Development of conductive and biodegradable nanofibrous yarns : study of electrical and mechanical properties

Abstract

Electrically conductive and biodegradable materials are desired for a vast array of applications in wearable and flexible electronic areas to address the growing ecological problem of e-waste. Herein, we report on the design and fabrication of all-organic, conductive and biodegradable yarn using polyaniline (PANi) and polycaprolactone (PCL). The process of PANi incorporation is achieved in two ways; i) electrospinning a blend of PANi and PCL solution ii) in-situ polymerization of PANi on the nanofibrous surface of PCL electrospun fibers. The electrospun PANi incorporated webs are cut into ribbons and twisted to develop twisted yarns. A customized setup was used to produce continuous electrospun yarns. The effect of different degrees of PANi blended into PCL was investigated. Moreover, the effect of an array of aniline concentrations in coated fibers were studied. PCL/PANi blended solution with 2% PANi resulted in nanofibers with resistance of 10 ± 4 MΩ/cm. Fibers coated with 1% aniline concentration resulted in the core-shell fibers with of 50 ± 8 kΩ/cm. Increasing the number of plies of yarn to 3 plies resulted in a 3-fold reduction of the resistance. The twisted plied yarns were incorporated into fabric by stitching or weaving to demonstrate the stability of conductivity over mechanical forces. Both PANi blended and PANi coated yarns were found to be biodegradable in controlled environmental conditions. The use of PANi blended yarn as a biomaterial for tissue engineering and PANi coated yarns as a wearable electrode for capacitive sensors were demonstrated. The electromechanical behavior of PANi coated yarn is expected to provide inspiration for the production of highly sensitive strain sensors. This approach presents an early step on the way to the realization of all organic conductive biodegradable nanofibrous yarns for sustainable smart textiles.