Tuning Polymerization-Induced Self-Assembly in Epoxy Thermosets for Improved Static and Dynamic Properties

Polymer thermosets are frequently modified via polymerization-induced self-assembly, wherein the addition of secondary or higher order components that organize 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 self-assembly in epoxy thermosets 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. Consequently, the glass transitions, modulus profiles, coefficients of thermal expansion, and curing- and thermal-induced residual stresses are profoundly impacted by seemingly subtle changes in the epoxy formulation. This presentation will also cover the dynamic response of these materials under high deformation rates. Of particular note, we have observed anomalous shockwave propagation characteristics in specific microstructures that differ significantly from the response of conventional, homogeneous epoxies. This work offers the opportunity to design epoxy thermosets with increased performance based on an improved understanding of the relationships between self-assembly behavior and the physical properties manifested.