Sedeva Iliana G, Fornasiero Daniel, Ralston John, Beattie David A
Ian Wark Research Institute, University of South Australia, Mawson Lakes, Adelaide, SA 5095, Australia.
Langmuir. 2009 Apr 21;25(8):4514-21. doi: 10.1021/la803838k.
The adsorption of a modified polyacrylamide on gold surfaces coated with varying proportions of -CH3- and -OH-terminated alkanethiols (producing substrates of varying hydrophobicity: thetac=75, 98, and 119 degrees), was investigated using quartz crystal microbalance with dissipation (QCM-D), tapping-mode atomic force microscopy (TM-AFM), and captive bubble contact angle measurements. The QCM-D data for the polymer adsorbing on the different substrates indicates that the polymer adsorbs faster and to a greater extent on surfaces with higher hydrophobicity. Dissipation data from the QCM-D suggests that the adsorbed polymer undergoes a conformational change when adsorbing onto the substrates of higher hydrophobicity, forming a less rigid extended layer as the adsorption progresses toward the maximum adsorbed amount. AFM imaging of the adsorbed layer illustrates that the polymer layer is incomplete on all three substrates, and that the underlying substrate hydrophobicity has a role in determining the morphology (distribution, coverage, and thickness) of the adsorbed layer. Contact angle measurements of the polymer-coated substrates show variation in the ability of the polymer to reduce the hydrophobicity of the substrates. The role of coverage and distribution of adsorbed polymer on the surface hydrophobicity reduction is discussed.
使用带耗散监测的石英晶体微天平(QCM-D)、轻敲模式原子力显微镜(TM-AFM)和俘获气泡接触角测量,研究了一种改性聚丙烯酰胺在涂覆有不同比例的 -CH3- 和 -OH 封端的链烷硫醇(产生不同疏水性的基底:接触角分别为 75、98 和 119 度)的金表面上的吸附情况。聚合物吸附在不同基底上的 QCM-D 数据表明,聚合物在疏水性较高的表面上吸附得更快且程度更大。QCM-D 的耗散数据表明,吸附的聚合物在吸附到疏水性较高的基底上时会发生构象变化,随着吸附量向最大吸附量推进,形成刚性较小的伸展层。吸附层的 AFM 成像表明,聚合物层在所有三种基底上都不完整,并且基底的疏水性在决定吸附层的形态(分布、覆盖率和厚度)方面发挥作用。对涂覆聚合物的基底进行的接触角测量显示,聚合物降低基底疏水性的能力存在差异。讨论了吸附聚合物的覆盖率和分布对表面疏水性降低的作用。