Studies of domain size of hexagonal liquid crystals in C12EO8/water/alcohol systems

Citation
A. Kumar et al., Studies of domain size of hexagonal liquid crystals in C12EO8/water/alcohol systems, LANGMUIR, 17(23), 2001, pp. 7245-7250
Citations number
19
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Physical Chemistry/Chemical Physics
Journal title
LANGMUIR
ISSN journal
0743-7463 → ACNP
Volume
17
Issue
23
Year of publication
2001
Pages
7245 - 7250
Database
ISI
SICI code
0743-7463(20011113)17:23<7245:SODSOH>2.0.ZU;2-1
Abstract
The broadening of the most intense lines observed in the X-ray diffraction patterns has been used to determine the domain sizes of hexagonal liquid cr ystals in C12EO8/water/alcohol systems. A linear "master" relationship betw een the sizes and the distance to the isotropic phase-transition boundary l ine (H-1 - W-m) was observed as the temperature, surfactant, and glycerol v olume fractions were varied. This linear relationship is interpreted as the feature of a "glassy" state formed by the crystallites, which grow until t heir glass-transition temperature is attained. The master relationship indi cates that both temperature and volume fraction induce the glass transition , hindering a further growth of the crystal domains. A fractal dimension cl ose to one for these cylindrical domains is obtained, and an estimation of the number of bounded cylinders inside a domain has been made. For systems containing propylene glycol and propanol, the observed increase in domain s ize on approaching the phase boundary is much larger than for glycerol syst ems, which seems to be related to the different influence of the alcohols o n the surfactant aggregation and its structure, as it was previously report ed for these alcohols. A large increase of the domain sizes by aging the sa mples, as it is usually observed for common glassy systems, is also reporte d.