Noncovalent modification of self-healing carbon nanotubes/polyurethane composites for high-efficiency electromagnetic wave absorption and multifunctionality

With electronic devices evolving towards higher operating frequencies and increased integration, traditional electromagnetic wave absorption (EMA) materials face the dual challenges of limited functionality and insufficient durability. This study introduces a new type of multifunctional EMA material based on ionic liquid-modified (ILs) CNT/polyurethane (ICPU) composites. These composites were prepared through a synergistic method that combines non-covalent modification with ILs and dynamic disulfide bonds. ILs facilitated the uniform dispersion of CNTs via π-π interactions, thereby creating multi-scale heterogeneous interfaces and inducing multiple modes of electromagnetic energy dissipation. Moreover, the disulfide bond network promoted the dynamic repair effect in the PU matrix. Results showed that ICPU composites achieved high EMA efficiency and rapid self-healing. The minimum reflection loss was -59.6 dB in the X-band at 1.9 mm and the crack healing efficiency was 93.7%. Additionally, the ICPU also achieved heat dissipation efficiency of 29.7% at 100℃ and high sensitivity with a gauge factor of 0.4275, due to the three-dimensional thermal conductivity network of CNTs and the elastic matrix. This research can enable the transition of modern multifunctional EMA materials from single absorption to adaptive multifunctionality.