Highly stretchable supramolecular conductive self-healable gels for injectable adhesive and flexible sensor applications

Abstract

Synergistic supramolecular networks of conductive self-healable gels (CSGs) containing polythioctic acid (PTA), Fe³⁺ ion, pyromellitic acid (PA), and interpenetrating polyaniline (PANI) are synthesized and developed in this study. These non-covalent networks interlocked through physical (hydrogen, ionic, and coordination) bonds offer reversible supramolecular bonding and afford freely shapeable and injectable CSGs, which contribute to the high stretchability (more than 50-times elongation) as well as the ultrafast self-healable recoveries in mechanical and electrical timescales of 90 s and 0.7 s, respectively. The optimum supramolecular gel-based sensor shows an outstanding strain sensitivity (gauge factor = 11) along with a high tunable pressure sensitivity (2.8 kPa⁻¹). The stable electrical performance with high durability (>800 cycles) and excellent adhering properties to a wide range of substrates facilitate the detection of large (joint motion) and subtle (muscle movement) deformations of the human body. The real-life applications of multifunctional CSGs are further investigated through human motion detection, adhesive applications, and injectable writing as conductive inks for potential 3D printing.