Conductive epoxidized natural rubber/Chitin nanocrystals/Polyaniline composite with high toughness, high strength, and low-hysteresis as flexible strain sensors

Low hysteresis and mechanical toughness are important to improve the accuracy and timeframe of use of flexible sensors.However, constructing conductive flexible sensors with high mechanical strength, low hysteresis, and high toughness simultaneously remains a challenge. In this work, we construct an entangled crosslinked topological network with physical interactions to fabricate conductive flexible sensors with high mechanical properties, toughness, and hysteresis. Predeacetylated Chitin nanocrystals (ChNCs) were grafted onto epoxidized natural rubber (ENR), and then PANI was polymerized in situ. ChNCs with amino groups serve as templates for ANI polymerisation and provide junctions in the crosslinked network, enhancing molecular chain entanglement and crosslinking. Upon loading, molecular chain conformations spontaneously adjust to equilibrium. Meanwhile, hydrogen bonds and electrostatic interactions with low strength exist between the polymer matrix and conductive fibres, which could rapidly break and reform during cyclic deformation. Therefore, the synergistic interaction of topology network and physical interaction endows materials with high mechanical properties (2.5 MPa, 1000%) and low energy dissipation ratio (13.6% in 300% cyclic strain) and hysteresis (13.3% in 300% cyclic strain). This work shows an effective method to prepare conductive flexible sensors with high toughness, high strength and low hysteresis for human body signals detection. The sensor shows a good electrical response to external stress, which can be used to monitor the movement of human joints. This work develops an effective strategy for manufacturing tough conductive sensors exhibiting low hysteresis, high toughness, and strength, indicating potential for healthcare technologies.