Stochastic Bullvalene Architecture Modulates Structural Rigidity in π‐Rich Macromolecules

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 mo...

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Bibliographic Details
Published in:Angewandte Chemie International Edition 2023-05, Vol.62 (19), p.e202301695-n/a
Main Authors: Pomfret, Meredith N., Sun, Peiguan B., Huang, Zheng, Freund, Anna C., Miyoshi, Toshikazu, Golder, Matthew R.
Format: Article
Language:English
Subjects:
Chemical synthesis
Conformation
Crystallization
Fluxional Molecule
Hydrocarbon
Isomers
Macromolecules
NMR
Nuclear magnetic resonance
Pericyclic
Pi-Material
Polymer
Polymers
Rigidity
Stiffness
Stochasticity
Textiles
Thermal properties
Thermodynamic properties
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Summary: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. Bullvalene, a shape‐shifting molecular cage, is incorporated into a pi‐rich polymer backbone to modulate chain architecture. Stochastic bullvalene isomers within the backbone lead to a kinked chain architecture and decreased thermal transitions that are tunable based on percent bullvalene incorporation.
ISSN:1433-7851
1521-3773
DOI:10.1002/anie.202301695