Blue phase liquid crystals affected by graphene oxide modified with aminoazobenzol group

ABSTRACT

Liquid-crystalline blue phases (BPs) are stable only for very narrow temperature range between the isotropic and the chiral nematic phase that severely hinders their applicability. Herein, the aminoazobenzol group was chemically grafted onto epoxy group of graphene oxide (GO) via addition reaction. Successful grafting of aminoazobenzol group was confirmed using X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), UV–vis absorption spectra and thermogravimetric analysis (TGA). The resultant aminoazobenzol group–modified GO sheets, which is reduced (RGO-Az), were easily redispersable in common organic solvents or liquid crystals (LCs). By doping different contents of RGO-Az, nanosheets could stabilise BP and increase the BP range. When doped with 0.5 wt% RGO-Az, the mixtures show the wider range with 5.9°C than the range with 3.6°C of BPLCs without RGO-Az. Meanwhile, the phase sequence and the range of the aforementioned phases are reproducible upon heating and cooling, which shows that the BPs doped with RGO-Az nanosheets are thermodynamically stable.

GRAPHICAL ABSTRACT

KEYWORDS:

• Blue phase
• graphene oxide
• nanosheets
• stability

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the National Natural Science Foundation of China [grant number 51173017], [grant number 51373024], [grant number 51473020], [grant number 61370048]; National Key Basic Research Program of China [grant number 2014CB931804]; Fundamental Research Funds for the Central Universities [grant number FRF-TP-14-001A2]; Major Project of International Cooperation of the Ministry of Science and Technology [grant number 2013DFB50340]; and Beijing Higher Education Young Elite Teacher Project [grant number YETP0356].