Ionically conductive hydrogels constructed with the participation of aliphatic polycarbonates for multi-scenario flexible electronics and bioelectrical signal sensing

Abstract

Flexible conductive hydrogels have attracted much attention because of their high stretchability and signal response ability. In this work, a conductive hydrogel for multi-scenario applications was constructed. Polyvinyl alcohol (PVA) and polyethylene glycol–polycarbonate (PMCC) copolymers as well as carboxylated cellulose nanofibers (CCNF) were used to co-construct a flexible matrix, while aluminum bis(trifluoromethanesulfonyl)imide (Al(TFSI)₃) was introduced to endow the system with ionic conductivity and provide Al³⁺ coordination crosslinking. Multiple hydrogen-bonding interactions and Al³⁺ coordination synergistically formed a dual physically crosslinked network. DFT calculations confirmed at the molecular level that incorporating PMCC segments into PEG enhanced the multisite interaction capability of the resulting PEG-b-PMCC units. Benefiting from the above structural design, the hydrogel exhibits favorable tensile properties (maximum stress ≈ 300.4 kPa, fracture strain ≈ 308.4%) and toughness that meet the requirements of multiple application scenarios. Its conductivity increases significantly with the increase of Al(TFSI)₃ content, reaching 0.23 S m⁻¹ at 10 wt%. As a strain-sensing material, the hydrogel showed a piecewise sensitive response over the strain range of 0–300%, with a maximum gauge factor of 2.53. Based on these comprehensive properties, the hydrogel can be used in multi-scenario applications, including micro-expression recognition, speech monitoring, joint motion tracking and surface writing recognition, and can be used as a flexible bioelectrode to collect electrocardiogram and electromyogram signals. In addition, it can still stably output signals underwater for Morse code transmission and can be integrated into smart gloves to realize remote gesture control of robot detectors, demonstrating its application potential in the fields of wearable sensing and human–computer interaction.