Abstract
The highly conductive flexible graphene- nylon-6 composite film prepared in this study showed excellent response toward moisture sensing application for the first time. The mechanism of the excellent performance was explored and proposed using synergistic effects like (1) the interfacial linking between nylon-6 and graphene that played a major role in controlling electron movement, (2) the molecular-level interaction produced through the anchoring of water molecules by amide linkages, (3) the anchored moisture molecule creating an interfacial barrier for electron movement from one graphene surface to another through a graphene nylon-6 bridge, and (4) graphene itself absorbing the moisture molecules, which collectively produced a significant resistance to obtain the sensing signals for water molecules. The demonstrated interface chemistry through the molecular-level interaction of moisture and nylon-6 polymer molecules was found to be highly useful in realizing a higher sensing performance. The sensing was 100 times faster than that observed with the current conventional sensors. The calculated Young modulus and electrical conductivity of the composite film showed excellent mechanical and electrical properties. Additionally, the reversibility data of the sensor showed outstanding performances. Therefore, excellent sensing performance based on a very short response time, quick reversibility, retained sensitivity, and flexibility made it a viable candidate for moisture sensing application.