Electroconductive nylon-6/multi-walled carbon nanotube nanocomposite for sodium sensing applications

Abstract

Abstract Developing smart fabric materials that can withstand stress, strain, and bending is a key factor to successful integration into smart clothing. The aims of this study were 1) development and characterization of multiwall carbon nanotube (MWCNT)- based electroconductive materials for sensing applications, 2) optimization of experimental fabrication parameters to sensor response, 3) optimization of experimental fabrication parameters for mechanical properties. Nylon-6/MWCNT nanocomposites have enhanced mechanical and electrical properties which make them an ideal candidate for integration into smart clothing. Nylon-6/MWCNT nanocomposites were fabricated by functionalizing an electrospun Nylon-6 scaffold for selective sodium detection. Selective sodium detection is realized using a calixarene functionalization of the MWCNT and the MWCNT is only responsible for increased charge transfer of the nanocomposite. Initially, three factors were considered for optimization of nylon-6/MWCNT nanocomposite fabrication: nanotube type, nanotube concentration, and the weight percent of nylon in the electrospinning solution. The sensing nanocomposite materials were characterized for the electrical and mechanical properties. The sensitivity of the sensor to changing sodium ion concentration (µA/mM) was optimized for 20wt% nylon-6 nanofiber base functionalized in a solution of 0.5 mg/mL of CNT. The optimized sensor has a nanotube length less than 0.2 microns and fiber diameter ranging between 0.25-0.32 microns. The target-controlled coat weight is 20 GSM (g/m2) for electrospun nylon nanofibers. Secondly, the impact of electrospinning conditions, particularly flow rate, on sensor response was considered. Sensor materials produced at an electrospinning flow rate of 1.0 mL/min had an enhanced stress at break, compared to neat nylon-6, without sacrificing elasticity. Additionally, sensors produced at electrospinning flow rates of 1.0 mL/hr maintain their sensor response for approximately 20 stretches with no statistical difference between sensor response of the stretched and unstretched sensors.