Functionalization of reduced graphene oxide nanosheets via stacking interactions with the fluorescent and water-soluble perylene bisimide-containing polymers

Reduced graphene oxide (RGO)-polymer composites were prepared via π–π stacking interactions of RGO with the perylene bisimide-containing poly(glyceryl acrylate) (PBIPGA). PBIPGA was synthesized via atom transfer radical polymerization (ATRP) of solketal acrylate (SA), using bifunctional N,N′-bis{2-[2-[(2-bromo-2-methylpropanoyl)oxy]ethoxy]ethyl}perylene-3,4,9,10-tetracarboxylic acid bisimide (PBI-Br) as the initiator, and subsequent hydrolysis of the acetal-protecting group. PBIPGA was characterized by 1H NMR spectroscopy, gel permeation chromatography (GPC), UV–visible absorption spectroscopy and fluorescence spectroscopy. The presence of π–π stacking interactions between PBI and the RGO surface was suggested by fluorescence and UV–visible absorption spectroscopy results. The chemical states and π–π stacking interaction, morphology, and composition of RGO-PBIPGA composites were characterized, respectively, by X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). The low cytotoxicity level of the RGO-PBIPGA composites was revealed by incubation with 3T3 fibroblasts in 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assays in vitro.