Details

Autor(en) / Beteiligte

• Steck, Katja
• Schmidt, Claudia
• Stubenrauch, Cosima

Titel

The Twofold Role of 12-Hydroxyoctadecanoic Acid (12-HOA) in a Ternary Water-Surfactant-12-HOA System: Gelator and Co-Surfactant

Ist Teil von

• Gels, 2018-09, Vol.4 (3), p.78

Ort / Verlag

Switzerland: MDPI AG

Erscheinungsjahr

2018

Link zum Volltext

Quelle

EZB Free E-Journals

Beschreibungen/Notizen

• Gelled lyotropic liquid crystals can be formed by adding a gelator to a mixture of surfactant and solvent. If the gel network and the liquid-crystalline phase coexist without influencing each other, the self-assembly is called orthogonal. In this study, the influence of the organogelator 12-hydroxyoctadecanoic acid (12-HOA) on the lamellar and hexagonal liquid crystalline phases of the binary system H₂O⁻C E₇ (heptaethylene glycol monododecyl ether) is investigated. More precisely, we added 12-HOA at mass fractions from 0.015 to 0.05 and studied the resulting phase diagram of the system H₂O⁻C E₇ by visual observation of birefringence and by ²H NMR spectroscopy. In addition, the dynamic shear moduli of the samples were measured in order to examine their gel character. The results show that 12-HOA is partly acting as co-surfactant, manifested by the destabilization of the hexagonal phase and the stabilization of the lamellar phase. The higher the total surfactant concentration, the more 12-HOA is incorporated in the surfactant layer. Accordingly, its gelation capacity is substantially reduced in the surfactant solution compared to the system 12-HOA⁻ -decane, and large amounts of gelator are required for gels to form, especially in the lamellar phase.