Graphene oxide liquid crystals: synthesis, phase transition, rheological property, and applications in optoelectronics and display

Abstract

Graphene oxide (GO) liquid crystals (LCs) are macroscopically ordered GO flakes dispersed in water or polar organic solvents. Since the first report in 2011, GO LCs have attracted considerable attention for their basic properties and potential device applications. In this review, we summarize recent developments and present a comprehensive understanding of GO LCs via many aspects ranging from the exfoliation of GO flakes from graphite, to phases and phase transitions under various conditions, the orientational responses of GO under external magnetic and electric fields, and finally Kerr effect and display applications. The emphasis is placed on the unique and basic properties of GO and their ordered assembly. We will also discuss challenges and issues that need to be overcome in order to gain a more fundamental understanding and exploit full device potentials of GO LCs.

Large Graphene Oxide Flakes: From Isotopic to Nematic Liquid Crystal Phase Transition

“…The minimum value that we observed for the pure nematic phase is lower than what is reported in the literature, even for GO LC made of size‐selected large flakes . The reason is directly related to the larger size of our GO flakes compared with what is typically studied . A low concentration of the pure nematic phase is very important for application of GO, for instance, in electro‐optical devices, for which the GO suspensions show excellent performance .…”

“…The reason is directly related to the larger size of our GO flakes compared with what is typically studied . A low concentration of the pure nematic phase is very important for application of GO, for instance, in electro‐optical devices, for which the GO suspensions show excellent performance . Our study of the stability of our GO suspension over 4 months, see Figure , clearly proves the stability of the low‐concentration nematic phase and the absence of any phase separation during this time and beyond.…”

“…The formation of such phases is dependent on the AR in which the thickness T is expected to be larger than the thickness of dried flakes, since in water the functional groups extend, and in addition, there is a hydration layer forming a larger effective thickness. However, the AR and shape of the building blocks are not the only effective factors, but there are also others such as the surface potential, responsible for the repulsive forces between flakes …”

Liquid Crystals of Carbon Compounds

“…% -в нема-тическую фазу. Такой широкий диапазон переход-ной концентрации, по мнению авторов [35], может быть объяснен большой полидисперсностью по ширине и толщине окиси гарафита.…”

2D Material Liquid Crystals for Optoelectronics and Photonics

“…43,75 The pH of the solvent also affects the critical concentration for the onset of liquid crystalline behaviour. 76 By tuning these separate parameters, it is possible to observe either a nematic phase or a columnar phase of the graphene oxide dispersion (Fig. 4).…”