Carbon Dot Initiated Synthesis of Poly(4,4'-diaminodiphenylmethane) and Its Methylene Blue Adsorption

Carbon dots (CDs) can generate free radicals in aqueous solutions which lead to their unique properties and many applications. The main goal of the current study is to employ CDs as initiators for the polymerization of the monomer 4,4'-diaminodiphenylmethane. Efforts have been recently focused on developing a polymerization process by using a facile one-step synthesis using HNO₃, CDs, and UV light as initiators. Here, this acidic polymerization process is similarly carried out by using just UV light and CDs with no other initiator. The newly synthesized poly(4,4'-diaminodiphenylmethane) (PDDM) was confirmed by several analytical techniques, including X-ray diffraction, scanning electron microscopy, Fourier-transform infrared spectroscopy, thermogravimetric analysis, and solid-state NMR spectra. The synthesis of PDDM was further probed for dye adsorption and it was found that the polymer well adsorbs methylene blue. Adsorption experiments were carried out by changing different parameters such as the initial concentration of methylene blue and the contact time for which the reaction progress was monitored by UV-visible spectroscopy.