Incubation Processes in Nematic 5CB + Multi-Walled Carbon Nanotubes Composites: Induced Optical Singularities and Inversion Walls, Percolation Phenomena
Vlad V. Ponevchinsky, Andrey I. Goncharuk, Sergey S. Minenko, Longin N. Lisetski, Nikolay I. Lebovka, and Marat S. Soskin
The incubation process of self-aggregated 5CB-MWCNT composites followed by nonlinear evolution of their optical, electroconductivity and thermodynamic characteristics were investigated and discussed for the first time. Induced optical singularities, the interfacial LC layers around the aggregates of nanotubes and inversion walls generated between them by the applied transverse electric field with voltage above the low threshold value Uth≥2.5V were measured and interpreted. The thermodynamic characteristics of 5CB+MWCNT composites were measured and their evolution during incubation was discussed. The obtained results give an insight for understanding the properties of 5CB+MWCNT composites. They are expected to help finding of the optimum conditions for synthesis of stable nematic LC+MWCNTs composites, which are important for practice. The incubation phenomenon is inherent to all composites with anisometric nanoparticles. Therefore, the obtained results and found regularities are of general importance.
Keywords: Multi-walled Carbon Nanotubes (MWCNTs); 5CB+MWCNTs composite; incubation of 5CB+MWCNTs composite to stable state; nanotubes self-aggregation to clusters with captured host molecules; induced speckled scattering and optical singularities; electrical percolation phenomena; differential scanning calorimetry (DSC); birefringent interfacial LC layer around aggregates; elastic forces created in 5CB by transverse electric field, inversion walls induced in the 5CB host by transverse electric field above Fredericksz threshold value