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Reversibility of Thermal Transitions in Dilute Dioctadecyl‐Dimethyl‐Ammonium Bromide Vesicles
Author(s) -
Feitosa Eloi,
Adati Renata D.
Publication year - 2014
Publication title -
journal of surfactants and detergents
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.349
H-Index - 48
eISSN - 1558-9293
pISSN - 1097-3958
DOI - 10.1007/s11743-014-1581-6
Subject(s) - chemistry , differential scanning calorimetry , bromide , vesicle , ammonium bromide , transition temperature , kinetics , crystallography , calorimetry , analytical chemistry (journal) , polymer chemistry , chromatography , inorganic chemistry , thermodynamics , pulmonary surfactant , membrane , biochemistry , physics , superconductivity , quantum mechanics
Dioctadecyl‐dimethyl‐ammonium bromide (DODAB) vesicles can be characterized by their differential scanning calorimetry (DSC) thermograms comprised of two endotherms at T s ≈ 36 °C and T m ≈ 45 °C in the heating, ascribed respectively to the subgel‐to‐gel and gel‐to‐liquid crystalline transitions, and two exotherms at T ′ m ≈ 40 °C and T ′ s ≈ 16 °C in the cooling, ascribed respectively to the liquid crystalline‐to‐gel and gel‐to‐subgel transitions. It has been reported but not proved that the T m ‐transitions, the T ′ m ‐transitions, the T s ‐transitions, and the T ′ s ‐transitions are reverse to each other, displaying hystheresis Δ T m ≈ 5 °C and Δ T s ≈ 20–25 °C, respectively. By investigating the effects of the initial scanning temperature ( T i ) on the transition enthalpies (Δ H m , Δ H s , Δ H ′ m and Δ H ′ s ), we have seen that these transitions are the reverse to each other and display different kinetics.