Segregation in Like-Charged Polyelectrolyte鈥揝urfactant Mixtures Can Be Precisely Tuned via Manipulation of the Surfactant Mass Ratio

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• 作者：Peter W. Wills ; Sonia G. Lopez ; Jocelyn Burr ; Pablo Taboada ; Stephen G. Yeates
• 刊名：Langmuir
• 出版年：2013
• 出版时间：April 9, 2013
• 年：2013
• 卷：29
• 期：14
• 页码：4434-4440
• 全文大小：329K
• 年卷期：v.29,no.14(April 9, 2013)
• ISSN：1520-5827

文摘

In this study, we consider segregative phase separation in aqueous mixtures of quaternary ammonium surfactants didecyldimethylammonium chloride (DDQ) and alkyl (C12, 70%; C14 30%) dimethyl benzyl ammonium chloride (BAC) upon the addition of poly(diallyldimethylammonium) chloride (pDADMAC) as a function of both concentration and molecular weight. The nature of the surfactant type is dominant in determining the concentration at which separation into an upper essentially surfactant-rich phase and lower polyelectrolyte-rich phase is observed. However, for high-molecular-weight pDADMAC there is a clear indication of an additional depletion flocculation effect. When the BAC/DDQ ratio is tuned, the segregative phase separation point can be precisely controlled. We propose a phase separation mechanism for like-charged quaternary ammonium polyelectrolyte/surfactant/water mixtures induced by a reduction in the ionic atmosphere around the surfactant headgroup and possible ion pair formation. An additional polyelectrolyte-induced depletion flocculation effect was also observed.