Collectively Reinforced Brick-and-Mortar Nanocomposite Films with High EMI Shielding Performance and Superior Folding Reliability

A highly flexible and lightweight electromagnetic interference shielding (EMIS) nanocomposite film with enhanced mechanical properties and outstanding folding reliability was developed through the construction of a collectively reinforced brick-and-mortar architecture based on controlled intercomponent interactions. A molecularly designed conjugated polyelectrolyte surfactant was synthesized to noncovalently disperse nanocarbon fillers, and its dispersing behavior was rationalized using density functional theory calculations. Graphene nanoplates (GNPs), cellulose nanofibers, and a heterocyclic matrix were integrated as conductive bricks, reinforcing nanoglues, and a flexible cohesive mortar, respectively. Carbon nanotubes were further introduced as conductive nanobridges to improve interplatelet electrical connectivity and nanoscale mechanical reinforcement. The coordinated assembly of these designed and selected components generated multiple intercomponent interactions, including π-π, ionic, and hydrogen bonding, thereby producing a cohesive brick-and-mortar nanoarchitecture with strongly integrated GNP-based conductive layers. Consequently, the optimized nanocomposite thin film, with a thickness of 100 μm, achieved an EMIS effectiveness of 44.12 dB in the X-band range. Compared with previously reported foldable EMIS films with thicknesses ranging from 6 to 3,000 µm, the resulting film exhibited superior folding reliability, enduring 200,000 folding/unfolding cycles while largely retaining its electrical conductivity and EMIS performance. These results are attributed to the collective reinforcement of the brick-and-mortar nanoarchitecture, formed through controlled intercomponent interactions. The proposed mechanism further explains how this nanoarchitecture is formed and how it contributes to the enhanced properties, EMIS performance, and folding reliability.