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Chemistry
Chemistry Defense: Jafer Vakil: Structure-Activity Relationships in Reactive Strand Extension Mechanophores
Wednesday, November 12,
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Speaker(s): Jafer Vakil
Structure-Activity Relationships in Reactive Strand Extension Mechanophores
Quantitative relationships between molecular behavior on the level of a single polymer strand and the physical behavior of a polymer network are severely lacking. Identifying such relationships would enable molecular level control of macromaterials and provide the theoretical scaffold for designing materials with diverse properties and functionalities. Mechanochemistry has realized reactive strand extension (RSE) as a mechanically coupled chemical reaction that works to release stored length and toughen polymer networks. The consequence of RSE in various forms is discussed - the installation of stored length into backbone strands, the consequence of topological RSE, and the potential for unlimited RSE via the mechanochemistry of azetidine. A modular approach is described to first characterize polymer precursors before they are placed into networks, and the resultant improvements toughness are reported. We report fourfold improvements to the tearing energy of acrylic elastomers installed with a bis(trimethylsilyl)-containing ferrocene which breaks at lower forces than traditional ferrocene, afforded by a novel, agnostic-like interaction which stabilizes the transition state during Fe-Cp dissociation. The mechanochemistry of azetidine is also described.
Quantitative relationships between molecular behavior on the level of a single polymer strand and the physical behavior of a polymer network are severely lacking. Identifying such relationships would enable molecular level control of macromaterials and provide the theoretical scaffold for designing materials with diverse properties and functionalities. Mechanochemistry has realized reactive strand extension (RSE) as a mechanically coupled chemical reaction that works to release stored length and toughen polymer networks. The consequence of RSE in various forms is discussed - the installation of stored length into backbone strands, the consequence of topological RSE, and the potential for unlimited RSE via the mechanochemistry of azetidine. A modular approach is described to first characterize polymer precursors before they are placed into networks, and the resultant improvements toughness are reported. We report fourfold improvements to the tearing energy of acrylic elastomers installed with a bis(trimethylsilyl)-containing ferrocene which breaks at lower forces than traditional ferrocene, afforded by a novel, agnostic-like interaction which stabilizes the transition state during Fe-Cp dissociation. The mechanochemistry of azetidine is also described.
