Metal-Centered Radicals and Organometallic Complexes in Controlled Radical Polymerizations of Olefins

布拉德福德医生B。韦兰，化学系，宾夕法尼亚大学，是由化学系的无机，生物无机和有机化学计划的支持，用于研究金属中心的自由基和有机金属络合物在烯烃的受控自由基聚合。低自旋钴（II）金属中心自由基在自由基聚合期间控制分子量并引入端基烯烃官能度的催化链转移中是高度有效的。因此，动力学-机械研究的催化链转移低自旋钴（II）金属自由基和测量的有机钴和其他有机金属键离解热力学将进行。有机钴卟啉配合物介导丙烯酸酯单体的高度精确的活性自由基聚合，以形成低多分散性的均聚物和嵌段共聚物。因此，将研究该聚合过程的机理，将评估催化聚合的有机金属物种的范围，并确定在聚合过程中促进和抑制自由基交换的因素。活性自由基聚合是制备新型功能化高分子材料的重要方法，聚烯烃是重要的工业产品。这项研究将开发一种合理的方法来合成各种聚烯烃，并可能导致新的结构定义的嵌段共聚物与未开发的材料性能。参与这项研究的学生不仅将学习涉及无机和有机化学的复杂方法，还将了解能源相关研究，聚合物化学，催化和材料科学的主要问题和挑战。

Dr. Bradford B. Wayland, Chemistry Department, University of Pennsylvania, is supported by the Inorganic, Bioinorganic, and Organometallic Chemistry Program of the Chemistry Division for the study of metal-centered radicals and organometallic complexes in the controlled radical polymerizations of olefins. Low spin cobalt(II) metal-centered radicals are highly effective in the catalytic chain transfer that controls molecular weight and introduces end group alkene functionality during radical polymerization. Consequently, kinetic-mechanistic studies of catalytic chain transfer by low spin cobalt(II) metalloradicals and the measurement of organo-cobalt and other organo-metal bond dissociation thermodynamics will be undertaken. Organo-cobalt porphyrin complexes mediate a highly precise living radical polymerization of acrylate monomers to form low polydispersity homo-polymers and block copolymers. Hence, the mechanism of this polymerization process will be studied, the scope of organo-metallic species that catalyze the polymerization will be evaluated, and the factors that promote and inhibit radical interchange during the polymerization will be determined. The living radical polymerization method will be exploited to prepare new classes of functionalized polymeric materials.Polyolefins are important commercial products. This research will develop a rational approach to the synthesis of various polyolefins and potentially result in new structurally defined block copolymers with unexplored material properties. Students involved in the study will learn not only sophisticated methods involving inorganic and organic chemistry, but will be introduced to major issues and challenges in energy-related research, polymer chemistry, catalysis and materials science.