Amino-ended hyperbranched polyamide-cross-linked conducting polymer hydrogels with enhanced performance for wearable electronics

Strain sensors are essential for accurately capturing intricate motions across various applications. However, achieving both high mechanical strength and stability in strain sensors remains challenging. Herein, we present a novel and high-performance strain sensor using an amino-ended hyperbranched polyamide (HBPN) as a cross-linker to construct a strong and tough conducting polymer hydrogel composed of polyvinyl alcohol (PVA) and poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS). The terminal amino groups in HBPN create non-covalent cross-links within the network, resulting in a robust structure. Notably, the unique hyperbranched topology of HBPN significantly enhances the hydrogel's properties, providing superior strength and toughness compared to its non-hyperbranched counterparts. Specifically, the distinctive macromolecular structure and abundant hydrogen bonding in the HBPN-PVA-PEDOT:PSS conducting polymer hydrogel result in exceptional toughness (991.53 kJ m^-3), which is five times higher than that of the PVA-PEDOT:PSS hydrogel without HBPN. Additionally, the HBPN cross-linker enhances the sensitivity of the conducting polymer hydrogel, making it more responsive than linear analogs when used as a strain sensor. The resulting sensors adapt dynamically to human motion, demonstrating excellent detection capabilities. This work showcases a promising approach for developing cost-effective, sustainable, flexible, and high-performance wearable devices.