Tuning Polymerization-Induced Self-Assembly in Polymer Thermosets to Optimize Their Physical Properties

Polymer thermosets are frequently modified via polymerization-induced self-assembly (PISA), wherein the addition of secondary or higher order components that phase separate during the polymerization is intended to improve a specific property. Generally speaking, it is challenging to control the characteristic self-assembled length scale in such materials beyond a limited range. This presentation will describe an approach to PISA in step-growth polymer networks that enables the length scale to be tuned over a broad range, from nanoscale to macroscale. The key element of this approach is a balance of multiple reactive species that simultaneously favor and disfavor phase separation. We demonstrate how ensuing, systematic variation of the length scale leads to exquisite control over the curing behavior and glass transition of the resultant materials. We further discuss application of this approach in the optimization of physical properties, including for rubber-modified epoxies where toughness is critically impacted by rubber particle size, as well as for the development of materials with improved damping performance. Our results and insights may help guide the future design of polymer thermosets with precisely tailored microstructures and unique combinations of physical properties.