Effect of charge asymmetry on adsorption and phase separation of polyampholytes on silica and cellulose surfaces.
Effect of charge asymmetry on adsorption and phase separation of polyampholytes on silica and cellulose surfaces.
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DOI：
10.1021/jp909047t
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发表时间：
2010-01
期刊：
影响因子：
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通讯作者：
Junlong Song;T. Yamagushi;D. J. Silva;M. Hubbe;O. Rojas
中科院分区：
文献类型：
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作者：
Junlong Song;T. Yamagushi;D. J. Silva;M. Hubbe;O. Rojas
研究了水溶液中两性聚合物的性质与其在二氧化硅和纤维素表面的吸附行为之间的关系。用石英晶体微重法研究了四种具有不同电荷密度但具有相同标称正负链段比的聚电解质和两种结构相似的聚电解质(一种聚酸和一种聚碱)。吸附层的时间分辨质量和刚性(或粘弹性)由相应谐振器的频率位移(Deltaf)和能量耗散(DeltaD)确定。因此，阐明吸附的动力学和程度，以及吸附的大分子的构象变化是可能的。固体表面的电荷性质对所研究的聚两性阳离子的吸附起着至关重要的作用，这可以用表面极化界面上的聚两性阳离子的能力来解释。在相同的实验条件下，聚两性离子在界面附近有较高的标称电荷密度相分离，形成一层柔软的、耗散的、松散的结合层。在纤维素基质的情况下，吸附是有限的，静电和极化效应被认为不那么显著。
The relation between the properties of polyampholytes in aqueous solution and their adsorption behaviors on silica and cellulose surfaces was investigated. Four polyampholytes carrying different charge densities but with the same nominal ratio of positive to negative segments and two structurally similar polyelectrolytes (a polyacid and a polybase) were investigated by using quartz crystal microgravimetry using silica-coated and cellulose-coated quartz resonators. Time-resolved mass and rigidity (or viscoelasticity) of the adsorbed layer was determined from the shifts in frequency (Deltaf) and energy dissipation (DeltaD) of the respective resonator. Therefore, elucidation of the dynamics and extent of adsorption, as well as the conformational changes of the adsorbed macromolecules, were possible. The charge properties of the solid surface played a crucial role in the adsorption of the studied polyampholytes, which was explained by the capability of the surface to polarize the polyampholyte at the interface. Under the same experimental conditions, the polyampholytes had a higher nominal charge density phase-separated near the interface, producing a soft, dissipative, and loosely bound layer. In the case of cellulose substrates, where adsorption was limited, electrostatic and polarization effects were concluded to be less significant.