Flexible High Strength and Thermally Conductive Nanocomposite Films for Effective Electromagnetic Interference Shielding After Harsh Conditions via Laser‐Induced Dissociation and Reconstruction

Abstract The 5G driven proliferation of electronics intensifies electromagnetic interference (EMI) and heat accumulation risks, spurring demand for polymer nanocomposites with high thermal conductivity and mechanical strength. conductive polymer poly (3,4‐ethylenedioxythiophene): polystyrene sulfonate (PEDOT:PSS) exhibit low strength, poor thermal dissipation, and limited electrical conductivity, failing to meet these requirements. Carbon nanotubes (CNTs) as promising fillers suffer from poor film forming ability, high defect density, and difficulty forming strong interfacial bonds with polymer matrices, thereby impairing the transport of both electrons and phonons. This study innovatively proposes a laser‐induced dissociation and reconstruction technique. By precisely modulating PEDOT:PSS/CNT interfacial interactions via laser processing, it achieves efficient molecular scale dissociation and reconstruction, overcoming bottlenecks of weak interfacial bonding and high defect density, while establishing continuous transport channels for both electrons and phonons. This significantly enhances the nanocomposite strength, thermal dissipation, and electrical conductivity. The composite exhibits breakthrough properties at ultralow CNTs content (4 wt%): ultrahigh electrical conductivity of 1.89 × 10 5 S m −1 , tensile strength of 143.7 MPa, thermal conductivity of 22.49 W m −1 K −1 , and exceptional EMI shielding effectiveness（SE）of 73 dB. Notably, its EMI SE performance remains stable under harsh conditions. Furthermore, the flexibility of laser endows the manufacturing of large‐area, customizable films.