Investigation of the structure and thermal behaviour of polymer liquid crystal / single wall carbon nanotubes nanocomposite

INERA Workshop 2016: Membrane and Liquid Crystal Nanostructures

Exner, G.^1 ; Marinov, Y.^2 ; Perez, E.^3

Department of Experimental Physics, Faculty of Physics, Plovdiv University Paisii Hilendarski, 24 Tzar Asen str., Plovdiv, Bulgaria^1

Georgi Nadjakov Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee Blvd., Sofia

BG-1784, Bulgaria^2

Instituto de Ciencia y Tecnologia de Polimeros, Juan de la Cierva 3, Madrid

28006, Spain^3

关键词: Crystal phase transition;    Crystalline peaks;    Heterogeneous nucleation;    Lower temperatures;    Polymer liquid crystals;    Stabilization effects;    Structure formations;    Thermal behaviours;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/780/1/012011/pdf
DOI  :  10.1088/1742-6596/780/1/012011

来源: IOP

【 摘 要 】

In the present work, nanocomposite of thermotropic polymer liquid crystal poly(heptane-1,7-dyil biphenyl-4,4'-dicarboxilate) and single wall carbon nanotubes was investigated. Nanocomposite films were casted from solution blended polymer liquid crystal and nanotubes. The structure and thermal behaviour of the nanocomposite were investigated by means of X-ray scattering and differential scanning calorimetry. The results show that there are two phase transitions on cooling and a single one on subsequent heating for both the neat polymer liquid crystal and nanocomposite. Hence, the smectic order of the polymer liquid crystal as well as its monotropic behaviour are preserved in the nanocomposite. The isotropic melt - smectic transition temperature in the nanocomposite is several degrees higher and the enthalpy of this process is much lower, suggesting heterogeneous nucleation of this phase on the surface of the nanotubes. The temperature of crystal structure formation during further cooling decreases in the nanocomposite showing a stabilization effect of the nanotubes on the smectic phase. Judging from the smaller enthalpy of the smectic-crystal phase transition and the new crystalline peak in the X-ray scattering patterns of the nanocomposite one could suggest a new crystalline form formation and this crystalline phase coexistence with smectic phases at lower temperatures.