Hydrophobic Polyelectrolytes in Better Polar Solvent. Structure and Chain Conformation As Seen by SAXS and SANS

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• 作者：Wafa Essafi ; Marie-Noelle Spiteri ; Claudine Williams ; Franois Boue
• 刊名：Macromolecules
• 出版年：2009
• 出版时间：December 22, 2009
• 年：2009
• 卷：42
• 期：24
• 页码：9568-9580
• 全文大小：1147K
• 年卷期：v.42,no.24(December 22, 2009)
• ISSN：1520-5835

文摘

We demonstrate the influence of solvent quality on the structure of the semidilute solution of a hydrophobic polyelectrolyte, partially sulfonated polystyrenesulfonate. Two solvents are used: (i) one mixture of water and an organic solvent, THF, which is also slightly polar; (ii) DMSO, a polar organic solvent. In case i, it is shown by SAXS study that the structure, namely the scattering from all chains, characterized by a maximum (“polyelectrolyte peak”), of the aqueous hydrophobic polyelectrolyte solutions (PSS) depends on the solvent quality through the added amount of organic solvent THF. This dependence is more pronounced when the sulfonation rate is low (more hydrophobic polyelectrolyte). It is proposed that when THF is added, the chain conformation evolves from the pearl-necklace shape already reported in pure water toward the conformation in pure water for fully sulfonated PSS, which is stringlike as also reported previously. On the contrary, for a hydrophilic polyelectrolyte, AMAMPS, no evolution occurs with added THF in the aqueous solution. In case ii, it is shown directly by SANS study that PSS can behave as a classical solvophilic polyelectrolyte when dissolved in an organic polar solvent such as DMSO: the structure (total scattering) as well as the form factor (single chain scattering measured by SANS using the zero average contrast method) of the PSS chains is independent of the charge content, in agreement with Manning condensation, and identical to the one of a fully charged PSS chain in pure water, which has a classical polyelectrolyte behavior in the semidilute regime.