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Stress-induced birefringence in the isotropic phases of lyotropic mixtures

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Autor(es):
Fernandes, P. R. G. ; Maki, J. N. ; Goncalves, L. B. ; de Oliveira, B. F. ; Mukai, H.
Número total de Autores: 5
Tipo de documento: Artigo Científico
Fonte: PHYSICAL REVIEW E; v. 97, n. 2, p. 5-pg., 2018-02-22.
Resumo

In this work, the frequency dependence of the known mechano-optical effect which occurs in the micellar isotropic phases (I) of mixtures of potassium laurate (KL), decanol (DeOH), and water is investigated in the range from 200 mHz to 200 Hz. In order to fit the experimental data, a model of superimposed damped harmonic oscillators is proposed. In this phenomenological approach, the micelles (microscopic oscillators) interact very weakly with their neighbors. Due to shape anisotropy of the basic structures, each oscillator i (i = 1,2,3,..., N) remains in its natural oscillatory rotational movement around its axes of symmetry with a frequency omega(0i). The system will be in the resonance state when the frequency of the driving force. reaches a value near omega(0i). This phenomenological approach shows excellent agreement with the experimental data. One can find f similar to 2.5, 9.0, and 4.0 Hz as fundamental frequencies of the micellar isotropic phases I, I-1, and I-2, respectively. The different micellar isotropic phases I, I-1, and I-2 that we find in the phase diagram of the KL-DeOH-water mixture are a consequence of possible differences in the intermicellar correlation lengths. This work reinforces the possibilities of technological applications of these phases in devices such as mechanical vibration sensors. (AU)

Processo FAPESP: 14/50983-3 - INCT 2014: fluidos complexos
Beneficiário:Antonio Martins Figueiredo Neto
Modalidade de apoio: Auxílio à Pesquisa - Temático