"Getting Chemical Reactivity Into and Out of Polymer Networks"

Abstract.  Polymer networks typically fulfill a structural role, in which they bear an external load.  That load can be coupled to mechanically responsive functional groups – mechanophores – and used to accelerate and/or bias the outcome of a desired chemical reaction, including reactions that are impossible to achieve through other mechanisms.  The talk will begin with examples of this form of mechanochemistry in stoichiometric reactions as well as catalysis, including the fundamentals that underlie it. 

The remainder of the talk will focus on the use reactivity-guided molecular fracture pathways to rewrite traditional performance rules that dictate the limits of polymer network toughness and extensibility.  The approach is to embed mechanophores that behave like conventional components of polymer strands and junctions unless and until they are at or near a molecular site of pending fracture.  Depending on mechanophore placement and reactivity, polymer networks can be made an order of magnitude easier or an order of magnitude more difficult to tear.  Because improvements can be realized without any other measurable change in network properties and require changes to only a few percent of the overall material composition, mechanophores open possibilities for rapid upgrading of current best-in-class materials with minimal retroengineering.  

*This event is supported by, and is part of, the Aggarwal Lecture Series