An Integrated Theoretical and Experimental Study of a Free Radical Polymerization and Polymer Reaction Kinetics

提出了一个实验与理论相结合的方案，其目标是在自由基聚合(FRP)和聚合物反应动力学这两个紧密耦合的领域取得根本进展。物理和化学在这些现象中扮演着同样重要的角色。相应地，该程序联合和协调了在反应聚合物系统方面具有丰富经验的实验光化学家(NJT)和理论聚合物物理学家(BOS)的努力。在前一资助期间已完成的研究中，实验。理论、化学和物理一直密不可分。玻璃钢中的复杂过程涉及聚合物科学和自由基化学的许多基本方面。一个关键的作用是由带有自由基端基的不断增长的聚合物之间的反应所发挥的，这些末端基团被称为“活性链”或“大分子药物”。正因为如此，玻璃钢与聚合物反应动力学的一般领域是紧密交织在一起的。由于玻璃钢中的活性链条寿命短，其分子量分布(MWD)从未被测量过。在前一次供资期间，首次开发了一种测量玻璃钢活MWD的方法。激光光解被用来将瞬变的生物种群“复制”成荧光标记的死链种群，这可以用标准方法进行分析。在拟议的研究中，线性玻璃钢的活MWD将被影印在预先准备的已知长度和浓度的死链背景中。复印和其他光谱测量将对稳态玻璃钢和从闪光光解产生的高度新颖的初始条件演变而来的非稳态玻璃钢进行测量。理论将尝试预测这些实验的结果，扩展了在第一个资助期开发的处理非常稀薄的死人背景的理论。这些实验能够以某种方式直接检查尚未解决的根本问题，这是直到现在才可能做到的。例如，分别在纠缠和非纠缠死矩阵中进行影印，将提供对纠缠在FRP中的作用和著名凝胶效应的性质的独特检查。第二类项目将涉及聚合物反应动力学的基本原理。如果成功，这些测量将对反应聚合物系统和整个聚合物物理领域产生重大影响，因为几乎所有关于k和k(T)的理论预测都从未得到验证。有了这个奖项，有机和高分子化学计划将支持哥伦比亚大学化学系的Nicholas J.Turro和Ben O‘Shaughnessy教授的研究。这项研究是独特的，因为它提供了一个机会，应用理论和实验努力，以了解自由基聚合的机制。玻璃钢在聚合物工业中具有巨大的技术重要性，用于合成大量的聚合物材料。实验光化学家的专业知识将与理论聚合物物理学家的专业知识相结合，以提供一个跨学科的环境，参与其中的学生将在这两个方面的研究中接受培训。

An integrated program of experiment and theory is proposed whose objective is fundamental progress in the closely coupled fields of Free Radical Polymerization (FRP) and Polymer Reactions Kinetics. Physics and chemistry play equally central roles in these phenomena. Correspondingly, the program unites and coordinates the efforts of an experimental photochemist (NJT) and a theoretical polymer physicist (BOS) with extensive experience in reacting polymer systems. In the accomplished research during the previous funding period, experiment. theory, chemistry and physics have been inseparable. The complex processes in FRP involve many fundamental aspects of polymer science and radical chemistry. A crucial role is played by reactions between growing polymers carrying radical end groups, known as "living chains" or "macroradicals." For this reason, FRP and the general field of polymer reaction kinetics are deeply intertwined.Since the living chains in a FRP have short lifetimes, their molecular weight distributions (MWD) have never been measured. In the previous funding period a method was developed to measure FRP living MWDs for the first time. Laser photolysis is used to "photocopy" the transient living population into a fluorescence-labeled dead chain population, which can be analyzed by standard methods. In the proposed research, living MWDs of linear FRP will be photocopied in pre-prepared dead chain backgrounds of known length and concentration. Photocopies and other spectroscopic measurements will be made of steady state FRP, and of non-steady state FRPs evolving from highly novel initial conditions created by flash photolysis. Theory will attempt to predict the outcome of these experiments, extending the theory developed in the first funding period dealing with very dilute dead backgrounds. The experiments enable direct examination of fundamental unresolved issues in a way, which has not been possible until now. For example, photocopying in entangled and unentangled dead matrices, respectively, will provide a unique examination of the role of entanglements in FRP and the nature of the celebrated gel effect. A second family of projects will address fundamentals of polymer reaction kinetics. If successful, these measurements will have significant impact on the field of reacting polymer systems and polymer physics in general since virtually all theoretical predictions on k and k(t) have never been tested.With this award the Organic and Macromolecular Chemistry Program is supporting the research of Professors Nicholas J. Turro and Ben O'Shaughnessy of the Department of Chemistry at Columbia University. This research is unique in that it provides an opportunity to apply theoretical and experimental efforts to understanding the mechanism of free radical polymerizations. FRP is of enormous technological importance in the polymer industry, used to synthesize a great number of polymeric materials. The expertise of an experimental photochemist will combine with that of a theoretical polymer physicist to provide an interdisciplinary environment where the students involved will be trained in both aspects of the research.