Influences of hybrid carbon nanofillers on structures and electrical properties of sulfonated poly(1,3,4‐oxadiazole)‐based composite films

Sulfonated poly(1,3,4‐oxadiazole) (sPOD)‐based composite films, including 10 wt % hybrid carbon nanofillers composed of different weight ratios of multiwalled carbon nanotube (MWCNT) and graphene sheets, were manufactured via an efficient ultrasonication‐assisted solution mixing and casting. Fourier transform infrared (FTIR) spectra of the composite films confirmed the existence of specific interactions between sPOD backbone and MWCNT or graphene sheet. Transmission electron microscopic (TEM) images of cross sections of the composite films showed that 2‐dimensional (2D) graphene sheets formed an anisotropically oriented structure in the sPOD matrix film, but they are randomly dispersed owing to the introduction of 1‐dimensional (1D) MWCNT. Accordingly, the electrical resistivity of the composite films decreased largely from ～10³ Ω cm to ～10¹ Ω cm with the increment of the relative MWCNT content in hybrid carbon nanofillers due to the synergistic bridging effect. Thus, sPOD‐based composite films with 10 wt % hybrid carbon nanofillers exhibited high performance in electric heating by attaining rapid temperature responsiveness, high electric power efficiency, and stable maximum temperatures under given applied voltages. It was also revealed that the hybrid composite films were operationally stable over a long‐term stepwise electric heating experiment. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44499.