Supramolecularly Templated Living REP-ROP Polymerizations and Block Copolymers

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Celtic art, Boy Scout knots, Mobius strip rings, and M.C. Escher's art have fascinated the viewer and challenged their ability to trace the origin of connectivity. For some time now, mathematicians have described the topology of rings and cyclic overlapping structures with their programmable qualities into the so-called Knot Theory. In polymer science, understanding how long polymer chains become tangled and how to get those tangled chains to dissolve in a solution can result in new materials with interesting physical properties and chemical properties that can extend the applications of plastics, coatings, rubber, and composites. There are many opportunities for training and mentoring future scientists in this interdisciplinary and practical field. This research helps preparing a workforce that solves complex problems and produces valuable products. This project focuses on the design and synthesis of new catenated polymer and block copolymer compositions via monomer ring opening (RO) and macroinitiator ring expansion polymerizations (REP) or REP-ROP Polymerizations. By utilizing the Knot Theory, it may be possible to obtain various knotted macromolecules, which have controlled entanglements as well as block copolymer composition with high yields and high molecular weight. The approaches towards the synthesis of catenated macromolecules involve: 1) phenanthroline-based macroinitiator templates; 2) homopolymers and block copolymers derived from atom transfer radical polymerization methods and ring closures with atom transfer radical coupling; 3) ring expansion strategies with polycaprolactones; and 4) polymer reactions that modify the side groups and control the composition and interaction parameters of the chains. Characterization methods include nuclear magnetic resonance spectroscopy, MALDI mass sppectrometry, atomic force microscopy, size-exclusion chromatography, and rheometry, which verify the polymer's chemical structure, topology, and phase separation in solution and solid state. Collaborations with polymer physicists, theorists, and rheologists are pursued to harness the properties of the catenated polymers as materials and compatibilizers for practical applications.