Irreversible Adsorption from Solution

这个项目属于分析化学和表面化学领域，属于界面过程的子领域。这个实验项目的重点是测试最近发展的理论模型，这些模型提供了对溶液不可逆吸附的基本分子相互作用的解释。当吸附和解吸过程的动力学相当时，分子从溶液到表面的吸附被称为可逆的。在观察到不可逆吸附的系统中，脱附动力学明显慢于吸附动力学。这意味着在吸附之后，在吸附层中发生分子水平的变化；这一含义具有重要的基础和应用意义。红外和光激发发射光谱将用于研究不可逆吸附层的结构及其形成和溶解的动力学。此外，表面椭偏将用于快速动力学研究，这是跟踪表面相变从可逆到不可逆行为所必需的。研究压力和溶液条件以及底物组成对吸附行为的影响，将有助于确定这些界面过程的分子细节。这种重要但尚未被探索的不可逆吸附现象不仅对增进对界面上基本分子相互作用的理解很重要，而且对三次采油、表面润滑和磨损、光催化以及植入式假体装置与体内环境的相互作用等技术重要领域也很重要。

This project is in the area of analytical and surface chemistry and in the subfield of interfacial processes. The thrust of this experimental program is the testing of recently developed theoretical models which provide explication of the fundamental molecular interactions that underlie irreversible adsorption from solution. The adsorption of molecules from solution onto a surface is said to be reversible when the kinetics of the adsorption and desorption processes are comparable. In systems where irreversible adsorption is observed, the kinetics of desorption are significantly slower than the kinetics of adsorption. This implies that molecular-level changes take place in the adsorbed layer subsequent to adsorption; such implication has significant fundamental and applied importance. Infrared and photoexcited emission spectroscopy will be used to study both the structures of irreversibly adsorbed layers and the kinetics of their formation and dissolution. Additionally, surface ellipsometry will be employed for fast kinetic studies that are necessary to follow the surface phase change that converts reversible to irreversible behavior. Studies of the effects of pressure and solution conditions and also of substrate composition on adsorption behavior will be pursued to help to define the molecular details of these interfacial processes. This important but largely unexplored phenomenon of irreversible adsorption is important not only to an enhanced understanding of fundamental molecular interactions at interfaces, but also to technologically important areas such as tertiary oil recovery, surface lubrication and wear, photocatalysis, and the interaction of implantable prosthetic devices with their in vivo environments.