Nanocellulose-Assisted Lightweight Nanostructured Aerogels with Orientated Biomimetic Cell Walls for High-Performance Electromagnetic Interference

Lightweight nanostructured aerogels have attracted more and more attention for addressing emergency electromagnetic radiation or interference thanks to their high and controllable electromagnetic interference (EMI) shielding performances arising from cellular structure and nanoscale building blocks thereof including their synergistic interactions. Efficient design and utilization of cellular morphologies and functional nanomaterials for higher EMI shielding effectiveness (SE) at lower material consumption is always the research trend yet remains challenging. Here, we employed thin-dimension cellulose nanofibrils (CNFs) for assisting in building ultralow-density, robust, and highly flexible nanostructured aerogels with orientated biomimetic hybrid cell walls. The ultrathin cell walls with conductive nanomaterial including carbon nanotubes, AgNWs, and MXene as “bricks” bonded by nanoscale CNF “mortar” maintain high electrical conductivity of pristine nanomaterials and enhance significantly the mechanical strength of hybrid aerogels. High conductivity and introduced interfaces between nanomaterials and CNFs lead to high intrinsic shielding ability of cell walls, which can be amplified by the cellular structures in the aerogels. Particularly, a significant influence of angles between cell walls' orientated direction and electric field direction of incident EM waves on EMI shielding performance is displayed. This provides an intriguing and crucial concept for controlling EMI shielding performance based on the microstructural design strategy in EMI shielding applications. Taking complete advantage of the biomimetic cell walls and cellular structure, EMI SE of the MXene/CNF hybrid aerogels can reach as high as 74.6 or 35.5 dB at densities of merely 8.0 or 1.5 mg/cm3, respectively. The normalized surface-specific SE (defined as the SE divided by the material density and thickness) are up to 189400 dB·cm2/g, which significantly exceeding that of other EMI shielding materials reported so far. This work thus suggests a convenient, facile, low-cost, and scalable preparation approach for constructing high-performance porous macrostructures with potential applications in next-generation lightweight, flexible electronic devices and aerospace. Biography Zhihui, Zeng. Professor, Dr. Professor Zhihui Zeng currently works in the School of Materials Science and Engineering, Shandong University (SDU), Jinan, China. He received his Ph.D. degree in 2016 from the National Center for Nanoscience and Technology (NCNST), University of Chinese Academy of Sciences, Beijing, China. After obtaining the Ph.D. degree, he worked as a postdoctoral research fellow at Nanyang Technological University, Singapore (2016-2018) and in the Cellulose & Wood Materials Lab at Empa- Swiss Federal Laboratories for Materials Science and Technology, Switzerland (2018-2021). Till now, he has published ~40 papers including Adv. Mater., Adv. Funct. Mater. Adv. Sci., ACS Nano, Small, etc. with an h index of 20. His research interests include the design, fabrication, and application of multi-functional polymer-based nanocomposites, nanostructured assemblies, and cellular materials