Rheological studies on liquid-crystal colloids prepared by dispersing spherical microparticles with homeotropic surface anchoring

作者：Sahoo Rasmita; Dhara Surajit^*

来源：Liquid Crystals, 2017, 44(10): 1582-1591.

DOI：10.1080/02678292.2017.1309469

• Nematic colloids
• smectic-A colloids
• rheomicroscopy
• soft glass

We report rheological studies on the liquid-crystal colloids prepared by dispersing silica micro-particles with homeotropic surface anchoring in 8CB liquid crystal. In nematic colloids, a shear-thickening behaviour is observed in low shear rate region. The apparent yield stress of both the nematic and smectic-A (SmA) phases increases with increasing volume fraction of particles (phi). The critical strain amplitude (gamma(c), i.e., crossover of G' and G '') in SmA colloids decreases significantly with increasing phi. The frequency-dependent storage modulus of SmA colloids show a power-law behaviour (G'(omega) similar to omega(alpha)) and the loss modulus G ''(omega)) exhibits a shallow minimum. The optical rheomicroscopy shows that the nematic colloids form a network structure which are stretched and broken at high shear rate. When the temperature is decreased to SmA phase, the networks collapse showing regions of high-density particles. The variation of storage modulus with phi indicates that the SmA colloids response is dominated by defects.
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• 出版日期2017