Kinetics of nanocolloids in the aligned domain of octylcyanobiphenyl and aerosil dispersion

Abstract

In this study we explore the interesting kinetics of nanocolloids formed by the solvent dispersion method (SDM) in an aligned matrix of octylcyanobiphenyl (8CB) liquid crystals and aerosil nanoparticles. The presence of alignment changes the behaviour of the induced crystallisation (IC), and melting transition (K–SmA) observed in the aligned nanocolloidal liquid crystal samples when compared with unaligned samples. Heating‐rate‐dependent experiments were performed for the aligned and unaligned samples at various heating ramp rates varied from 20 to 1 K min⁻¹ using a calorimetric technique. In the aligned samples, the IC transition peak shifts towards higher temperature, whereas the melting transition peak shifts towards lower temperature. The IC peak shows an increase in enthalpy whereas the melting transition shows a decrease following an Arrhenius behaviour. The presence of alignment increases the activated kinetics of the system. This behaviour can be explained in terms of molecular interaction between aligned domains of nanocolloids in the 8CB matrix which makes the material stiffer.

Keywords:

• liquid crystal
• Arrhenius theory
• surface kinetics
• calorimeter
• magnetic effect on phase transitions

Acknowledgements

The author is grateful to Germano Iannacchione for many useful discussions and to J. C. MacDonald for help with the DSC instrument.