Enhancing multiwalled carbon nanotubes/ poly(amide-imide) interfacial strength through grafting polar conjugated polymer on multiwalled carbon nanotubes

Abstract

In this study, a polar conjugated polymer (poly(o-methoxyaniline), POMA) was for the first time grafted onto multiwalled carbon nanotubes (MWCNTs) as we know, and the MWCNTs grafted POMA (POMA-g-MWCNTs) as filler was incorporated into poly(amide–imide) (PAI) to fabricate PAI/POMA-g-MWCNTs conductive polymer composites (CPCs). In PAI/POMA-g-MWCNTs CPCs, MWCNTs constructed conductive phase, PAI constructed polymer matrix phase, and the grafted POMA on the surface of MWCNTs blended with PAI matrix constructed POMA/PAI mixed phase. The mixed phase enhanced the interfacial strength between conductive filler and polymer matrix through the strengthened hydrogen bond interaction, and improved the dispersion of conductive filler in the polymer matrix compared to the PAI/MWCNTs binary and PAI/POMA/MWCNTs ternary blend, which is helpful for charge, load, and thermal transfer. As a result, the electrical conductivity increased from 13.5 S m–1 for PAI/MWCNTs binary blend to 48.4 S m–1 for PAI/POMA/MWCNTs ternary blend, and further increased to 79.6 S m–1 for PAI/POMA-g-MWCNTs grafted blend. In addition, the tensile strength increased from 50 MPa for PAI/MWCNTs binary blend to 65 MPa for PAI/POMA/MWCNTs ternary blend, and further increased to 74 MPa for PAI/POMA-g-MWCNTs grafted blend. These results suggested that grafted polar conjugated polymer onto the surface of carbon nanotubes is an effective way to improve the miscibility between carbon nanotubes and polymer matrix.