Smooth Model Surfaces from Lignin Derivatives. II. Adsorption of Polyelectrolytes and PECs Monitored by QCM-D

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• 作者：Magnus Norgren ; Linda Gä ; rdlund ; Shannon M. Notley ; Myat Htun ; Lars Wå ; gberg
• 刊名：Langmuir
• 出版年：2007
• 出版时间：March 27, 2007
• 年：2007
• 卷：23
• 期：7
• 页码：3737 - 3743
• 全文大小：285K
• 年卷期：v.23,no.7(March 27, 2007)
• ISSN：1520-5827

文摘

For the first time to the knowledge of the authors, well-defined and stable lignin model surfaces have been utilizedas substrates in polyelectrolyte adsorption studies. The adsorption of polyallylamine (PAH), poly(acrylic acid) (PAA),and polyelectrolyte complexes (PECs) was monitored using quartz crystal microgravimetry with dissipation (QCM-D). The PECs were prepared by mixing PAH and PAA at different ratios and sequences, creating both cationic andanionic PECs with different charge levels. The adsorption experiments were performed in 1 and 10 mM sodiumchloride solutions at pH 5 and 7.5. The highest adsorption of PAH and cationic PECs was found at pH 7.5, wherethe slightly negatively charged nature of the lignin substrate is more pronounced, governing electrostatic attractionof oppositely charged polymeric substances. An increase in the adsorption was further found when the electrolyteconcentration was increased. In comparison, both PAA and the anionic PEC showed remarkably high adsorption tothe lignin model film. The adsorption of PAA was further studied on silica and was found to be relatively low evenat high electrolyte concentrations. This indicated that the high PAA adsorption on the lignin films was not inducedby a decreased solubility of the anionic polyelectrolyte. The high levels of adsorption on lignin model surfaces foundboth for PAA and the anionic PAA-PAH polyelectrolyte complex points to the presence of strong nonionic interactionsin these systems.