This award by the Inorganic, Bioinorganic, and Organometallic Chemistry Program to Professor Bradford B. Wayland of Temple University focuses on the development of organo-metal mediated living radical polymerization (LRP), the preparation of new classes of homo and block copolymer materials, and the self assembly of block copolymers into nanostructured materials. Organo-cobalt porphyrin complexes mediate the highly precise LRP of monomers to form low polydispersity homo-polymers and block copolymers. The self-assembly of block copolymers in both solution and the solid state is utilized in forming nanoscale, structured materials with uses in electronics, photonics, and drug delivery. These applications have the potential to impact the economy, the environment, and society. Graduate and undergraduate students participate in the research and their experiences vary from the fundamental design and synthesis of catalysts and polymer materials to the evaluation of practical applications in collaboration with material scientists, engineers, and technologists.
Federal Award ID: 0809395 This program in transition metal catalysis and polymer materials spans a set of related objectives to explore and utilize the reactivity of metal-centered radical species and organometallic derivatives in the control of radical polymerization by catalytic chain transfer (CCT) and living radical polymerization (LRP). Low spin cobalt(II) metal-centered radicals are highly effective in catalytic chain transfer for radical polymerization which controls the molecular weight and introduces end group alkene functionality. Organo-cobalt porphyrin complexes have recently been observed to mediate a highly precise living radical polymerization of acrylate monomers to form low polydispersity homo-polymers and block copolymers. This new approach to obtain LRP occurs by a degenerative transfer pathway that involves rapid interchange of polymeric radicals in solution with polymeric organic units in organo-cobalt porphyrin complexes ((por)Co-P*). This pathway to obtain living radical polymerization is a transition metal form of degenerative transfer that we refer to as radical interchange polymerization (RIP). Substantially larger rates of polymerization, much wider range of applicable monomers and simplified metal catalyst materials are several important advantages for the radical interchange process compared to stable free radical polymerization (SFRP) mediated by metal-centered radicals. The scope of applications in polymer synthesis is broadened by compatibility of both the radical polymerization process and the metallo-porphyrin catalyst materials with a wide range of media including water. The novelty and fundamental significance of the radical interchange process and the potential technological importance in forming new classes of functionalized polymers has dictated that this program become focused on radical interchange processes. While the broad objectives of metalloradical reactivity including chain transfer catalysis were advanced , the majority of the studies were focused on exploring the radical interchange process for organo-cobalt porphyrin complexes, evaluating a wide range of organo-metal species for radical interchange polymerization , and exploiting the RIP LRP method in the preparation of new classes of functionalized polymeric materials. Appropriately tailored segmented polymers containing blocks that differ significantly , self-assemble in solution and in the solid state into micelles and nano-structured arrays that haveapplications in electronics, photonics, membranes, drug delivery and other medical applications. Development of selective polymer membrane for uses in gas separations and water purification have environmental, societal, political and economic impact . A core function and objective of academic research is to educate and train scientists and technologists to address the next generation of technological and societal issues . Members of the research group involved in block copolymers are exposed to the major technological and environmental issues where applications of polymeric materials have the potential for substantial impact . The fundamental design and synthesis aspects of the program are integrated with structure and property evaluations that are carried out in close collaboration with engineering groups . The researches are thus directly involved in a breadth of research experiences that extend substantially beyond the borders of the conventional disciplines . This approach is resulting in producing researchers prepared to address issues with a multidisciplinary perspective .
