A hybrid ionic liquid crystal comprising imidazolium surfactant-graphene oxide

ABSTRACTTo produce graphene oxide liquid crystal composites with better controllability, imidazolium surfactant with biphenyl mesogenic core (CBphCM) has been synthesised and used to modify the negatively charged surface of graphene oxide (GO) to obtain a hybrid ionic liquid crystal (CBphCM-GO). The process of GO and CBphCM recombination was monitored by various experimental techniques such as FT-IR, Uv-vis, Raman and XPS. The experimental results indicated that the C=O bonds on GO sheets are all reduced and C−O bonds are partially reduced due to the imidazolium units being electrically active and nitrogen-rich, and the presence of the N−O bonds indicates that a new hybrid is formed between CBphCM and GO. The recombination destroys the electrostatic repulsion balance among the GO lattices, and the CBphCM-GO is observed a fluffy appearance by TEM. The liquid crystal properties of CBphCM and CBphCM-GO were investigated by DSC, polarised optical microscopy (POM) and variable temperature X-ray diffraction, respectively. As an ionic liquid crystal, CBphCM has SmA as well as the rare SmC phases exhibits de Vries-like behaviour with a layer shrinkage. The liquid crystal properties of CBphCM-GO are derived from CBphCM, and the layer shrinkage behaviour from SmA to SmC phase has also been observed.KEYWORDS: Ionic liquid crystalimidazolium surfactantde Vries-like behaviorgraphene oxide AcknowledgmentsState Key Laboratory of Supramolecular Structure and Materials of Jilin University are thanked for their support for Dr Lixin Wu.Disclosure statementNo potential conflict of interest was reported by the author(s).Supplementary dataSupplemental data for this article can be accessed online at https://doi.org/10.1080/02678292.2023.2261874.Additional informationFundingThis work was mainly supported by the National Natural Science Foundation of China (NSFC) [22278172].