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The interactions between surfactant and water were studied thermoanalytically focusing on the lyotropic liquid crystalline and microemulsion region in four ternary systems containing Cremophor EL and Cremophor RH40 as surfactants, neutral oil and isopropyl myristate as oily components. Subzero temperature DSC (SZT-DSC) measurements were carried out to determine the quantity of the bound water forming a hydration layer in surfactant microstructures, and the amount of free water, which has physico-chemical properties not much different from those of pure water. The variation of the surfactant:bound water ratio in the function of water concentration was also investigated. Phase changes detected by the SZT-DSC measurements were confirmed by polarization-microscopic and rheological investigations.

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Rubidium and lithium butanoates binary phase diagram

Formation of a stable lyotropic liquid crystal phase and two mixed salts

Journal of Thermal Analysis and Calorimetry
Authors: F. Martínez Casado, M. Ramos Riesco, and J. Cheda

Abstract  

The temperature and enthalpy vs. composition diagrams of the binary system [xC3H7CO2Li+(1–x)C3H7CO2Rb], where x=mole fraction, were determined by differential scanning calorimetry (DSC). This binary systems displays the formation of two mixed salts with a composition 1:1 and 1:2, which melt incongruently at T fus=590.5 K, with Δfus H m=11.6 kJ mol–1, and congruently at T fus=614.5 K, with Δfus H m=20.2 kJ mol–1, respectively. The phase diagram also presents an ionic liquid-crystalline phase in a wide temperature range: 95 K.

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Abstract  

We studied the phase transition temperatures of a series of amphiphilic D-xylopyranose and D-xylofuranose derivatives in which the lipophilic part is an alkyl chain R (n-CnH2n+1), regiospecifically linked to D-xylose, at different positions, by Z which is an atom or a functional group (O, S, O–(CH2)3–S). The alkyl chain was moved from the C-1 to the C-5 position in the xylose moiety, thereby allowing us to compare directly the phase transition temperatures of the individual materials. These compounds give thermotropic and/or lyotropic liquid crystals. In some cases, we also observed solid–solid phase transitions.

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Journal of Thermal Analysis and Calorimetry
Authors: Eszter Csizmazia, Mária Budai-Szűcs, István Erős, Zsolt Makai, Piroska Szabó-Révész, Gábor Varju, and Erzsébet Csányi

Abstract  

Our aim was to develop potential dermal drug delivery systems (DDSs) with a good and lasting moisturizing effect. Lyotropic liquid crystals (LLCs), gel-emulsions and hydrogels were investigated by means of thermogravimetry, which can give information about the structure of these preparations, and we could study the water binding mechanisms indirectly in them. We found that the preparations with a complex structure and strong water bonds hydrate the skin well and lastingly by in vivo tests. Since the thermoanalytical results correlate with the in vivo test results, this method could be suited for predicting the moisturizing effect of the vehicles and provide the possibility to select the potential semisolid DDSs for in vivo tests cost and time effectively.

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SBA-15 silicas containing sucrose

Chemical, structural, and thermal studies

Journal of Thermal Analysis and Calorimetry
Authors: M. Barczak, M. Oszust-Cieniuch, P. Borowski, Z. Fekner, and E. Zięba

structures . J Am Chem Soc 120 : 6024 – 6036 10.1021/ja974025i . 9. Goltner , CG , Henke , S , Weissenberger , MC , Antonietti , M 1998 Mesoporous silica from lyotropic liquid crystal

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Journal of Thermal Analysis and Calorimetry
Authors: Taís Vanessa Gabbay Alves, Eraldo José Madureira Tavares, Fauze Ahmad Aouada, Charles Alberto Brito Negrão, Marcos Enê Chaves Oliveira, Anivaldo Pereira Duarte Júnior, Carlos Emmerson Ferreira da Costa, José Otávio Carréra Silva Júnior, and Roseane Maria Ribeiro Costa

, Rubira , AF , Muniz , EC , Fernandes , PRG , Mukai , H , et al. Birefringent hydrogels based on PAAm and lyotropic liquid crystal: optical, morphological and hydrophilic characterization . Eur Polym J . 2006 ; 42 : 10 2781 – 2790 . 10.1016/j

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