Improving the properties of poly(arylene ether nitrile) composites reinforced by covalently modified multi-walled carbon nanotubes

To develop high-performance carbon nanotube (CNT)-based polymer nanocomposites, both the interface control and the dispersion of CNTs within the polymer hosts need to be considered. In this study, we show an effective way to modify the surface of multi-walled CNTs (MWCNTs) by applying a cyclization reaction between nitrile-modified MWCNTs and bis-phthalonitrile. Fourier transform infrared spectroscopy, ultraviolet–visible spectroscopy, Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy were used to examine the structure and morphology of as-prepared functional CNTs. Phthalocyanines (Pcs) were found to be evenly coated on the surface of MWCNTs, resulting in good dispersion and strong interfacial adhesion between MWNCTs and the poly(arylene ether nitrile) (PEN) matrix. Compared with neat PEN, the tensile strength and tensile modulus of PEN nanocomposites with 2 wt% MWCNTs–Pc increased from 85.6 MPa to 108 MPa and from 2300 MPa to 3350 MPa, respectively. Furthermore, surface-functionalized CNTs can also form the physical MWCNT network within the PEN matrix, as confirmed by rheological and thermal stability tests. Additionally, a low rheological percolation threshold of 0.69 wt% was obtained, and the dielectric constant of PEN nanocomposites was increased from 3.3 for neat PEN to 16.6 with 5 wt% MWCNTs–Pc.