Photothermal-responsive self-healing PDMS-based elastomers for stretchable strain sensors

Abstract

The modification of traditional self-healing elastomers is typically accompanied by a loss of both strength and self-healing efficiency, limiting their long-term reliability. Developing multifunctional polydimethylsiloxane (PDMS)-based systems capable of overcoming this trade-off is thus critical for practical sensor applications. In this work, a photothermal-responsive self-healing PDMS elastomer (PUSE) was designed by constructing an elastomeric network from PDMS and isophorone diisocyanate (IPDI), with 4, 4′-dithiobisdiphenylamine (APDS) and epoxy-functionalized 2, 4, 6, 8 -tetramethyl – 2, 4, 6, 8 – tetra [3 – (hydroxyphenylmethoxy) propyl] cyclotetrasiloxane (TEC) as chain extenders. The synergistic effect of dynamic disulfide bonds and hydrogen bonds endowed the elastomer with reversible self-healing ability, while rigid phenyl and siloxane rings enhanced mechanical robustness. The optimized PUS₃E elastomer exhibited a tensile strength of 4.2 MPa, a toughness of 9.85 MJ m⁻³, and a resilience of 364.70%, Moreover, the self-healing efficiency reached 94.76% under UV irradiation within 24 h, surpassing 74.90% achieved at 70 °C, demonstrating the effectiveness of photo-thermal-assisted healing. The elastomer also showed hydrophobicity (water contact angle >100°) and optical transparency (T_550nm = 87.5%). PUS₃E was also utilized as the substrate for preparing resistive strain sensors that can accurately detect signals from the natural movements of the human body, making them highly valuable in the field of flexible sensors.