Covalent modification of reduced graphene oxide by chiral side-chain liquid crystalline oligomer via Diels–Alder reaction

Abstract

A effective way for covalent modification of reduced graphene oxide (RGO) by a chiral side-chain liquid crystalline oligomer (CSLCO) is firstly established. CSLCO consists chiral mesogenic units, non-mesogenic units with carboxyl groups and nematic mesogenic units with conjugated diene structure, the properties of materials should be determined by their structures. The conjugated diene structure can be grafted onto the RGO surface via Diels–Alder (DA) reaction, the chiral mesogenic units would enable CSLCO to have optical rotation and the carboxyl groups are expected to constitute coordination bonds with nano titanium oxide (TiO₂) to fabricate composites. Spectroscopic tools (Raman and XRD) are used to confirm the completion of the DA reaction. Fourier transform infrared imaging system is utilized to analyze the dispersibility of RGO in the RGO–CSLCO composites. Due to the excellent thermal property of RGO and the interactions between RGO and CSLCO, the dispersed RGO can increase the glass transition and the decomposition activation energy of CSLCO. RGO can enhance the photocatalytic degradation of TiO₂ due to its high electron mobility and large specific surface area. By preventing the aggregation of TiO₂ and RGO, the CSLCO covalently modified RGO is better than pure RGO to enhance the photocatalytic degradation efficiency of TiO₂.