The effect of CoPt-coated reduced-graphene oxide nanosheets upon the Smectic-A to Smectic-C* phase transition of a chiral liquid crystal

ABSTRACT

We report on high-resolution calorimetry and small-angle X-ray scattering measurements along the Smectic-A to chiral Smectic-C* phase transition of the liquid crystal 4-(2-methyl butyl) phenyl 4-n-octylbiphenyl-4-carboxylate with dispersed, CoPt nanoparticle-coated reduced-graphene oxide nanosheets. The temperature dependence of heat capacity and smectic layer spacing are obtained in the vicinity of Smectic-A to chiral Smectic-C* phase transition. Though no remarkable pretransitional effects are present, the critical fits show a crossover from mean-field near a tricritical point to classical mean-field compared to pure liquid crystal. The X-ray data yield a dilation of smectic layer thickness, indicating the assembly of graphene oxide nanosheets between the smectic layers.

GRAPHICAL ABSTRACT

KEYWORDS:

• Reduced graphene oxide
• nanoparticles
• nanosheets
• X-ray scattering
• ac calorimetry
• smectic liquid crystals
• extended mean-field

Acknowledgments

M.L. acknowledges the support of Project P1-0125 of the Slovenian Research Agency. G.C. acknowledges the support of Project CZ.02.2.69/0.0/0.0/16_027/0008465 for Mobility of Researchers under the Operational Programme Research, Development and Education and of Project PE3-1535 implemented within the framework of the Action “Supporting Postdoctoral Researchers.” G.N. and I.L. acknowledge the support of THALES Project of the Operational Strategic Plan “Education and Lifelong Learning”, co-financed by the European Social Fund and the State of Greece.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the European Social Fund [PE3-1535,THALES Project]; Slovenian Research Agency [P1-0125]; European Regional Development Fund and European Social Fund - Project “International Mobility of Researchers in CTU” [CZ.02.2.69/0.0/0.0/16_027/0008465].