• The WPU nanocomposite film with 30 wt% FG@CuP@ZTC shows a 55.6% improvement in limiting oxygen index (LOI), 66.0% and 40.5% reductions in peak heat release rate and total heat release, respectively, and a 93.3% increase in tensile strength compared to pure WPU film.
• The film achieves a high thermal conductivity of 12.7 W m−1 K−1 and a low dielectric constant of 2.92 at 106 Hz, addressing the need for efficient heat dissipation and low signal transmission loss in microelectronics.
• The trinity strategy of in situ self-assembly immobilization of CuP and ZTC onto fluorinated graphene (FG) creates a synergistic heterostructure that simultaneously enhances flame retardancy, thermal conductivity, and mechanical strength.
• This work provides a commercially viable, bionic layer-by-layer (LBL) design strategy for developing multifunctional polymer nanocomposite films suitable for high-power-density microelectronic thermal management.