Lightweight polymer composites with synergistic electromagnetic interference shielding and thermal management for precision electronic devices

• A lightweight multifunctional foam composite for integrated EMI shielding, buffering, and thermal management. • Achieves 72.8 dB EMI SE with ultralow filler content (1.81 vol% total). • Tunable thermal conductivity (0.073–0.536 W/m·K) via conductive network design. • Excellent compression resilience and buffering from a unique foam-segregated structure. The increasing integration of precision electronics necessitates multifunctional materials capable of concurrent electromagnetic interference (EMI) shielding, mechanical buffering, and thermal management. Aiming to address this requirement, a multifunctional composite based on poly(vinylidene fluoride) (PVDF) and thermally expandable microspheres (TM) was fabricated. The surfaces of these PVDF and TM microspheres were subsequently precisely coated with Ti 3 C 2 T x (MXene) nanosheets and single-walled carbon nanotubes (SWCNTs) using a layered self-assembly technique via an electrostatic interaction regulation mechanism. The resulting material, PTMS (PVDF/TM/MXene/SWCNT), was subsequently used to fabricate a foam-segregated composite structure via thermal pressing. This material has an outstanding electrical conductivity of 8.77 × 10 −3 S·cm −1 and exceptional EMI shielding effectiveness of 72.8 dB (0.71 vol% SWCNT and 1.1 vol% MXene). Its unique foam-segregated structure confers lightweight properties (0.55 g∙cm −3 ) and excellent thermal conductivity (0.536 W/m·K). The addition of PVDF microspheres ensures that PTMS delivers remarkable buffering performance (compressive modulus of 71.3 MPa). The findings demonstrate the potential use of the composite as an integrated shielding, buffering, and thermal management solution for next-generation precision electronic applications.