Utilize este identificador para referenciar este registo: http://hdl.handle.net/10400.21/530
Título: Reversible Photorheology in Solutions of Cetyltrimethylammonium Bromide, Salicylic Acid, and trans-2,4,4 '-Trihydroxychalcone
Autor: Pereira, M.
Leal, Catarina Marques Mendes Almeida da Rosa
Parola, A. J.
Scheven, U. M.
Palavras-chave: Concentrated Polimer Systems
Rheological Behavior
Surfactant Solutions
Dynamics
Micelles
Motion
Light
Data: 16-Nov-2010
Editora: Amer Chemical Soc
Citação: Pereira M, Leal C, Parola A, Scheven U.Reversible Photorheology in Solutions of Cetyltrimethylammonium Bromide, Salicylic Acid, and trans-2,4,4 '-Trihydroxychalcone . Langmuir. 2010; 26 (22): 16715-16721.
Relatório da Série N.º: 22;
Resumo: We show photorheology in aqueous solutions of weakly entangled wormlike micelles prepared with cetyltrimethylammonium bromide (CTAB), salicylic acid (HSal), and dilute amounts of the photochromic multistate compound trans-2,4,4'-trihydroxychalcone (Ct). Different chemical species of Ct are associated with different colorations and propensities to reside within or outside CTAB micelles. A light-induced transfer between the intra- and intermicellar space is used to alter the mean length of wormlike micelles and hence the rheological properties of the fluid, studied in steady-state shear Bow and in dynamic rheological measurements. Light-induced changes of fluid rheology are reversible by a the relaxation process. at relaxation rates which depend on pH and which are consistent with photochromic reversion rates measured by UV-vis absorption spectroscopy. Parameterizing viscoelostic rheological states by their effective relaxation time tau(c) and corresponding response modulus G(c), we find the light and dark states of the system to fall onto a characteristic state curve defined by comparable experiments conducted without photosensitive components. These reference experiments were prepared with the same concentration of CTAB, but different concentrations of HSal or sodium salicylote (NaSal), and tested at different temperatures.
Peer review: yes
URI: http://hdl.handle.net/10400.21/530
ISSN: 0743-7463
Aparece nas colecções:ISEL - Eng. Quim. Biol. - Artigos



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