Interplay between columnar and smectic stability in suspensions of polydisperse colloidal platelets

Abstract

The phase behavior of a model suspension of colloidal polydisperse platelets is studied using density-functional theory. Platelets are modelled as parallel rectangular prisms of square section $l$ and height $h$, with length and height distributions given by different polydispersities ${\delta }_l$ and ${\delta }_h$. We obtain the phase behavior of the model, including nematic, smectic and columnar phases and its dependence with the two polydispersities ${\delta }_l$ and ${\delta }_h$. When ${\delta }_l>{\delta }_h$ we observe that the smectic phase stabilises first with respect to the columnar. If ${\delta }_h>{\delta }_l$ we observe the opposite behavior. Other more complicated cases occur, e.g. the smectic stabilises from the nematic first but then exists a first-order transition to the columnar phase. Our model assumes plate-rod symmetry, but the regions of stability of smectic and columnar phases are non-symmetric in the ${\delta }_l-{\delta }_h$ plane due to the different dimensionality of ordering in the two phases. Microsegregation effects, i.e. different spatial distribution for different sizes within the periodic cell, take place in both phases.

22 pages, 5 figures

References in corpus (6)

• Polydispersity stabilizes Biaxial Nematic Liquid Crystals
• Enhancement by polydispersity of the biaxial nematic phase in a mixture of hard rods and plates
• Phase stacking diagram of colloidal mixtures under gravity
• Free Minimization of the Fundamental Measure Theory Functional: Freezing of Parallel Hard Squares and Cubes
• Effect of polydispersity, bimodality and aspect ratio on the phase behavior of colloidal platelet suspensions
• Effect of polydispersity and soft interactions on the nematic vs. smectic phase stability in platelet suspensions

Cited by in corpus (3)

• Hard-body models of bulk liquid crystals
• Role of length-polydispersity on the phase behavior of freely-rotating hard-rectangle fluid
• Phase behaviour and correlations of parallel hard squares: From highly confined to bulk systems