Smectic A: cholesteric phase transition investigated by small angle X-ray diffraction and viscosity measurements

We have studied the in influence of the mean molecular length on the nature of the cholesteric (N*) – smectic A (A) liquid crystal phase transition for thermotropic compounds of cholesteryl myristate (C14), cholesteryl nonanoate (C9), and binary mixtures of C14 – C9 and cholesteryl caproate (C6) pha...

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Bibliographic Details
Published inBrazilian journal of physics Vol. 32; no. 2b; pp. 495 - 500
Main Authors Duarte, E. L., Itri, R., Sampaio, A. R., Simões, M., Palangana, A. J.
Format Journal Article
LanguageEnglish
Spanish
Portuguese
Published Sociedade Brasileira de Física 01.06.2002
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Summary:We have studied the in influence of the mean molecular length on the nature of the cholesteric (N*) – smectic A (A) liquid crystal phase transition for thermotropic compounds of cholesteryl myristate (C14), cholesteryl nonanoate (C9), and binary mixtures of C14 – C9 and cholesteryl caproate (C6) phase (dA), the mean molecular length ( ) in the N* domain, and the correlation length (epsilon), as well as changes along the N* – A phase transition, were determined from the X-ray diffraction data. The results show a decrease in A phase domain and an expansion of the N* – domain as the mean molecular length is diminished. Such effect induces a second order A – N* phase transition for a particular mixture of 63.1 mol% of C9 and 36.9 mol% of C6, evidenced by viscosity measurements in good agreement with previous density data.
ISSN:0103-9733
1678-4448
1678-4448
DOI:10.1590/S0103-97332002000300007