Using Long‐Chain Polymechanophores to Explore the Differences in Mechanoactivation During Nozzle Flow and Ultrasonication

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Abstract
Polymer mechanochemistry harnesses mechanical strain to control chemical reactivity. Here, we study an ultrahigh molecular weight polymechanophore system, poly(BCH‐Naph). We first activate the polymechanophore through the standard and accepted method of ultrasonication, which relies on many localized flows driven by cavitation. Second, we compare these results with activation during flow through nozzles, where the flow conditions can be fully characterised and are a step toward real production processes. We find that each method of activation has its own unique distribution of strain and strain rate, demonstrating that we cannot rely on standard ultrasonication testing when considering flow‐based applications as the results are not correlated quantitatively. It is a common observation that below a limiting chain length, there is insufficient force generated to activate mechanophores. Here, using the ultrahigh molecular weight system, we found fragments of much smaller molecular weights than previously achieved under single‐pass flow conditions. We can see that the already‐elongated polymer can undergo multiple scission events when it is trapped within a high shear flow region. This research on the mechanoactivation of polymechanophore solutions in nozzle flow is an important step toward the informed design of mechanophore‐containing systems programmed to activate during specific, industrially‐relevant fluid flows.
Funding Information
  • Army Research Office (W911NF‐15‐1‐0525)
  • National Science Foundation (2350170)
  • Engineering and Physical Sciences Research Council (EP/S009000/1)

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