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.