Sandwich-structured polyacrylate composite films for electromagnetic interference shielding with low reflection characteristics

The sandwich-structured polyacrylate composite films containing carbon nanotubes (CNTs) and magnetic fillers (Ni or Fe3O4) were prepared by spray coating and LBL-casting. CNTs were uniformly distributed in polyacrylate (PEA) matrix to prepare middle layer and magnetic fillers exhibited good distribution in PEA matrix as outer layer to reduce the secondary electromagnetic radiation pollution. The average electromagnetic interference shielding effectiveness (EMI SE) owns the highest value of 38.2 dB in 6-Fe3O4/MWCNT/6-Fe3O4 film, and the absorption coefficient (A) of the film account for about 0.56. The results indicated that this film shows absorption-dominated EMI shielding properties. It is mainly attributed to sandwich structure of the composite film, synergistic electric/magnetic losses and polarization relaxation loss to further attenuate electromagnetic wave. The microwave can undergo a unique “absorb-reflect-reabsorb” process. Therefore, polyacrylate composite films with low reflection and high EMI shielding can be used in small-scale and sophisticated electronic devices.