Mechanical properties and interfacial compatibility of functionalized carbon nanotubes as fillers for chitosan solid polymer electrolytes

Abstract

Fillers added to enhance the mechanical properties of solid polymer electrolytes (SPEs) should have excellent mechanical strength and good interfacial compatibility. Carbon nanotubes (CNTs) can meet these requirements because these not only have excellent mechanical strength but can also be functionalized to form chemical bonds with the host matrices. However, the two requirements are contradictory to each other; as the walls of CNTs are replaced with more functional groups to increase the number of chemical bonds, their mechanical strength decreases and vice versa. Thus, to maximize the advantages of CNTs, these should be functionalized at an appropriate level. Nevertheless, most studies have focused only on the functionalization of CNTs, and an increase in their interfacial compatibility. Herein, multi-walled carbon nanotubes (MWNTs) substituted with different concentrations of acid chloride were prepared and used as fillers for chitosan SPEs. Their mechanical properties were investigated to determine the optimum functionalization level of MWNTs, and their ionic conductivities were measured as a function of the glycerol (plasticizer) and lithium salt (dopant) amounts for potential applications in practical SPEs.