Formation of Polyelectrolyte Multilayers by Flexible and Semiflexible Chains

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• 作者：Bo Wu ; Chunliang Li ; Haiyang Yang ; Guangming Liu ; Guangzhao Zhang
• 刊名：The Journal of Physical Chemistry B
• 出版年：2012
• 出版时间：March 15, 2012
• 年：2012
• 卷：116
• 期：10
• 页码：3106-3114
• 全文大小：557K
• 年卷期：v.116,no.10(March 15, 2012)
• ISSN：1520-5207

文摘

Poly(sodium 4-styrene sulfonate) (PSS) and poly(diallyldimethylammonium chloride) (PDDA) are flexible polyelectrolytes, whereas sulfated chitosan (SC) and cationic guar gum (CGG) are semiflexible polyelectrolytes. By use of a quartz crystal microbalance with dissipation (QCM-D), a zeta potential analyzer (ZPA), and atomic force microscopy (AFM), we have investigated the growth of PSS/PDDA, PSS/CGG, SC/PDDA, and SC/CGG multilayers as a function of NaCl concentration (C_NaCl). For the same layer number, the changes of frequency (鈭捨?i>f) and dissipation (螖D) regarding PSS/PDDA multilayer increase with C_NaCl, whereas 鈭捨?i>f and 螖D for SC/CGG multilayer increase at C_NaCl < 0.1 M and decrease at C_NaCl > 0.1 M as C_NaCl increases. In the cases of PSS/CGG and SC/PDDA multilayer, for the same layer number, 鈭捨?i>f and 螖D increase with C_NaCl in the range of C_NaCl < 0.5 M, and they decrease with the increasing C_NaCl in the case of SC/PDDA multilayer but slightly change for the PSS/CGG multilayer at C_NaCl > 0.5 M. QCM-D studies indicate that the growth of multilayers as a function of salt concentration is determined by the delicate balance between the weakening of electrostatic repulsion between identically charged groups and the decrease of electrostatic attraction between neighboring layers. ZPA and AFM measurements demonstrate that the extent of surface charge overcompensation and the surface morphology of the multilayers are controlled by the chain conformation.