Alicia Castagna

Phase Separated Microstructure and Structure–Property Relationships of High Strain Rate Elastomeric Polyureas

The family of polyurea elastomers is of keen interest for the mitigation of blast and shock energy, particularly for protection against ballistic impact and traumatic brain injury. Polyureas are alternating copolymers, yet strong bidentate hydrogen bonding leads to nanoscale segregation of urea-containing “hard” segments. Compared with chemically similar polyurethane segmented copolymers, relatively little is known about the fundamental nanostructure (property) or thermal history relationships of polyureas. An overview of some of our work in this area is presented in this chapter. This includes the experimental investigation of the nanoscale morphology of common polyureas using a variety of experimental probes (including X-ray scattering), along with companion coarse-grained molecular level computational simulations of the nanoscale segregation and the unlike segment demixing process. Insights into polyurea molecular dynamics are also developed using broadband dielectric spectroscopy and dynamic mechanical analysis.