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A new pH and thermo-responsive chiral hydrogel for stimulated release
Balachandran Vijai Shankar,
Published in American Chemical Society
Volume: 111
Issue: 31
Pages: 9294 - 9300
Chirality of the amphiphile to promote gelation in the given solvent medium is narrated in a new catanionic surfactant mixture from a twin-chiral, twin-tailed surfactant derived from tartaric acid and cetyltrimethylammonium bromide (CTAB). The surfactant bis(decyloxy) succinic acid (BDSA), a chiral Gemini-type surfactant with a rigid spacer, in association with CTAB formed pH and temperature responsive vesicles and hydrogels. Molecular chirality gave rise to supertwisted fibrillar hydrogels at a BDSA:CTAB molar ratio of 1:2 and in 31% water content. The hydrogels from enantiomeric BDSA were reversibly pH and irreversibly temperature responsive at pH <6.2 and at 55 °C, respectively, whereas the corresponding sodium succinates formed transparent clear gels reversible to both pH and temperature. The hydrogels were able to entrap and release model dye molecules, Rhodamine B, and Congo red, responding to thermal and pH stimuli. Circular dichroism unraveled the chiro-optical behavior of the assembled fibers, allowing monitoring of aggregation and packing. The presence and the relative configuration of the stereogenic centers in the structure of this low molecular weight gelator have been observed to be critical to form gels. The high curvature Gaussian gel network was modeled based on the chiral elastic membrane approach and the pitch angle of the Gaussian twist was estimated to be 45°. © 2007 American Chemical Society.
About the journal
JournalData powered by TypesetJournal of Physical Chemistry B
PublisherData powered by TypesetAmerican Chemical Society
Open AccessNo
Concepts (12)
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    Cationic surfactants
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    Ph effects
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    Sodium compounds
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    Water content
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    Molar ratios
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    Molecular chirality
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