Triphasic ATH@rGO-CoFe₂O₄ hybrid nanofiller-integrated waterborne polyurethane composites for dual functionality: fire retardancy and EMI shielding

This study introduces a novel bifunctional composite of waterborne polyurethane (wPU) integrating with the ATH@rGO-CoFe₂O₄ core@shell hybrid nanofiller, which is synthesized by encapsulating aluminum trihydrate (ATH) with reduced graphene oxide (rGO) and subsequently depositing CoFe₂O₄ nanoparticles. The uniform dispersion of the hybrid nanofiller within the wPU matrix as facilitated by APTES functionalization results in significant enhancement in mechanical, thermal, fire-retardant, and electromagnetic interference (EMI) shielding properties. Mechanical tests indicate optimal tensile strength and Young's modulus at a filler loading of 10 wt%, along with an equilibrium between strength and elongation. Thermal analyses reveal enhanced thermal stability due to the synergistic effects of the high thermal conductivity derived from rGO and water-release behavior caused by ATH, thereby leading to an increased LOI% of 26.8 and a V-2 rating of UL-94 testing. EMI shielding efficacy demonstrated good performance, driven by the conductive rGO network and impedance-matching capabilities of CoFe₂O₄, achieving a maximum shielding efficiency of 21.42 dB at a filler loading of 30 wt%. This study corroborates the potential of the ATH@rGO-CoFe₂O₄ hybrid nanofiller in developing high-performance polymer composites that provide distinctive advances of mechanical strength, thermal stability, fire retardancy, and EMI shielding for cutting-edge applications, such as flexible electronics, protective coatings, and sustainable materials.