Surface properties of carbon black functionalized with pyrrole compounds

Carbon black (CB) is among the most important chemicals in the world and it is predominantly used as a pigment or reinforcing agent. The compatibility between CB and the matrix plays a key role in achieving the best performance of the composite material, mainly due to the surface properties of the CB. In this work, the surface characteristics of a furnace CB (N234) were modified by performing a solid state functionalization of CB with the following pyrrole compounds (PyCs): 2-(2,5-dimethyl-1H-pyrrol-1-yl)propane-1,3-diol (serinol pyrrole, SP), 2,5-dimethyl-1-octadecyl-1H-pyrrole (octadecylpyrrole, ODcP), 1-(triethoxysilyl)propyl)-2,5-dimethyl-1H-pyrrole ((3-amino)propyltriethoxypyrrole, APTESP), 2-(2,5-dimethyl-1H-pyrrol-1-yl)acetic acid (glycilpyrrole, GlyP), 1,2,5-trimethyl-1H-pyrrole (trimethylpyrrole, TMP). The synthesis of PyC and CB modification, with PyC content in the adducts ranging from about 6 % to 10 % by mass, were characterized by high atom efficiency and by very low E-Factor, resulting in a minimal amount of waste. The presence of PyC on the CB surface caused a reduction in the surface area and a change in the site energy distribution. The solubility parameters of CB/PyC adducts were found to be PyC dependent: stable dispersions of CB/PyC in water were obtained with the more hydrophilic SP and GlyP. This work presents a reliable and efficient method for controlling the surface properties of carbon black, potentially achieving matrix compatibility in different environments.