Evaluation in concentration of surface amino groups upon doped and dedoped Fe3O4/PANI nanocomposites through conjugation with p-hydroxybenzaldehyde

Abstract

An in situ chemical oxidation polymerization approach in combination with dedoping treatment was employed for preparing Fe3O4/polyaniline (Fe3O4/PANI) and dedoped Fe3O4/PANI nanocomposites. The two magnetic nanocomposites were featured with relatively high-saturation magnetization, superparamagnetism, and a multicore–shell structure. Both S and Cl species can be doped into PANI shell. The doping level of Fe3O4/PANI nanocomposite was estimated to be 30.9% through X-ray photoelectron spectroscopy. After dedoping treatment, about 95% S and 40% Cl can be removed from PANI shell. More significantly, a spectroscopic method has been developed for estimating the concentration of amino groups on surface of PANI-coated nanocomposites through nucleophilic addition between amino and p-hydroxybenzaldehyde. The concentration of surface amino groups was estimated to be ca. 357.1 and 554.5 μmol g−1, corresponding to the doped and dedoped magnetic nanocomposites, respectively.