Synthesis and characterization of liquid crystalline polyester/graphene and a study of their properties

A new rod-like thermotropic liquid crystalline polyester (TLCP) material and its nanocomposites based on different concentrations of graphene were synthesized by in-situ high-temperature solution polymerization. The resulting nanocomposites were characterized using XRD, microscopic analysis (POM, SEM, and TEM), spectroscopic analysis (FT-IR, UV-Vis, and fluorescence), and thermal analysis (TGA and DSC). The XRD and POM methods showed that the composite materials exhibited only the nematic phase. The TEM images revealed that the graphene were distributed in the polymer with sizes ranging from 100 to 200 nm. The absorption spectroscopy data showed that the electronic properties of graphene were mostly retained without damaging their two-dimensional electronic properties, together with the analysis of the maximum absorption spectrum and concentration of the composites in terms of the Lambert-Beer law. The fluorescence from the TLCP moiety was almost completely quenched and red shifted by graphene, indicating that the linkage mode facilitated effective energy and electron transfer between the rod-like TLCP and the extended pi-system of graphene. Therefore, this novel nanocomposite material exhibits excellent thermal properties based on the thermogravimetric analysis.