Polyurea composites reinforced with polydopamine-modified cellulose nanofibers for high efficiency and adaptive sensors

This study introduces an innovative organic filler, polydopamine-coated cellulose nanofibers (PDA-CNF), designed to revolutionize self-healing materials by introducing abundant dynamic chemical bonds into polymer matrices. The synergistic interaction between dynamic hydrogen bonds and metal-ligand coordination enabled the creation of a series of composites exhibiting exceptional and highly tunable mechanical and self-healing properties. Notably, the Zn²⁺-enhanced composite exhibited a tensile strength of 5.8 MPa and a self-healing efficiency of 99.3%, demonstrating remarkable improvements of 444.6% and 101.7%, respectively, compared to the conventional composite without metal-ligand coordination. This innovation effectively breaks the long-standing trade-off between mechanical strength and self-healing efficiency in traditional polymers. By precisely adjusting the type and concentration of metal ions, the composites exhibit extensive tunability in stress (0.9–6.5 MPa), strain (3.7%–240.0%) and self-healing efficiency (70.4%–109.7%). This tunability enabled the development of multifunctional materials tailored for cutting-edge applications. Benefiting from such adaptive structural characteristics, the material delivers superior conductivity of 123 S·cm⁻¹ and a high EMI shielding efficiency of 56 dB, while exhibiting stable durability for advanced flexible wearable sensor devices. This work pioneers a novel platform for designing self-healing materials with advanced tunable functionalities, offering transformative potential for EMI shielding and sensor technologies.