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

Excellent dispersion of nanofillers like carbon nanotubes (C-NTS) 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 (C-DOTS) have been used as dispersion aid to debundle C-NTS in carboxylated acrylonitrile butadiene rubber (X-NBR) latex. The amine groups of C-DOTS have been covalently conjugated with the acid groups of C-NTS and X-NBR latex through amide bond formation that leads to enhanced interactions between X-NBR and C-NTS through C-DOTS. In addition, C-DOTS weaken the strong intertubular van der Waals attraction between the C-NTS which results in the efficient dispersion of high aspect ratio C-NTS in the X-NBR 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 C-DOTS with C-NTS and X-NBR latex. The mechanical, dynamic mechanical, thermal stability and thermal conductivity properties of the X-NBR-C-DOTS-C-NTS hybrid nanocomposites are prominently higher when compared to neat X-NBR, X-NBR-C-NTS nanocomposites and X-NBR-C-DOTS nanocomposites. From transmission electron microscopy (TEM) and atomic force microscopy (AFM) studies it has been ascertained that the C-DOTS act as an interconnector between C-NTS that prevents agglomeration of C-NTS in the X-NBR matrix.