有稳定的超疏水性能。本工作研制的高强度、超疏水聚对苯撑苯并二噁唑纳米透波复合纸有望在航空/航天、交通运输和5G通讯的雷达天线罩、电磁窗等领域获得广泛的应用。

Fig. 1. Double-layered PTFE-P/PNF nanocomposite paper with high tensile strength and wave-transparent coefficient, super-hydrophobicity.

Fig. 2. Schematics of the Preparation for PTFE-P/PNF Nanocomposite Paper, and Exfoliation of PBO Fibers into PNFs. Schematics of the preparation for PTFE-P/PNF nanocomposite paper and exfoliation of PBO fibers into PNFs. Schematic diagram of the preparation for PTFE-P/PNF nanocomposite paper (a); process of converting PBO fibers into PNF/Fe₂(SO₄)₃ sol (b); TEM images of PNF (c, d); optical photographs of PNF gel with certain flexibility (e); SEM image showing the inside of the PNF gel (f); schematic diagram of the interaction mechanism between PNFs (g).

Fig. 3. Morphology of PNF, P/PNF and PTFE-P/PNF-50/50 nanocomposite paper. Optical photographs of PNF (a), P/PNF (d), and PTFE-P/PNF-50/50 nanocomposite (e) paper; SEM images of PNF (b), P/PNF (e), and PTFE-P/PNF-50/50 nanocomposite (h) paper; SEM images of fracture surfaces for PNF (c), P/PNF (f), and PTFE-P/PNF-50/50 nanocomposite (i) paper.

Fig. 4. Mechanical properties and folding resistance of PTFE-P/PNF-50/50 nanocomposite paper. Optical photographs of the PTFE-P/PNF-50/50 nanocomposite paper possessing ultraflexibility and withstanding a weight of 500 g (a); tensile stress-strain curves (b), tensile strength (c), modulus (d), and toughness (e) of the PNF, P/PNF and PTFE-P/PNF nanocomposite paper; tensile strength and toughness retention of the PTFE-P/PNF-50/50 nanocomposite paper after repetitive folding (f); schematic diagram of the mechanism of interactions between the PTFE/P(S-co-BCB-co-MMA) and the PNF paper for fabricating the PTFE-P/PNF nanocomposite paper (g); optical photographs of the PTFE-P/PNF-50/50 nanocomposite paper being continuously folded and unfolded, showing no breakage (h).

Fig. 5. Dielectric and wave-transparent performances of the PTFE–P/PNF nanocomposite paper. Dielectric constant ε (a), dielectric loss tangent tanδ (b), and wave-transparent coefficients |T|² of the wave-transparent model for a single-layer dielectric (c) of the PNF, P/PNF, and PTFE-P/PNF nanocomposite paper; wave-transparent model of a single-layer dielectric (d); diagram of electromagnetic wave transmission (e); wave-transparent model of a double-layered dielectric (f,g); |T|² values of the wave-transparent model for a double-layered dielectric with the incident surface being the PNF paper (h) and PTFE/P(S-co-BCB-co-MMA) layer (i).

Fig. 6. Hydrophobicity and self-cleaning properties of PTFE-P/PNF nanocomposite paper. Contact angles and AFM images of distilled water with PNF (a, a’), P/PNF (b, b’), and PTFE-P/PNF nanocomposite (c-f, c’-f’) paper; optical photographs of different liquids on the surface of the PNF paper (g) and PTFE-P/PNF-50/50 nanocomposite paper (h); representative contact process of a water droplet (5 μL) on the surface of the PTFE-P/PNF-50/50 nanocomposite paper with a sliding angle of about 11^o (i); self-cleaning process of the PNF paper (j), and the PTFE-P/PNF-50/50 nanocomposite paper (k) with dust as a mode of contaminant.

本研究工作得到了技术领域基金项目、凝固技术国家重点实验室（西北工业大学）开放课题（SKLSP202103）、高分子电磁功能材料陕西省“三秦学者”创新团队以及2021年度博士论文创新基金（CX2021036）的资助和支持。

论文信息：

Lin Tang, Yusheng Tang, Junliang Zhang, Yuhan Lin, Jie Kong, Kun Zhou* and Junwei Gu*. High-strength super-hydrophobic double-layered PBO nanofiber-polytetrafluoroethylenenanocomposite paper for high-performance wave-transparent applications. Science Bulletin, 2022, 67(21): 2196-2207

https://www.sciencedirect.com/science/article/pii/S2095927322004583

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作者简介： 

唐林，西北工业大学化学与化工学院，博士在读，研究方向为纤维增强聚合物基透波复合材料。

周琨，南洋理工大学，教授，主要从事材料力学与增材制造方面的研究。

顾军渭，西北工业大学化学与化工学院教授、博导，主要从事功能高分子复合材料和纤维增强先进树脂基复合材料的设计制备及加工研究。

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