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| Author(s): |
Juliana da Silva Bernardes
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Campinas, SP. |
| Institution: | Universidade Estadual de Campinas (UNICAMP). Instituto de Química |
| Defense date: | 2008-09-09 |
| Examining board members: |
Watson Loh;
Harry Westfahl Junior;
Elizabeth Pinheiro Gomes Areas;
Edvaldo Sabadini;
Fred Yukio Fujiwara
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| Advisor: | Watson Loh |
| Abstract | |
Association between charged polymers and oppositely charged surfactants in aqueous solutions may lead to phase separation forming a concentrated phase rich in polyions and surfactant ions, and a more dilute phase, which mostly contains simple ions. The concentrated phases may display a variety of supramolecular structures with diverse and interesting features due to self-assembling properties of these systems, which have found applications in the field of controlled drug delivery and in templating the synthesis of materials with tailored geometries. A complete description of the phase equilibrium in these systems is quite demanding, because addition of polyelectrolyte and oppositely charged surfactant to water leads to the formation of several components, however it is possible to reduce the number of the components by the preparation of the pure complex-salt, which allows to analyze the phase equilibrium in a controlled manner. In this work the phase behavior of complex salts formed by the surfactant ion hexadecyltrimethylammonium (CTA) and the polyacrylate (PA) in water and with different organic solvents were investigated. Three principal effects were analyzed: the effect of the organic solvent nature; the effect of n-alcohol carbon chain length and the effect of the polyelectrolyte hidrophibicity. The obtained results revealed that the organic solvent nature has a strong influence in the structure assumed by the complex salt. From the general analysis, systems containing co-surfactants (n-alcohols) a predominance of lamellar structures was observed, and in systems containing p-xylene and ciclohexane a predominance of hexagonal structures was detected. The polyelectrolyte hidrophobicity did not display significant changes in the obtained phase diagrams. (AU) | |