Highly stretchable, shape memory and antioxidant ionic conductive degradable elastomers for strain sensing with high sensitivity and stability

Abstract

Ionic conductive elastomers with high sensitivity, good mechanical property, shape memory and antioxidant capacity are of great significance in flexible smart wearable devices, but remains a challenge. Here we designed a series of degradable elastomers based on hexamethylene diisocyanate crosslinked poly(polycaprolactone citric acid)–co-dopamine (PCD) and 4, 4′-diaminodiphenyldisulfide with excellent mechanical property, shape memory property and antioxidation, and the ionic liquid is further introduced into elastomer leading to ionic conductive elastomer. The elastomer with 10 % 4, 4′-diaminodiphenyldisulfide shows tensile strain of 829 % and tensile stress of 5.48 MPa. After introducing 10 % ionic liquid, the ionic conductive elastomer’s conductivity increases to 1.18 × 10-6 S/cm while still maintaining 580 % break elongation. The elastomers can maintain good stability after cyclic stress–strain test and show high strain sensitivity to small deformation in joint motion signal monitoring. In addition, the elastomers have good shape memory property, cytocompatibility and in vivo biocompatibility. The mechanical response of elastomers was studied by employing the Mooney-Rivlin hyperelastic model. Further comparative analysis shows that the local stress concentration is the main factor leading to the failure of the elastomer. The ionic conductive elastomers with good conductivity, sensing sensitivity, mechanical strength and antioxidation are promising in the field of flexible wearable devices.

Keywords

• Ionic elastomers
• Shape memory
• Highly stretchability
• Antioxidation
• Strain sensors