Surface Functionality Analysis By Boehm Titration Of Graphene Nanoplatelets Functionalized Via A Solvent-Free Cycloaddition Reaction

In this work, the functionalization of graphene nanoplatelets ( GNPs) performed by a solvent- free cycloaddition reaction on GNPs with iminodiacetic acid ( IDA) and paraformaldehyde ( PFA), and the functionality analysis of the resulting functionalized GNPs ( f- GNPs) by Boehm titration are introduced. The f- GNPs synthesized at different temperatures were characterized by X- ray diffraction ( XRD), Raman spectroscopy and scanning electron microscopy ( SEM) for structural and morphological properties. Back titration of the f- GNPs selectively identified 3 types of functional groups on the f- GNP surface, carboxylic, lactonic and phenolic, and suggested that 200 C gives the highest carboxylic group functionality. With the reaction temperature increasing from 180 to 220 C, a decrease in the phenolic functionality and an increase in that of lactonic are observed. In the case of 250 C reactions, it was found that the carboxylic functionality is greatly reduced, while the phenolic functionality showed a significant increase. The f- GNP samples were further characterized by thermogravimetric analysis ( TGA) and X- ray photoelectron spectroscopy ( XPS), the results of which showed a good agreement with the titration analysis.