Nanoscale Investigation of the Mechanical and Electrical Properties of Polyaniline/Graphene Oxide Composite thin Films Fabricated by Physical Mixture Method

Abstract

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Polyaniline (PANI), owing to its excellent electrochemical performance and ease of synthesis, has been a prominent material in applications concerning the optimization of supercapacitors. However, PANI suffers poor electrochemical stabilities and low cycle life, due to swelling and shrinking of the polymer backbone when subjected to continuous charge/discharge processes. Consequently, efforts have been made to address the agglomeration of PANI fibers, such as physically stretching the solution. Graphene oxide (GO), on the other hand, is a single layer of graphite with the presence of various oxygen-containing functional groups attached. Coupled with its excellent structural and mechanical properties that it inherits from graphene, the oxygen-containing functional groups in GO provide advantageous conditions that are favorable for its composite with polymers, such as PANI. Typically, PANI/GO nanocomposites are fabricated using electrochemical and in situ chemical oxidative polymerization methods, but a recent work has proposed a simple physical method to mix PANI and GO. Considering its high surface-to-volume ratio, GO can intercalate within the PANI fiber structure during physical mixture. Thus, the addition of GO might aid in reducing the agglomeration, while enhancing the electrical and mechanical properties of PANI. Our work focuses on probing the effect of GO on the nanoscale electrical and mechanical properties when composited with PANI, with the use of PeakForce Tunneling Atomic Force Microscopy (PF-TUNA). Our results may provide further understanding on the synergistic contributions of PANI and GO when composited with each other, for the applications in supercapacitor research.