Rapid Construction of β ‐Cyclodextrin‐Functionalized Carbon Nanotubes Semi‐Interpenetrating Hydrogels for Flexible Sensors

ABSTRACT Conductive hydrogels hold great promise for applications in flexible sensors. However, for such soft hydrogel systems, achieving a synergistic integration of high mechanical robustness, excellent conductivity, and outstanding self‐healing capability remains a significant challenge. To address this issue, this study introduces β ‐cyclodextrin‐functionalized multi‐walled carbon nanotubes ( β ‐CD@MWCNTs) combined with a dynamic redox initiation system undergoing rapid polymerization to prepare hydroxyethyl cellulose/polyacrylic acid/ β ‐CD@MWCNTs (HEC/PAA/ β ‐CD@MWCNTs) semi‐interpenetrating network hydrogels. The incorporated β ‐CD@MWCNTs serve as additional physical crosslinking points within the system, which not only markedly enhance the mechanical properties of the hydrogel—including fracture strain (1407.28%), toughness (734.71 kJ m −3 )—while retaining the low modulus (13.08 kPa) characteristic of typical hydrogels, but also confer a remarkable self‐healing capability (with up to 88.65% healing efficiency for elongation at break). Furthermore, β ‐CD@MWCNTs can form a stable ion‐electron synergistic conductive pathway with Fe 3+ , endowing the hydrogel with excellent electrical conductivity (37.21 mS cm −1 ) and high strain sensitivity (gauge factor [GF] = 3.77). This study introduces functionalized carbon nanotubes, providing a novel strategy for developing high‐performance conductive hydrogels that combine low modulus with high stretchability, excellent conductivity, and self‐healing capability, underscoring their broad application potential in flexible sensing including human motion monitoring, information encryption, and handwriting anti‐counterfeiting.