Influence of a random field on particle fractionation and solidification in liquid-crystal colloid mixtures

Vlad Dumitru Popa-Nita (Author), Paul van der Schoot (Author), Samo Kralj (Author)

Abstract

The influence of a random-anisotropy (RA) type disorder on the phase separation of nematogen-colloid mixtures is studied theoretically by combiningthe phenomenological Landau-de Gennes, Carnahan-Starling, and hard-sphere crystal theories. We assume that the colloids enforce the RA disorder on the surrounding thermotropic liquid-crystal (LC) molecules. We adopt the Imry-Ma argument according to which the lower-temperature phase exhibits a domain-type pattern. The colloids impose a finite degree of orientational ordering even in the isotropic (paranematic) phase. In the ordered phase they give rise to a domain-type structure, resulting in the distorted nematic (speronematic) phase. The RA field opposes the phase separation tendency. With increasing disorder the difference between the paranematic and speronematic ordering decreases. Consequently there is a critical disorder, above which both phases become identical from the orientation point of view, but have different concentrations of colloids. We have also estimated another characteristic value of disorder above which the isotropic phase can exist only in a liquid state, the crystal phase being suppressed completely.

Keywords

tekoči kristali;prehodi;segregacija;mešanje;naključna polja;ne zaključna dela;liquid crystals;transitions;segregation;mixing;random fields;solidification;complex fluids;

Data

Language:	English
Year of publishing:	2006
Typology:	1.01 - Original Scientific Article
Organization:	UM PEF - Faculty of Education
UDC:	539.2
COBISS:	15106824
ISSN:	1292-8941
Views:	1379
Downloads:	90
Average score:	0 (0 votes)
Metadata:

Other data

Secondary language:	Slovenian
Secondary keywords:	tekoči kristali;prehodi;segregacija;mešanje;naključna polja;
URN:	URN:SI:UM:
Type (COBISS):	Article
Pages:	str. 189-197
Issue:	21
Chronology:	2006
ID:	8724205