Remote and efficient infrared induced self-healable stretchable substrate for wearable electronics

Abstract

Flexible and wearable electronics as candidates for the next-generation electric devices have attracted wide attention and been actively investigated recently. A remote, fast and efficient self-healable stretchable polyurethane nanocomposite for the substrate of flexible wearable electronics is reported in this paper. Carbon nanotubes (CNTs) were embedded in a self-healing polyurethane based on disulfide bonds. The tensile strength at break of the composites was improved significantly from 1.01 MPa to 3.64 MPa when the content of CNTs was 5 wt%. The elongation at break decreased as the addition of CNTs, but still remained at the high level above 300%, indicating the composites had enough flexibility for stretchable wearable electronics. The damages of the composites could be healed by near-infrared (NIR) irradiation remotely and quickly due to the photothermal effect of CNTs. The healing efficiencies were over 80% after 1 min of NIR irradiation. The nanocomposites exhibited volume resistivity values in the range of 1.31 × 105 to 1.65 × 105 Ω cm as a result of the incorporation of CNTs which could meet the requirements for electrostatic charge dissipation (ESD) materials requiring conductivities in the range of 105 to 109 Ω cm. The conductivity of the broken electric circuit fabricated by silver paste drop-cast on the composite strip was completely recovered after 1 min of NIR irradiation. These results demonstrate that the nanocomposites in this work can be used as substrates of electrical devices, especially for flexible wearable electronics. The electrical devices can be healed by remote NIR irradiation quickly and precisely.