Functionalization of carbon nanofibers with diamine and polyimide oligmer

This paper discusses the functionalization of oxidized carbon nanofibers (OCNF) with monomer and oligmer that mimic the structure of repeat unit of a polyimide (2,2-bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride-phenylene diamine). The goal was to covalently bind groups to the surface of OCNF that would both improve compatibility with the polyimide and potentially in case of the oligmer allow for chain entanglement in composite format. The reactions were carried out with or without initial activation by thionyl chloride (SOCl2). Functionalization following each reaction step was characterized using thermal gravimetric analysis (TGA), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). While quantitative analyzes indicated that the concentration of surface reactive oxygen groups was fairly low, the OCNFs were successfully functionalized with the aromatic diamine, dianhydride and the polyimide oligmer.