Unique approach to debundle carbon nanotubes in polymer matrix using carbon dots for enhanced properties

Abstract

Excellent dispersion of nanofillers like carbon nanotubes (CNTS) in an aqueous medium of rubber latex through covalent interactions is required to achieve extraordinary reinforcement at very low filler concentration. Herein, aqueous dispersible carbon dots (CDOTS) have been used as dispersion aid to debundle CNTS in carboxylated acrylonitrile butadiene rubber (XNBR) latex. The amine groups of CDOTS have been covalently conjugated with the acid groups of CNTS and XNBR latex through amide bond formation that leads to enhanced interactions between XNBR and CNTS through CDOTS. In addition, CDOTS weaken the strong intertubular van der Waals attraction between the CNTS which results in the efficient dispersion of high aspect ratio CNTS in the XNBR matrix and thereby significantly improves the overall properties. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) studies establish the success of covalent conjugation of CDOTS with CNTS and XNBR latex. The mechanical, dynamic mechanical, thermal stability and thermal conductivity properties of the XNBR-CDOTS-CNTS hybrid nanocomposites are prominently higher when compared to neat XNBR, XNBR-CNTS nanocomposites and XNBR-CDOTS nanocomposites. From transmission electron microscopy (TEM) and atomic force microscopy (AFM) studies it has been ascertained that the CDOTS act as an interconnector between CNTS that prevents agglomeration of CNTS in the XNBR matrix.