Rojas OJ, Claesson PM, Muller D, Neuman RD
Escuela de Ingeniería Química, Universidad de Los Andes, Mérida, 5101, Venezuela
J Colloid Interface Sci. 1998 Sep 1;205(1):77-88. doi: 10.1006/jcis.1998.5596.
In this investigation surface force, X-ray photoelectron spectroscopy and ellipsometry techniques have been used to study the adsorption of a low-charge-density cationic polyelectrolyte on negatively charged surfaces. It is shown that the low cationicity of this polyelectrolyte induces an adsorption behavior which is limited by steric factors rather than by the substrate surface charge or potential. It is also established that an increase in ionic strength of the solution results in desorption of the polyelectrolyte accompanied by an increase in layer thickness. This phenomenon is typical of a screening-reduced adsorption regime where electrostatic interactions predominate in the adsorption process. An increase in layer thickness most often occurs as a result of an increased adsorbed amount. Here, however, the increase in layer thickness occurs despite a reduction in the adsorbed amount. This can be understood as resulting from a reduced polyelectrolyte-surface affinity and a swelling of the adsorbed layer. Finally, it is demonstrated that the employed techniques complement each other and reveal new information on the interaction forces and conformation of polyelectrolytes at the solid-liquid interface. Copyright 1998 Academic Press.
在本研究中，采用表面力、X射线光电子能谱和椭偏测量技术研究了低电荷密度阳离子聚电解质在带负电表面上的吸附。结果表明，该聚电解质的低阳离子性导致其吸附行为受空间位阻因素限制，而非受基底表面电荷或电位的限制。还证实，溶液离子强度的增加会导致聚电解质解吸，同时层厚度增加。这种现象是典型的屏蔽减少吸附机制，其中静电相互作用在吸附过程中占主导地位。层厚度的增加通常是由于吸附量增加所致。然而，在此处，尽管吸附量减少，但层厚度仍增加。这可以理解为是由于聚电解质与表面的亲和力降低以及吸附层膨胀所致。最后，证明了所采用的技术相互补充，并揭示了关于聚电解质在固液界面处的相互作用力和构象的新信息。版权所有1998年学术出版社。
