Department of Forest Biomaterials, North Carolina State University, Campus Box 8005, Raleigh, North Carolina 27695-8005, USA.
J Phys Chem B. 2010 Jan 21;114(2):719-27. doi: 10.1021/jp909047t.
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.
研究了水溶液中聚两性电解质的性质与其在硅胶和纤维素表面上的吸附行为之间的关系。使用涂覆有硅胶和纤维素的石英谐振器的石英晶体微天平研究了四种具有不同电荷密度但具有相同正、负片段名义比的聚两性电解质和两种结构相似的聚电解质（聚酸和聚碱）。通过测量各自谐振器的频率（Deltaf）和能量耗散（DeltaD）的变化，确定了吸附层的时间分辨质量和刚性（或粘弹性）。因此，可以阐明吸附的动力学和程度以及吸附大分子的构象变化。固体表面的电荷性质在研究的聚两性电解质的吸附中起着关键作用，这可以通过表面在界面处极化聚两性电解质的能力来解释。在相同的实验条件下，聚两性电解质具有较高的名义电荷密度，在界面附近发生相分离，形成柔软、耗散和松散结合的层。在纤维素基质的情况下，吸附受到限制，静电和极化效应被认为不太重要。
