Hydrotropes are small, short-tailed amphiphiles that strongly enhance the aqueous solubility of hydrophobic compounds otherwise sparingly soluble, after a minimum hydrotrope concentration. The hydrotropic effect of the molecules representative of all three classes of hydrotropes was examined, in terms of the solubilisation efficiency of these molecules to dissolve pyrene. Pyrene was chosen as a standard hydrophobic compound. The selected series of cationic hydrotropic compounds consisted of tetraalkylammonium chlorides, with increasing hydrophobic character, by the introduction of a -CH2- to each of the four alkyl groups, in order to make every next homologue of the series. The anionic hydrotrope series comprised of structurally related aromatic carboxylates. All of the examined hydrotropes exhibited a linear rise in the solubility of pyrene with the increase in the concentration of the hydrotrope, irrespective of the class. The hydrotropic effect of the amphiphiles of all three series, designed and examined here, was scrutinized in terms of alterations in the properties of micellar and lyotropic mesophases, of a chosen, systematic and sequenced set of non ionic surfactants, in the aqueous medium. A parallel and comparative study was made using a standard inorganic salt, NaCI. Hydrotropes displayed a demotion in the aggregation of micellar phase of nonionic surfactants compared to the growth of micelles caused by the NaCI. The mechanism was found to involve comicellisation of hydrotropes in to the nonionic micelles, The destabilization leading to fluidization of lyotropic mesophases, while preventing phase separation, of the aqueous non ionic surfactants studied, was another effect caused by all of the hydrotropes universally.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:684751 |
| Date | January 2014 |
| Creators | Naz, Asma |
| Publisher | University of Bristol |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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