Three in one: A high tensile/nano mechanical nature, thermal conductivity, and green electromagnetic interference EMI shielding properties of polyvinyl alcohol/reduced-graphene oxide/iron hydroxide (PVA/rGO/ α-FeOOH) nanocomposite films

Nowadays, polymer composites-based electromagnetic interference (EMI) shielding materials play a crucial role in military, healthcare, telecommunications, and electronics. Particularly, polymer/reduced-graphene oxide (rGO) composites-based EMI shielding materials have captured great much attention nowadays due to their brilliant electrical and thermal conductivities. However, the strong interactions between rGO's layers ease the aggregation of rGOs, producing a side-effect on their electrical conductivity, thermal conductivity, mechanical behavior and EMI shielding properties representing a great challenge until now. Accordingly, an EMI shielding composite of polyvinyl alcohol/reduced-graphene oxide/iron hydroxide (PVA/rGO/alpha-FeOOH) films has been constructed in which a dielectric PVA, a conductive rGO and a magnetic alpha-FeOOH are playing a significant role in revoking the incident electromagnetic fields. The excellent distribution of FeOOH on the film surface facilitates the tuning of the electrical conductivity and impedance matching. Surprisingly, the films have showed a high electrical conductivity of 6.92 S/m at 4 wt.% rGO/FeOOH (>10(6) times than PVA) with an ultralow percolation threshold of 1.31 wt.% which is one of the smallest reported percolation thresholds in this regards. The PVA/rGO/FeOOH films have exhibited a large EMI shielding effectiveness (SET) of 28.27 dB with an SSE/t of 3624 dBcm(2)/g. The absorption is the main mode in the EMI shielding mechanism with (absorption coefficient A >= 0.5 and/or green shielding index gs >= 1) proving that the films can be classified under the umbrella of green shields. Besides, the thermal conductivity of films increased to be 2.23 +/- 0.07 Wm(-1)K(-1) at 4 wt.% rGO/FeOOH > 9-folds than that of PVA, raising the capability of the films to stand for long term stability of use by decreasing the probabilities of chemical degradations. The nano mechanical nature is tuned with the rGO/FeOOH, showing the highest Young modulus =3.03 +/- 0.15 GPa and the hardness= 1.7 +/- 0.03 GPa at 4 wt.%. The tensile mechanical properties are also improved, showing the highest tensile Young modulus =1.10 +/- 0.17 GPa and tensile strength =43.25 +/- 3.35 GPa at 4 wt.%. This work proposes a new (dielectric/electric/magnetic) scheme for the fabrication of flexible composite films with large EMI shielding ability, thermal conductivity and high tensile/nano mechanical nature which can be applied in diverse applications such as military, telecommunications, electromagnetic interference protection, healthcare, and electronics.