Zwitterionic Surfactant Modified Carbon Nanotubes Incorporated Percolative Polymer Composites with Improved Features

Abstract

Modification of carbon nanotubes (CNTs) and their incoporation in polymer matrix have attracted much attention of researchers. As maximum dispersion of CNTs could enhance the properties of matrix dynamically, researchers are trying to find new methodologies to obtain this target. However, maximum dispersion remains a great challenge and under the stage of progress. Here, we claimed the synthesis of composites with a highly uniform dispersion of the filler that results significantly improved electrical features. In this regard, composites of polymethylmethacrylate (PMMA) were fabricated by using pristine and zwitterionic surfactant (ZIS) modified CNTs (ZIS-CNTs). Characterization was done by using ultraviolet–visible (UV–Vis), Fourier transform infrared (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermo gravimetric analysis (TGA) techniques. UV–Vis and FTIR spectroscopy confirmed the synthesis of ZIS-CNTs and composites. UV–Vis spectra showed an increase in wavelength with the decrease in optical band gap for CNTs-based (CNTs/PMMA) and ZIS-CNTs-based (ZIS-CNTs/PMMA) composites. SEM and XRD studies confirmed a significant homogenoeus and uniform dispersion of CNTs in ZIS-CNTs/PMMA composites. An increase in conductivity of PMMA from 10−9 to 10−2 and 10−1 S/cm was observed on addition of less than 1% (mass fraction) of CNTs without and with modification by ZIS, respectively. Low values of percolation threshold at 0.5% and 0.005% for CNTs/PMMA and ZIS-CNTs/PMMA composites were obtained, respectively. TGA analysis showed a slow rate of decomposition for composites than that for pure PMMA. Around 600 °C, 3% CNTs/PMMA and 7% ZIS-CNTs/PMMA composites were left in the end, which depicts the increase in thermal stability of PMMA. This work depicts a better dispersion of CNTs in PMMA matrix via slight modification in synthesis as well as by using ZIS as surfactant.

Keywords

• polymer composite
• enhanced dispersion of carbon nanotubes (cnts)
• increased electrical conductivity
• low percolation threshold
• improved thermal stability