Hierarchically Structured\nCellulose Acetate@Silk Protein\nMembrane with Enhanced Mechanical and Electromagnetic Interference\nShielding Performances

Compared to conventional fibers, electrospun porous nanofibers\nwith hierarchical structures often involve additional active sites,\ninterfaces, and internal spaces which boost the performances of functional\nmaterials. Here in this study, coaxial composite cellulose acetate@silk\nfibroin (CA@SF) fibrous membranes are constructed through an electrostatic\nspinning technique combining solvent-induced phase separation. Hierarchical\ncore–shell structures on the fibers are achieved, which significantly\nincreases the surface area and benefits the mechanical property, flux,\nas well as the electroless deposition of Ag nanoparticles. The total\nelectromagnetic shielding efficiency of the sandwiched hierarchical\nCA@SF@Ag composite membrane with a thickness of only 100 μm\nreaches up to 100 dB, surpassing around 82% beyond nonhierarchical\nones. To be noticed, when post-treated by ethanol, the membrane enables\nan enhanced tensile strength of up to 10 MPa with a thickness of only\n50 μm. Our findings pave the way to the application of electrospun\nfiber membranes in the field of ultrathin electromagnetic shielding\nfilms.