Flexible and conductive polyurethane composites for electromagnetic shielding and printable circuit

Abstract

With recent emergence of portable and wearable electronics, it is imperative to design a novel electromagnetic interference (EMI) shielding material which possesses flexibility, ultra-thinness and excellent EMI shielding effectiveness (SE) to prevent the adverse effect of electromagnetic radiation. Herein, we fabricate the ultrathin and flexible four corners needle zinc oxide whiskers/silver/waterborne polyurethane (T-ZnO/Ag/WPU) conductive films to realize different EMI shielding demand by tuning the nanofiller dispersion morphology. The T-ZnO/Ag/WPU composite film with uniform structure (prepared by blade coating method) shows excellent flexibility and EMI SE of over 42 dB at a thickness of only 0.02 mm. Highly reliable shielding ability is achieved with 92% EMI SE retention after 1000 folding cycle tests. The T-ZnO/Ag/WPU composite film with deposited layer structure (prepared by casting method) exhibits an ultrahigh EMI SE of over 87 dB at a thickness of 0.25 mm. At the same time, the T-ZnO/Ag/WPU composite shows great potential in printable circuit. The ultrathin and flexible T-ZnO/Ag/WPU composite films with excellent EMI SE are highly promising for applications in next-generation flexible electronics, especially the portable and wearable electronic devices.