Interpenetrating Elastomers for High-Fidelity Shape Recovery and Broad Temperature Energy Dissipation.

The design of elastomers integrating high-fidelity shape memory behavior with broad-temperature energy dissipation remains a fundamental challenge due to the intrinsic trade-off between network rigidity and segmental mobility. Here, an interpenetrating polymer network (IPN) strategy is developed to fabricate polyurethane (PU)/brominated butyl rubber (BIIR) IPNs via a two-step process. The resulting IPN elastomers exhibit a sea-island morphology, with PU as dispersed rigid domains and BIIR as the continuous phase. Physical entanglements and internetwork confinement within the interpenetrated architecture contribute to effective shape memory behavior, resulting in shape fixity and recovery ratios of 94.0% and 90.2%, respectively, at 20 phr BIIR content. The large mismatch in glass transition temperatures and confined interfacial friction induces hierarchical segmental relaxation, leading to a broad damping temperature window (tanδ ≥ 0.3) of 154.8 °C. The IPNs further demonstrate repeatable energy dissipation over the tested cycles, a characteristic impact-force decay time of less than 0.1 s in the falling-ball test, and a 91% energy-loss fraction derived from the pendulum rebound test. The IPNs also exhibit effective acoustic insulation, reducing the transmitted acoustic amplitude to 20.6 mV. This work provides a general strategy for overcoming the trade-off between shape memory functionality and damping breadth, offering a platform for designing multifunctional elastomers for advanced flexible devices.