Evaluation of mechanical and electrical parameters of individual polyaniline nanoparticles

I A Lobov, N A Davletkildeev, D V Sokolov, E Yu Mosur
2019 IOP Conference Series: Materials Science and Engineering  
The desire to reduce the size of electronic devices to the nanoscale makes new demands on the materials from which they are made. During the transition from the bulk structure to a separate nanoparticle, the properties of the material change significantly. Polyaniline (PANI) is one of the most important conductive polymers, which is widely used in various electronic applications. The most important characteristics of conductive polymers are mechanical and electrical parameters, the magnitudes
more » ... which largely depend on the production conditions. The properties of PANI have been investigated only with respect to its bulk state. Measurements, as a rule, are carried out on the polymer massive layers, therefore, the results are influenced by the contact interactions between PANI molecules. This paper presents the results of measurements of the electron work function, dielectric constant and elastic modulus of individual PANI nanoparticles containing a small number of molecules. The measurements were carried out in a single experiment using two methods of scanning force microscopy. PANI was obtained via chemical oxidative polymerization of aniline [1]. The PANI nanoparticles were separated from the bulk polymer by sonication in ethanol. A suspension of nanoparticles was deposited on a freshly split HOPG. Measurements of individual PANI nanoparticles using electrostatic force microscopy (EFM) and contact atomic force microscopy (AFM) were obtained using AFM MFP-3D (Asylum Research). The electron work function was determined from the magnitude of the positive phase shift in the EFM images using the technique described in [2] . We are using the negative phase shift measured from EFM images and the model described by [3] to measure the dielectric constant for nanoparticles of PANI. The magnitudes of the Young's modulus were determined by fitting the model curve constructed using the Hertz model for a conical probe to the force-indentation curves using the Asylum Research MFP-3D Hertz analysis tool. Figure 1. (a) AFM image, (b) EFM image of PANI nanoparticle, and (c,d) their cross-sections along line. Figures 1a,b show an example of AFM and EFM images of a PANI nanoparticle consisting of several polymer macromolecules, as well as their cross-sectional profiles showing the characteristic particle size of PANI (Fig. 1c ) and the contrast feature of its EFM image (Fig. 1d ). An increase in the EFM signal (oscillation phase of the cantilever) around the nanoparticle indicates the presence of conductivity in it. C D В А
doi:10.1088/1757-899x/699/1/012024 fatcat:ty7e5cckxzffvha37jwlvhgyue