Bioinspired High-Strength and Super-Tough Polyurethane Nanocomposite Fibers: Synergistic Dynamic Hydrogen-Bonding and Noncovalent Functionalized MWCNTs

This study presents a bioinspired strategy to overcome the strength-toughness trade-off in polyurethane (PU) elastomers by engineering a synergistic dynamic hydrogen-bonding network. Herein, we developed a single-step, noncovalent functionalization of multiwalled carbon nanotubes (MWCNTs) using tannic acid (TA) and polyethylenimine (PEI), which enables uniform dispersion and strong interfacial interactions with PU. The resulting TA-PEI/MWCNTs/PU fibers exhibit unprecedented mechanical properties (true stress: 1.6 GPa, toughness: 690.2 MJ/m3), surpassing natural spider silk and conventional engineering materials. The innovation lies in the cooperative reinforcement mechanism: (1) TA-PEI/MWCNTs act as stress-transfer bridges via π–π interactions and hydrogen bonding; (2) dynamic H-bonds dissipate energy through reversible bond breaking; and (3) aligned microstructure enhances crack resistance. This scalable approach offers a paradigm for designing high-performance elastomers in flexible electronics and wearable devices.