Contribution of Hard Domains to Energy Dissipation in Polyurea and Polyurethane-Based Segmented Elastomers

Segmented elastomers, such as polyurea, dissipate energy through various mechanisms. Although dynamic stiffening of soft domains is often cited, growing evidence highlights the dominant role of hydrogen-bond breaking and reformation. To clarify the specific role of hard domains, we synthesized polyurea, polyurethane, and polyurethane-urea with systematically varied hard-domain order, while maintaining comparable soft-domain dynamics at a target strain rate. Microballistic impact experiments revealed two distinct dissipation regimes, with ordered polyurea performing best. FTIR spectroscopy and strain-rate-dependent cyclic tension experiments confirmed an order–disorder transition coinciding with maximum energy dissipation. These findings emphasize the role of ordered hard domains in elastomer design.