Grafting poly (methyl methacrylate) from azo-functionalized graphene nanolayers via reverse atom transfer radical polymerization

Graphene oxide (GO) was functionalized with (3-aminopropyl)triethoxysilane (APTES) from hydroxyl groups. Subsequently, 4,4'-azobis(4-cyanopentanoic acid) (ACPA) was attached to the APTES-functionalized GO to yield azo-anchored graphene (GOAzo). Then, grafting from reverse atom transfer radical polymerization of methyl methacrylate in the presence of GOAzo in different weight percents was carried out. The grafting ratio of APTES and ACPA was calculated to be 41 and 26 % via the data of N content from elemental analysis. Successful functionalization of GO with APTES, ACPA, and poly(methyl methacrylate) (PMMA) was also proved by XPS and FTIR. SEC results show that molecular weight and PDI values of the attached chains are higher. Expansion of graphene interlayer spacing and crystal structure of carbon in different graphenes were evaluated by XRD and Raman spectroscopy, respectively. Graft density of modifier and PMMA in various graphenes was evaluated by TGA. Finally, morphology of graphene nanolayers was studied by scanning and transmission electron microscopies.