Poly(9,9'-diheylfluorene carbazole) functionalized with reduced graphene oxide: convenient synthesis using nitrogen-based nucleophiles and potential applications in optical limiting

Covalently functionalized reduced graphene oxide (RGO) sheet was prepared by treating nitrogen-centered anions generated from poly(9,9'-diheylfluorene carbazole) (PCF) with GO. The resultant hybrids with different chemical behavior were separated by centrifugation. The covalent modification was fully characterized by IR spectroscopy, UV/Vis spectroscopy, thermogravimetric analysis (TGA), Raman spectroscopy, TEM, and SEM. It was found that RGO-PCF-s, the soluble part, was split into small platelets with a size of about 200 nm, and the hydrophobic polymer PCF became hydrophilic after wrapping by RGO. The content of RGO in RGO-PCF-s was about 11.9%, and the hybrid material showed good dispersion stability in water. Besides, RGO-PCF-i, the insoluble part, with larger size, displayed excellent optical-limiting response, in which both nonlinear absorption and nonlinear scattering play important roles. As nitrogen-centered anions are an important type of intermediates in chemistry, this one-step "grafting-to" strategy could be used to obtain RGO-based materials with different applications.