Aggregation of clay platelets in nematic liquid crystal, 5CB: microstructure, electrical conductivity and rheological investigations

作者：Shaydyuk Y; Puchkovska G; Goncharuk A; Lebovka N^*

来源：Liquid Crystals, 2011, 38(2): 155-161.

DOI：10.1080/02678292.2010.533791

• liquid crystal
• 5CB
• organophilic nanoplatelets
• viscosity
• electrical conductivity
• microstructure

The microstructure, electrical conductivity and rheological properties of a nematic liquid crystal (5CB) doped at concentrations up to 4.5 wt% of montmorillonite (MMT) or organomontmorillonite (OMMT) clay nanoplatelets, were investigated at temperatures between 293 and 310K. Microscopy and electrical conductivity assessment revealed noticeable differences in aggregation in MMT and OMMT suspensions, MMT nanoplatelets showing a strong tendency to aggregation. The incubation of 5CB in the presence of MMT initially produced loose aggregation, followed by the formation of compact aggregates. The latter had practically no influence on the surrounding inter-aggregate regions. In the case of OMMT, a greater degree of integration of the nanoplatelets was observed within the liquid crystal structure of 5CB, resulting in a noticeable effect on electrical conductivity and activation energy of the composite material. Thixotropy was observed in suspensions of 5CB composites formed with either MMT or OMMT. A composite of 5CB with OMMT also exhibited anomalous viscous thinning at shear rates below 100 s-1. A structural model is suggested to explain this behaviour.

• 出版日期2011