Mechanistic Studies of Atom Transfer Radical Addition and Polymerization

卡内基梅隆大学化学系Krzystof Matyjaszewski教授得到了有机和高分子化学计划的支持，用于原子转移自由基聚合的研究，该计划基于自由基聚合将单体转化为聚合物。这项研究的目的是确定ATRA和ATRP中催化物种和中间物种的结构，并建立反应的烷基、卤化物、金属和配体组分的结构-反应性关联。这些目标将通过采用一系列化学分析技术以及对模型化合物反应的动力学和产物进行检查来实现。更具体地说，将使用EXAFS、EPR、UV-VISE和其他光谱方法确定各种金属/配体络合物在非极性介质中的结构。这是必需的，因为关于非极性介质(如乙烯基单体)中此类络合物的结构的信息非常少。另一个重点领域是测定卤代烃/金属催化剂对的活化和失活速率常数。ATRA和ATRP生产控制良好的产品的能力在很大程度上取决于这些动力学参数，因此它们的测定对于开发新的更高效的催化剂至关重要。对ATRA和ATRP中涉及的物种的结构和反应活性的系统研究将有助于更深入地了解这些反应。这反过来将促进和优化这两种合成方法，例如开发更有效的催化剂，以便能够更高效地生产新材料(包括小型有机化合物和聚合物)，并具有更高的产率和选择性。卡内基梅隆大学化学系的Krzystof Matyjaszewski教授使用原子转移自由基聚合(ATRP)已经能够聚合各种单体，包括各种苯乙烯、丙烯酸酯和甲基丙烯酸酯以及其他单体如丙烯腈、乙烯基吡啶和二烯。虽然所描述的许多聚合物类型都是使用其他活性聚合制备的，但ATRP仍然是最强大、用途最广、简单和廉价的。近40年来，研究人员一直在努力开发一种活性自由基聚合。寻找替代方案是因为其他类型的活性聚合受到许多因素的严重限制：只能使用少量单体，反应对水分敏感，两个或两个以上单体不能随机共聚。相比之下，自由基聚合可以聚合数百种单体，可以共聚两个或更多个单体，可以在水中以乳液或悬浮液的形式进行。Matyjaszewski研究小组是第一个开发出使用简单、廉价聚合系统的“受控/活性自由基聚合”(CRP)的研究小组。它能够聚合各种单体，对微量杂质(水、氧和阻聚剂)具有耐受性，很容易应用于工业过程。开发的体系被称为原子转移自由基聚合(ATRP)。ATRP是一个强大的体系，引起了工业界和学术界聚合物化学家的极大兴趣。行业杂志《科学观察》最近将三篇ATRP论文列入了今日化学被引用论文的前十名。几家商业公司正在寻求CRP，195项专利申请证明了这一点，仅ATRP就有72项专利申请。与这种方法相关的第一个商业产品将于今年上市。最初的应用与涂料有关，但与分散剂、粘合剂、添加剂、润滑剂和化妆品相关的应用将很快跟进。

Professor Krzystof Matyjaszewski of the Department of Chemistry at Carnegie Mellon University is supported by the Organic and Macromolecular Chemistry Program for research on atom transfer radical polymerization, which is based on the use of radical polymerization to convert monomer to polymer. The purpose of the proposed research is to determine the structure of the catalytic and intermediate species in both ATRA and ATRP, and to build structure-reactivity correlations for alkyl, halide, metal and ligand components of the reactions. These objectives will be met by employing an array of chemical analysis techniques as well as examination of the kinetics and products of the model compound reactions. More specifically, the structures of the catalyst in non-polar media will be determined for various metal/ligand complexes using EXAFS, EPR, UV-Visible and other spectroscopic methods. This is required because very little information regarding the structures of such complexes in non-polar media (such as vinyl monomers) exists. Another area of focus is the determination of activation and deactivation rate constants of alkyl halide/metal catalyst pairs. The ability of ATRA and ATRP to produce well-controlled products depends heavily on these kinetic parameters, and therefore their determination is of vital importance in the development of new and more efficient catalysts. The systematic investigation of the structures and reactivities of the species involved in ATRA and ATRP will lead to a greater depth of understanding of these reactions. This will, in turn, advance and optimize both synthetic methods, such as the development of more effective catalysts, so that new materials (including small organic compounds and polymers) can be produced more efficiently and with greater yields and selectivity.Professor Krzystof Matyjaszewski of the Department of Chemistry at Carnegie Mellon University using atom transfer radical polymerization (ATRP) has been able to polymerize a wide range of monomers including various styrenes, acrylates and methacrylates as well as other monomers such as acrylonitrile, vinyl pyridine, and dienes. Although many of the polymer types described have been prepared using other living polymerizations, ATRP remains the most powerful, versatile, simple, and inexpensive. Researchers have been striving to develop a living radical polymerization for nearly 40 years. An alternative was sought because other types of living polymerizations are severely limited by many factors: only a small number of monomers can be used, the reactions are sensitive to moisture, and two or more monomers cannot be randomly copolymerized. Radical polymerization, in contrast, can polymerize hundreds of monomers, can copolymerize two or more monomers, and can be performed in water as emulsions or suspensions. The Matyjaszewski research group was the first to develop a "controlled/living radical polymerization" (CRP) that used a simple, inexpensive polymerization system. It is capable of polymerizing a wide variety of monomers, is tolerant of trace impurities (water, oxygen, and inhibitor), and is readily applicable to industrial processes. The system that was developed was termed Atom Transfer Radical Polymerization (ATRP). ATRP is a robust system that has generated much interest among polymer chemists in both industry and academia. Science Watch, a trade journal, has recently listed three ATRP papers among the top ten cited papers in chemistry today. Several commercial companies are pursuing CRP as evidenced by 195 patent applications with 72 related to ATRP alone. The first commercial product related to this method will be available this year. The first applications are related to coatings but applications related to dispersants, adhesives, additives, lubricants, and cosmetics will quickly follow.