Stochastic Bullvalene Architecture Modulates Structural Rigidity in π-Rich Macromolecules |
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Authors: | Meredith N Pomfret Peiguan B Sun Zheng Huang Anna C Freund Prof?Dr Toshikazu Miyoshi Prof?Dr Matthew R Golder |
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Institution: | 1. Department of Chemistry and Molecular Engineering & Science Institute, University of Washington, 36 Bagley Hall, Seattle, WA 98195 USA;2. School of Polymer Science and Polymer Engineering, The University of Akron, Akron, OH 44325 USA |
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Abstract: | The synthesis and processing of π-rich polymers found in novel electronics and textiles is difficult because chain stiffness leads to low solubility and high thermal transitions. The incorporation of “shape-shifting” molecular cages into π-rich backbone provides an ensemble of structural kinks to modulate chain architecture via a self-contained library of valence isomers. In this work, we report the synthesis and characterization of (bullvalene-co-phenylene)s that feature smaller persistence lengths than a prototypical rigid rod polymer, poly(p-phenylene). By varying the amount of bullvalene incorporation within a poly(p-phenylene) chain (0–50 %), we can tune thermal properties and solution-state conformation. These features are caused by stochastic bullvalene isomers within the polymer backbone that result in kinked architectures. Synthetically, bullvalene incorporation offers a facile method to decrease structural rigidity within π-rich materials without concomitant crystallization. VT NMR experiments confirm that these materials remain dynamic in solution, offering the opportunity for future stimuli-responsive applications. |
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Keywords: | Fluxional Molecule Hydrocarbon Pericyclic Pi-Material Polymer |
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