Influence of the existence of a phthalocyanine phase on the dielectric properties of ternary composites: Carbon nanotubes/phthalocyanine/poly(vinylidene fluoride)

Carbon nanotube (CNT)/polymer composites with high dielectric constants are highly desired by the electronic and electric industries. However, high conductivity CNTs exhibit bad dispersion properties in polymers, leading to high dielectric losses in the composites. One effective strategy to overcome these problems involves the fabrication of core–shell structured fillers with CNT cores and non-conductive or semi-conductive shells. In this study, tetra-amido-phthalocyanine copper (4NH2-CuPc) coated, acidified multi-walled carbon nanotube (a-MWCNT) composites were fabricated through π–π stacking interactions. The coating thickness was controlled by adjusting the concentration of 4NH2-CuPc in the mixture and was subsequently confirmed by X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) analyses. The a-MWCNTs/4NH2-CuPc were added to poly(vinylidene fluoride) (PVDF) to produce a-MWCNTs/4NH2-CuPc/PVDF composites. The dielectric properties of these composites reached the optimum values when the rate of 4NH2-CuPc adsorption on the a-MWCNTs was the highest. A composite with 9 wt% a-MWCNTs and 13.5 wt% 4NH2-CuPc (mass ratio a-MWCNTs:4NH2-CuPc = 1:1.5) exhibited the largest dielectric constant (3200) and a dielectric loss tangent (2.1 at 1 kHz).