Wang Simin, Xiu Huijuan, Yin Dingwen, Li Jinbao, Liu Gengmei, Qin Yuxin, Hua Feiguo, Meng Qingjun, Wu Minzhe, Shen Mengxia
College of Bioresources Chemical & Materials Engineering, Shaanxi University of Science & Technology, Xi'an, Shaanxi 710021, China.
National Demonstration Center for Experimental Light Chemistry Engineering Education, Shaanxi Provincial Key Laboratory of Papermaking Technology and Specialty Paper Development, Xìan, Shaanxi 710021, China.
ACS Appl Mater Interfaces. 2025 Jan 8;17(1):2304-2316. doi: 10.1021/acsami.4c18237. Epub 2024 Dec 26.
Achieving high shielding effectiveness in electromagnetic shielding materials relies heavily on high conductivity, yet simultaneously enhancing the absorption loss remains a persistent challenge. Consequently, the study successfully creates efficient electromagnetic shielding composite films with a unique grape-like bunch structure of hollow nanosilver (HCAF) through layer-by-layer assembly. The utilization of poly(dopamine) (PDA) to anchor nanosilver granules (AgNPs) onto cellulose nanofibers (CNF) results in the formation of CNF@PDA@AgNPs. Subsequently, a surface protection etching method is employed to etch the AgNPs, resulting in hollow nanosilver (H-AgNPs) and the generation of CNF@PDA@H-AgNPs. A composite film featuring a grape bunch structure is fabricated by interweaving high aspect ratio CNF with CNF@PDA@H-AgNPs. A substantial quantity of H-AgNPs creates an abundant interface, while the grape bunch structure establishes an efficient conductive network. That enables the composite film to exhibit excellent impedance matching, excellent conductivity loss, abundant polarization loss, and multiple reflection loss. Therefore, the conductivity of the composite film with a thickness of 148.8 μm reaches 212660 S/m, with SE, SE, and SE 89.56, 79.03, and 10.53 dB in the X band, significantly better than the 76.9, 55.55, and 21.41 dB of the solid AgNPs composite film. The composite film also exhibits remarkable thermal conductivity (The coefficients of in-plane and out-plane thermal conductivity are 4.61 and 0.17 W/(m·K), respectively), mechanical properties, and strain sensing capabilities, making it significant potential for applications in flexible electronics and other related fields.
在电磁屏蔽材料中实现高屏蔽效能在很大程度上依赖于高导电性，但同时提高吸收损耗仍然是一个长期存在的挑战。因此，该研究通过层层组装成功制备了具有独特葡萄串状中空纳米银结构（HCAF）的高效电磁屏蔽复合薄膜。利用聚多巴胺（PDA）将纳米银颗粒（AgNPs）锚定在纤维素纳米纤维（CNF）上，形成CNF@PDA@AgNPs。随后，采用表面保护蚀刻法蚀刻AgNPs，得到中空纳米银（H-AgNPs）并生成CNF@PDA@H-AgNPs。通过将高长径比的CNF与CNF@PDA@H-AgNPs交织制备出具有葡萄串结构的复合薄膜。大量的H-AgNPs形成了丰富的界面，而葡萄串结构建立了高效的导电网络。这使得复合薄膜表现出优异的阻抗匹配、出色的传导损耗、丰富的极化损耗和多重反射损耗。因此，厚度为148.8μm的复合薄膜的电导率达到212660 S/m，在X波段的SE、SE和SE分别为89.56、79.03和10.53 dB，明显优于固体AgNPs复合薄膜的76.9、55.55和21.41 dB。该复合薄膜还表现出显著的热导率（面内和面外热导率系数分别为4.61和0.17 W/(m·K)）、机械性能和应变传感能力，在柔性电子和其他相关领域具有巨大的应用潜力。
