近期，青岛大学的特型非织造材料研究团队在此领域取得重要进展。团队2023级硕士生张硕、2022级纺织工程三位本科生汪钊、谢韬、冯志豪共同参与完成，相关研究成果以题目为“Porous core-shell PU composite membrane with AgNWs conductive network for electromagnetic shielding”的论文发表于《ACS Omega》期刊。

特型非织造材料研究团队开发同轴湿法纺丝技术，制备出断裂伸长率超1500%的多孔核-壳PU纤维长丝，纤维内部富含多级多孔结构，为电磁波吸收与导电网络构建提供理想载体。通过多元醇法合成直径约100 nm的银纳米线（AgNWs），结合真空辅助过滤与热粘合工艺，利用PU纳米纤维自粘作用，将AgNWs功能层与PU纤维基底牢固结合，成功制备出一种具有优异机械柔韧性和稳定电磁屏蔽性能的多孔核壳结构聚氨酯（PU）复合膜，该材料不仅屏蔽效能优异，更在成本控制、环保（低反射）和机械稳定性方面展现出独特优势，为可穿戴设备、柔性电子封装等领域的电磁防护提供了新材料解决方案。研究结果显示，AgNWs在复合膜表面均匀分布，形成典型Janus双面结构：一侧为AgNWs导电层，一侧为多孔PU纤维层。在膜基底层中聚氨酯纤维的量被固定在500毫克时，样品拉伸应力达0.73 MPa，断裂应变高达247.68%，在10%形变下仍保持结构完整，完美适配柔性与可变形使用场景。

研究亮点：

1．制备工艺创新且简便：开发同轴湿法纺丝技术，一步法制备出兼具多孔与核-壳结构的PU纤维骨架，无需二次造孔，工艺简单高效。

2．显著的成本控制策略：研究提出了一种新颖的性能调控思路，即在固定最低银纳米线用量（6 mg）的前提下，通过增加廉价PU基底的厚度，即可大幅提升屏蔽效能。例如，将PU基底从300 mg增至700 mg，屏蔽效能从15 dB提升至29 dB以上，增幅近90%，为低成本高性能柔性屏蔽材料的开发提供了新路径。

3．有效降低二次电磁污染：该复合膜具有独特的Janus结构。当电磁波从纯PU面入射时，低导电性的PU层减少了表面反射，使电磁波更多进入材料内部，在银纳米线构建的三维导电网络和多孔结构中经历多次反射和吸收而被耗散。测试表明，其吸收损耗占比高达总屏蔽效能的92.1%，实现了以吸收为主的屏蔽机制，极大降低了电磁波反射造成的二次污染。

4．卓越的力学与屏蔽稳定性：基于PU本身优异的弹性（纤维伸长率超1500%），该复合膜具备极好的柔韧性和可拉伸性。在承受10%的拉伸形变时，其电磁屏蔽效能仍能保持在高水平（最高可达29.24 dB），证明了其在动态弯曲、拉伸环境下应用的可靠性。

Fig.1 (a) Schematic diagram of porous core-shell PU fibers prepared by coaxial wet spinning; (b,c) cross-section image of core-shell PU fiber; (d,e) longitudinal section of core-shell PU fiber; (f) FTIR spectrum of PU fiber; (g) Stress-strain curve of PU fiber; (h) Demonstration of fiber elasticity and photographs of the fibers; (i) SEM images of AgNWs; (j) Diameter statistics of AgNWs. 

Fig.2 (a) Schematic process of PU/AgNWs electromagnetic shielding membrane; (b,c) SEM images of PU layer surface of the composite membrane; (d,e) SEM images of AgNWs layer surface of the composite membrane; (f,g) SEM images of the composite membrane cross-section; (h,i) Stress-strain curves of composite membrane; (j) XRD pattern of AgNWs layer of the composite membrane. 

Fig.3 (a) Electromagnetic interference (EMI) shielding effectiveness of composite membranes with a fixed 500 mg PU fiber and different AgNWs contents; (b) Reflection shielding effectiveness (SER) and absorption shielding effectiveness (SEA) of composite membranes with different AgNWs contents incident from Side A; (c) SER and SEA of composite membranes with different AgNWs contents incident from Side B; (d) EMI shielding effectiveness of composite membranes with a fixed 6 mg AgNWs content and different PU fiber contents; (e) SER and SEA of composite membranes with different PU fiber contents incident from Side A; (f) SER and SEA of composite membranes with different PU fiber contents incident from Side B; (g) Schematic diagram of the electromagnetic shielding mechanism of the composite membrane. 

Fig. 4 For composite membrane, PU fiber content is fixed at 500 mg with different AgNWs contents: (a-b) SET, SEA and SER of composite membrane before and after 10% stretching deformation incident from Side A; (c-d) SET, SEA and SER of composite membrane before and after 10% stretching deformation incident from Side B. AgNWs content is fixed at 6 mg with different PU fiber contents: (e-f) SET, SEA and SER of composite membrane before and after 10% stretching deformation incident from Side A; (g-h) SET, SEA and SER of composite membrane before and after 10% stretching deformation incident from Side B. 

Fig.5 Average values of R and A, composite membrane with 500 mg PU fibers and different AgNWs contents: (a) without stretching, electromagnetic wave incident from side A; (b) without stretching, electromagnetic wave incident from side B; (c) stretched by 10%, electromagnetic wave incident from side A; (d) stretched by 10%, electromagnetic wave incident from side B. Composite membrane with 6 mg AgNWs and different PU fiber contents: (e) without stretching, electromagnetic wave incident from side A; (f) without stretching, electromagnetic wave incident from side B; (g) stretched by 10%, electromagnetic wave incident from side A; (h) stretched by 10%, electromagnetic wave incident from side B. 

团队与背景

该研究由青岛大学纺织服装学院、非织造材料与产业用纺织品创新研究院、特型非织造材料山东省工程研究中心明津法教授团队完成，课题组2023级硕士生张硕为论文第一作者，2022级纺织工程三位本科生汪钊、谢韬、冯志豪共同参与，明津法老师为通讯作者。明津法教授团队长期致力于特型非织造材料与产业用纺织品、功能纤维纤维等研究，先后在Advanced Industrial and Engineering Polymer Research、Applied Materials Today、Journal of Hazardous Materials、International Journal of Biological Macromolecules、ACS Applied Materials & Interfaces、Sustainable Materials and Technologies、ACS Omega等期刊发表系列研究论文，聚焦于辐射制冷、隔热保温、空气过滤、防冰/除冰、抗菌等领域。

论文链接：

http://doi.org/10.1021/acsomega.6c01503 

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