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vol.48 número1THEORETICAL STUDY OF THE OPIOID RECEPTOR SELECTIVITY OF SOME 7-ARYLIDENENALTREXONESADVANCES IN THE UNDERSTANDING OF THE DISSOLUTION MECHANISM OF CELLULOSE IN DMAc/LiCl índice de autoresíndice de assuntospesquisa de artigos
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Journal of the Chilean Chemical Society

versão On-line ISSN 0717-9707

Resumo

BARRAZA, RAUL G.; OLEA, ANDRES F.; FUENTES, IRMA  e  MARTINEZ, FRANCISCO. ELECTRICAL CONDUCTIVITY OF HYDROPHOBICALLY MODIFIED POLYELECTROLYTES IN METHANOL/WATER SOLUTION. J. Chil. Chem. Soc. [online]. 2003, vol.48, n.1, pp.67-71. ISSN 0717-9707.  http://dx.doi.org/10.4067/S0717-97072003000100012.

Measurements of the electrical equivalent conductivity of potassium salts of poly(maleic acid-co-1-olefins), PA-nK2 with n = 12, 18 has been carried out in methanol-water mixtures in the whole range of composition. The relative interaction parameter f*, was determined as a function of the mole fraction of methanol. The values of f* do not follow the same tendency of the limiting equivalent conductivity. This unusual behavior was rationalized in terms of a methanol-induced conformational transition that takes the polymer chain from a compact to an expanded structure. As a consequence of this transition the average charge distance in the polyion increases with increasing mole fraction of methanol. This brings about a decrease of the linear charge density parameter, and therefore an increase of the fraction of polymer charges dissociated from their counterions. The existence of the conformational transition of the PA-nK2 copolymers was confirmed through fluorescence probing experiments

Palavras-chave : Polyelectrolytes; electrical conductivity; counterion condensation; conformational transition.

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