Effect of surfactant alkyl chain length on lyotropic uniaxial to biaxial cholesteric phase transitions

Author(s)

Akpinar, Erol ^[1] ; Uygur, Nazli ^[1] ; Uyanik, Seda ^[1] ; Figueiredo Neto, Antonio Martins ^[2]

Affiliation

^[1] Abant Izzet Baysal Univ, Fac Arts & Sci, Dept Chem, TR-14030 Golkoy, Bolu - Turkey

^[2] Univ Sao Paulo, Inst Fis, Rua Matao 1371, BR-05508090 Sao Paulo, SP - Brazil

• Document type: Journal article
• Source: EUROPEAN PHYSICAL JOURNAL E; v. 42, n. 9 SEP 2019.
• Web of Science Citations: 0

Abstract

Some ionic surfactant-based lyotropic mixtures, exhibiting cholesteric phases, were prepared to investigate the effect of the surfactant alkyl chain length on a) uniaxial-to-biaxial phase transitions and b) stabilization of different cholesteric phases. Potassium alkanoates, KCx, (potassium undecanoate, KC11, potassium dodecanoate, KC12, and potassium tridecanoate, KC13) were chosen as the surfactant molecules. The lyotropic mixtures, which were composed of KCx/potassium sulfate (K2SO4)/decanol (DeOH)/water/brucine, where brucine is a chiral dopant molecule, were studied. Partial phase diagrams were constructed to show how the surfactant alkyl chain affects the phase topologies in the phase diagrams. It was observed that the presence of a longer surfactant alkyl chain in the mixture favors the stabilization of the larger discotic cholesteric, Ch(D), and cholesteric biaxial, Ch(B), phase domains. The phase transitions from the uniaxial cholesteric to biaxial cholesteric phase were shifted to lower temperatures. (AU)

• FAPESP's process: 16/24531-3 - Structural and biophysics properties of native and modified lipoproteins
• Grantee: Antonio Martins Figueiredo Neto
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 14/50983-3 - INCT 2014: complex fluids
• Grantee: Antonio Martins Figueiredo Neto
• Support Opportunities: Research Projects - Thematic Grants