Aqueous dispersion of multiwall carbon nanotubes with phosphonic acid derivatives
Abstract
The dispersing power of different phosphonic acid (PA) surfactants on multiwalled carbon nanotubes (MWCNTs) was examined: benzylphosphonic acid (BPA), hexylphosphonic acid (HPA) and decylphosphonic acid (DPA). UV-vis absorbance, transmission electron microscopy and zeta potential were employed to characterize the dispersion of MWCNTs in the aqueous phase. Among the three surfactants, DPA provided maximum dispersion stability while BPA and HPA provided minimum dispersion stability. We have shown that there exists an optimum weight ratio of surfactant to MWCNT of 1.5-1 for the effective dispersion of MWCNTs. The-potential values of the DPA-nanotube dispersion increased as the DPA concentration increased to reach a maximum value of-62 mV. The long hydrophobic chain of DPA was found to play a central role for the formation of stable MWCNT dispersions. The DPA-modified MWCNTs dispersions were used for the preparation of waterborne anticorrosive coatings. DPA-modified MWCNTalkyd coatings offers better corrosion protection to steel compared with the surfactant-free coating. The positive effect of DPA on the anticorrosion performance of MWCNT-alkyd coatings was related to its dispersing power on MWCNT and to its corrosion inhibitive properties. (C) 2016 Elsevier B.V. All rights reserved.