The Interaction Between N-Isopropylacrylamide-Acrylic Acid-Ethyl Methacrylate Thermosensitive Polymers and Cationic Surfactants
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Data
2009-01-01
Autores
de Oliveira Tiera, Vera Aparecida [UNESP]
Tiera, Marcio Jose
Blaz Vieira, Neide Aparecida
do Amaral, Bruno Rochetti
Pires, Rogerio Zambelli
Título da Revista
ISSN da Revista
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Editor
Taylor & Francis Inc
Resumo
The interaction between cationic surfactants and isopropylacrylamide-acrylic acid-ethyl methacrylate (IPA:AA:EMA) terpolymers has been investigated using steady-state fluorescence and spectrophotometric measurements to assess the effect of the polymer composition on the aggregation process and terpolymers' thermosensitivities. Micropolarity studies using pyrene show that the interaction of cationic surfactants with IPA:AA:EMA terpolymers occurs at surfactant concentrations much smaller than that observed for the pure surfactant in aqueous solution. The critical aggregation concentration (CAC) values decrease with both the hydrocarbon length of the surfactant and the content of ethyl methacrylate. These results were interpreted as a manifestation of the increasing contribution of attractive hydrophobic and electrostatic forces between negatively charged polymer chains and positively charged surfactant molecules. The increase of ethyl methacrylate in the copolymers lowers the CAC due to the larger hydrophobic character of the polymer backbone. The cloud point determination reveals that the lower critical solution temperatures (LCST) depend strongly on the copolymer composition and surfactant nature. The binding of surfactants molecules to the polymer chain screens the electrostatic repulsion between the carboxylic groups inducing a conformational transition and the dehydration of the polymer chain.
Descrição
Palavras-chave
Cationic surfactants, Fluorescence, isopropylacrylamide, polyelectrolyte, thermosensitive
Como citar
Journal of Dispersion Science and Technology. Philadelphia: Taylor & Francis Inc, v. 30, n. 8, p. 1121-1128, 2009.