From molecular assembly to multifunctional integration: Scalable fabrication of ultra-strong PPTA-based flexible films for smart protective systems

The synergistic integration of mechanical robustness with multifunctionality remains a critical challenge in flexible shielding materials. Here, a molecular engineering strategy using para -aramid (PPTA) prepolymers as reactive monomers in an NMP/CaCl 2 composite solvent system was introduced, through which high-molecular-weight PPTA (HMW-PPTA) solutions with an inherent viscosity of 4.1 dL·g −1 were synthesized via controlled secondary polymerization. Scalable blade-coating synergized with molecular assembly enabled rapid processing of these solutions into films exhibiting a tensile strength of 278.5 MPa, elongation at break of 14.3 %, and toughness of 23.5 MJ·m −3 . Hydrogen-bond-mediated in situ polymerization of conductive polypyrrole (PPy) on PPTA substrates yielded multifunctional PPTA-PPy (PAP) composite films. Dynamic interfacial interactions and nanoparticle-enabled defect repair synergistically enhanced the tensile strength and toughness of the optimized PAP (PAP-15) films to 311.4 MPa and 32.4 MJ·m −3 , respectively, alongside a high electrical conductivity of 1510 S·m −1 . Leveraging this conductivity, PAP-15 films achieve multifunctional integration, including 28.3 dB (8201 dB·cm 2 ·g −1 ) electromagnetic interference shielding effectiveness in the X-band, rapid Joule heating to 134 ℃ within 10 s at 5 V, and self-extinguishing behavior. This work establishes a universal platform for scalable production of high-performance PPTA-based flexible composites, overcoming traditional mechanical-functional trade-offs in shielding materials.