Formation Kinetics of Tethered Nanolayers: Real-Time Studies with Model Polymers

美国肯塔基州林恩大学的CTS-9911181系留聚合物层为裁剪固体表面和由它们制成的界面提供了一种独特的途径。对系留聚合物的化学结构和结构的精确控制，以及对其分子量、分散性和表面附着密度的精确控制，提供了同样精确地控制层的物理化学特性从而控制固体表面性能的可能性。这种精确控制的层在其他领域具有巨大的潜在价值，包括防腐、摩擦和磨损控制、生物污垢控制和废物净化。要构建具有特定应用所需的确切特性的系留层，科学家或工程师必须能够精确地操纵系留过程。要做到这一点，必须了解成层的动力学和热力学，并将其置于实验控制之下。然而，由于a)过程涉及多相反应，以及b)聚合物链被附着在过程中变化的表面上，使得系链过程变得复杂。此外，直到最近，还没有一种方便的方法来监测系留层的形成动力学。到目前为止，这些复杂性和困难阻碍了对系留过程的基于理解的控制。在这个项目中，将根据系留反应的特定化学和物理特征来探索控制层形成的动力学和热力学因素。这些因素包括聚合物相对分子质量、聚合物结构和端基-表面相互作用。为此，将通过活性阴离子聚合来合成具有广泛不同聚合物结构、相对分子质量和链段结构的模型聚合物。作为自变量的其他变量是温度、浓度、溶剂(以及聚合物主链链段和溶剂之间的相互作用)、固体表面上反应中心的化学(从而反应中心和聚合物链的末端官能团之间的相互作用)，以及固体表面的能量学。模型聚合物在不同条件下与固体表面的连接反应将通过一种新开发的基于尺寸排除层析的实时方法进行监测。上述研究获得的数据和出现的原理将导致对连接动力学的全面描述和对影响过程的热力学因素的评估。在此基础上，我们将发展出一套逻辑准则和一个普遍适用的系链动力学数学模型，可用于对系链层结构的经验控制操作。

ABSTRACT CTS-9911181 Lynn Penn, U. of Kentucky Tethered polymer layers provide a unique avenue for tailoring solid surfaces and the interfaces made from them. Precise control of not only the chemical structure and architecture of the tethered polymer, but also of its molecular weight, dispersity, and surface attachment density offers the possibility of similarly precise control of the physicochemical characteristics of the layer and therefore of the performance of the solid surface. Such precisely controlled layers have great potential value in additional areas, including corrosion prevention, friction and wear control, biofouling control, and waste stream purificationTo construct a tethered layer that has the exact characteristics needed for a particular application, the scientist or engineer must be able to manipulate the tethering process with precision. For this to be done, the kinetics and thermodynamics of layer formation must be understood and brought under experimental control. However, the tethering process is made complex by the facts that a) the process involves heterogeneous phase reactions and b) the polymer chains are being attached to a surface that is changing during the process. Furthermore, until recently, there has been no convenient way to monitor the kinetics of formation of a tethered layer. These complexities and difficulties have prevented understanding-based control of the tethering process until the present time.In this project, the kinetic and thermodynamic factors that control layer formation will be explored in terms of specific chemical and physical features of the tethering reaction. These include polymer molecular weight, polymer architecture, and end group-surface interaction. For this, model polymers that provide a wide variation of polymer architecture, molecular weight, and tethering entity will be synthesized by living anionic polymerization. Other quantities that will serve as independent variables are temperature, concentration, solvent (and there interaction between polymer backbone segments and solvent), chemistry of the reactive sites on the solid surface (and thereby interaction between reactive sites and end-functional groups of the polymer chains), and energetics of the solid surface. The tethering reactions of the model polymers to solid surfaces under different conditions will be monitored by means of a recently developed, real-time method based on size-exclusion chromatography.The data obtained from the above studies and the principles that emerge will lead to a comprehensive description of the kinetics of tethering and an evaluation of the thermodynamic factors that influence the process. From this, we will develop of a set of logical guidelines and a general applicable mathematical model of tethering kinetics that can be used for empirical control manipulation of tethered layer structure.