Synthesis and Catalytic Application of Poly(2-acrylamido-2-methyl-1-propanesulfonic acid-co-acrylamide) Grafted on Graphene Oxide

Graphene oxide was grafted with poly(2-acrylamido-2-methyl-1-propanesulfonic acid-co-acrylamide) (GO-poly(AMPS-co-AM)) by free radical copolymerization of the corresponding monomers namely acrylamide (AM) and 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS). The benzoyl peroxide (BPO) was used as initiator. The GO-poly(AMPS-co-AM) was characterized by Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray diffraction (XRD), thermal gravimetric analysis (TGA), differential thermal analysis (DTA), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), UV-Vis and fluorescence spectroscopy, and elemental analysis. The GO-poly(AMPS-co-AM) exhibited the acidic site loading of 0.85mmol g(-1), the maximum degradation temperatures (T-max) of 212, 292, and 406 degrees C, the char yield of 30% at 800 degrees C, the limiting oxygen index (LOI) of 29.5, an estimated band gap of 4.7eV, and the fluorescence emission bands of 722, 800, and 880nm at the excitation wavelengths (lambda(max)) of 360, 400, and 440nm, respectively. The GO-poly(AMPS-co-AM) was used as a reusable catalyst for the preparation of 1,8-dioxo-octahydroxanthenes through the condensation of an aldehyde with 5,5-dimethyl-1,3-cyclohexanedione (dimedone) in H2O/EtOH (1:1) as green solvents at room temperature.