CAREER: Iron Polymerization Catalysis for the Synthesis of High Performance Degradable Polymers

在这个由化学系化学催化计划资助的项目中，波士顿学院的Jeffery A.Byers教授正在开发方法，将由可再生原料(如玉米和大豆油)制成的化学品转化为具有多种性能的可生物降解塑料。这些方法是基于使用催化剂来完成化学转化，而正在开发的特殊催化剂是基于低毒、富含稀土的元素铁。这种催化剂能够制造具有新结构和新组成的塑料，预计这些塑料将显示出更好的物理性能。为了提高对新的、可持续材料的需要的认识，并促进未被充分代表的少数群体参与STEM领域，拜尔斯教授正在开发、测试和传播一套经验演示，向K-9学生教授科学方法以及催化和聚合物。拜尔斯教授还为高中生举办了一次“从纸到塑料”的研讨会，以探索如何制备可持续发展的材料。在这个项目中，拜尔斯教授正在研究双(亚氨基)吡啶-双醇盐铁络合物作为D，L-丙交酯和环氧化物聚合的催化剂。在+2氧化态，络合物催化D，L-丙交酯聚合，但不催化环氧化物聚合；在+3氧化态，络合物催化环氧化物聚合，但不催化D，L-丙交酯聚合。因此，人们正在探索氧化还原化学或电化学来在两种不同的反应模式之间切换催化剂，这种催化剂的这一特性正被用于合成环氧化物和丙交酯之间的多嵌段共聚物，以及开发氧化还原触发的交联反应。正在探索的终止化学将连接每个金属中心上两个不断增长的聚合物链。这些聚合物结构修饰有望产生具有与目前使用的生物降解聚合物相比独特的性能的生物降解聚合物。该项目的更广泛影响涉及氧化还原转换在催化中调节正交反应的潜在用途、可持续材料的有用性以及计划的教育活动。

In this project funded by the Chemical Catalysis program of the Chemistry Division, Professor Jeffery A. Byers of Boston College is developing methods to convert chemicals made from renewable feedstocks, such as corn and soybean oil, into biodegradable plastics with a wide range of properties. These methods are based upon using catalysts to accomplish chemical conversions, and the particular catalysts being developed are based upon a low toxicity, earth abundant element, iron. The catalysts are able to make plastics with new structures and compositions that are expected to display improved physical properties. To increase awareness of the need for new, sustainable materials and to promote the participation of under represented minorities in STEM fields, Professor Byers is developing, testing and disseminating a set of experiential demonstrations for teaching K-9 students about the scientific method as well as catalysis and polymers. Professor Byers is also working on a "Paper to Plastics" workshop experience for high school students to discover how sustainable materials can be prepared.In this project, Professor Byers is studying bis(imino)pyridine-bisalkoxide complexes of iron as catalysts for the polymerization of D,L-lactide and epoxides. While in the +2 oxidation state the complexes catalyze the polymerization D,L-lactide but not epoxides and in the +3 oxidation state the complexes catalyze the polymerization of epoxides but not D,L-lactide. Thus, redox chemistry or electrochemistry is being explored to switch the catalyst between two different modes of reactivity, and this property of the catalyst is being exploited for the synthesis of multiblock copolymers between epoxides and lactide as well as the development of a redox-triggered crosslinking reaction. Termination chemistry is being explored that will link the two growing polymer chains on each metal center. These polymer structure modifications are expected to result in biodegradable polymers with properties that are unique compared to currently used biodegradable polymers. The broader impacts of the project pertain to the potential uses of redox switching to mediate orthogonal reactivity in catalysis, the usefulness of sustainable materials, and the planned educational activities.