Going with the Flow: Tunable Flow‐Induced Polymer Mechanochemistry

Abstract

Mechanical forces can drive chemical transformations in polymers, directing reactions along otherwise inaccessible pathways, providing exciting possibilities for developing smart, responsive materials. The state‐of‐the‐art test for solution‐based polymer mechanochemistry development is ultrasonication. However, this does not accurately model the forces that will be applied during device fabrication using processes such as 3D printing or spray coating. Here, a step is taken toward predictably translating mechanochemistry from molecular design to manufacturing by demonstrating a highly controlled nozzle flow setup in which the shear forces being delivered are precisely tuned. The results show that solvent viscosity, fluid strain rate, and the nature of the breaking bond can be individually studied. Importantly, it is shown that the influence of each is different to that suggested by ultrasonication (altered quantity of chain breakage and critical polymer chain length). Significant development is presented in the understanding of polymer bond breakage during manufacturing flows to help guide design of active components that trigger on demand. Using an anthracene‐based mechanophore, the triggering of a fluorescence turn‐on is demonstrated through careful selection of the flow parameters. This work opens the avenue for programmed chemical transformations during inline manufacturing processes leading to tunable, heterogeneous final products from a single source material.

Organic neuromorphic devices: Past, present, and future challenges

“…65 When printing functional macromolecules, it is important to understand the forces they experience as they flow through pipes, pumps, and ancillary equipment, and that the shear, extensional, or thermal forces are not having a deleterious effect, 66 as is also the case for flow through printheads and nozzles. 67,68 Once out of the nozzle, there are complex interdependencies between the formulation and printing actuation that determine if stable, repeatable drop or filament formation is feasible. This is often a key point that then requires additional formulation modification with the addition of viscosity and surface tension modifiers.…”

Introduction of a Luminophore into Generic Polymers via Mechanoradical Coupling with a Prefluorescent Reagent

“…[5] This method can be used for the preparation of block copolymers via growth from the cleaved macroradicals, and has great potential for applications of mechanoresponsive polymeric materials [5–7] . Despite this recent progress, the preparation of functional polymers via mechanoradical transformations has scarcely been reported [8] . In fact, introduction of a luminophore into generic polymers via mechanoradical coupling has not yet been explored (Figure 1 a).…”

“…[5][6][7] Despite this recent progress,t he preparation of functional polymers via mechanoradical transformations has scarcely been reported. [8] In fact, introduction of al uminophore into generic polymers via mechanoradical coupling has not yet been explored (Figure 1a). Such an ew approach would potentially allow the direct preparation of functional polymers from chemically stable generic polymers without sophisticated chemical synthesis.…”

Laminar flow-induced scission kinetics of polymers in dilute solutions

“…2011), or more broadly to activate force-sensitive compounds in the context of polymer mechanochemistry (May & Moore 2013; Willis-Fox et al. 2018, 2020).…”