Noncovalent functionalization of graphene with pyrene-terminated liquid crystalline polymer

Abstract

Pyrene-terminated liquid crystalline polymers (poly [8-(4-cyano-4′-biphenyl)-1-octanoylacrylate] and poly [6-(4-cyano-4′-biphenyl)-1-hexanoylacrylate]) were synthesized and used to functionalize graphene sheets via π–π interactions. The resulting liquid crystalline polymers functionalized graphene sheets were characterized by UV–vis spectroscopy, fluorescence spectroscopy, thermal gravimetric analysis, Fourier transform infrared spectroscopy, X-ray diffraction, atomic force microscopy and Raman spectroscopy. It was found that an intercalated layer structure was formed when polymer was grafted onto graphene sheets. The liquid crystalline polymers were able to effectively disperse graphene in N,N-dimethylformamide that were stable for months. Additionally, a remarkable smaller distance of adjacent mesogenic units was observed, which is attributed to the confinement of the polymer chains between 2D reduced graphene oxide sheets.