Physicochemical Properties of Methylcellulose and Dodecyltrimethylammonium Bromide in Aqueous Medium

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• 作者：Marcos A. Villetti ; Clara I. D. Bica ; Irene T. S. Garcia ; Fabiano V. Pereira ; Francieli I. Ziembowicz ; Carmen L. Kloster ; Cristiano Giacomelli
• 刊名：Journal of Physical Chemistry B
• 出版年：2011
• 出版时间：May 19, 2011
• 年：2011
• 卷：115
• 期：19
• 页码：5868-5876
• 全文大小：948K
• 年卷期：v.115,no.19(May 19, 2011)
• ISSN：1520-5207

文摘

Interactions between uncharged polymers and cationic surfactants are considered weaker than interactions with the anionic analogues. This work describes the binding occurring between methylcellulose (MC) and the cationic surfactant DTAB in aqueous medium. In the absence of salt, MC鈥揇TAB exhibits a maximum in hydrodynamic radius, R_h,slow, with the increase in the surfactant concentration. Otherwise, in presence of salt the MC鈥揇TAB system shows only a linear increase of R_h,slow. CAC is lower than the CMC, which is taken as an evidence of binding between the cationic surfactant and neutral polymer that induces the aggregation process. Static light scattering, rheology and micro-DSC results highlight the hydrophobic MC鈥揇TAB association. Salt-out and the salt-in effects were observed in presence of DTAB, with a clear transition at concentration values close to the CMC, as judged from rheological and micro DSC measurements. Indeed, DTAB affects both the pattern of the sol鈥揼el transition and the gel strength.