Past Seminars Seminários Já Decorridos 2010

Phase transitions in confined binary mixtures of highly oriented rods

By: Daniel de las Heras
From: CFTC
At: Instituto de Investigação Interdisciplinar, Anfiteatro
[2010-11-18] 11:30

Liquid-crystals confined in narrow pores have been extensively studied because of their technological applications and the effect of confinement in the bulk phase behavior. In systems that exhibit a smectic phase, in which the molecules form layers, strong commensuration effects between the pore width and the smectic period appear, giving rise to new phenomenology. For instance layering transitions which involve changes in the number of layers inside the pore.

In contrast to the case of pure materials, confined mixtures of liquid-crystals have been given no attention. In this seminar, the behavior of a binary mixture of parallel hard cylindrical particles with dissimilar lengths (L1 and L2) confined by two parallel hard walls is analysed by means of a density functional approach. Confinement brings about profound changes in the bulk phase diagram, resulting from competition between the three relevant length scales: pore width, smectic period and length ratio L1/L2.