Synergistic dual-crosslinking and multilevel hydrogen-bond engineering for high-damping polyurethanes

In advanced equipment and urban infrastructure, conventional damping materials fail to simultaneously deliver high energy dissipation, broad temperature-range responsiveness, and reliable mechanical performance. To address this challenge, we propose a molecular engineering strategy for polyurethane (PU) that constructs a dual-crosslinked network. This architecture synergistically integrates multilevel hydrogen-bonded physical interactions with chemical covalent crosslinks. Specifically, by using polycarbonate propylene glycol as the soft segment, we tailor the hydrogen-bonding interactions both within the hard segments and between the soft and hard segments. Simultaneously, we leverage the enhanced chain mobility and internal friction introduced by ether linkages and pendant methyl groups to achieve superior energy-dissipation capability. Furthermore, trimethylolpropane is introduced to provide additional covalent crosslinks, thereby enhancing thermal stability and mechanical robustness. We systematically elucidate how segmental architecture governs the microscopic hydrogen-bonding network, thermal transitions, and macroscopic mechanical and damping behaviors. Results show that increasing the hard segment content elevates the hydrogen-bonding index from 0.192 to 0.575, reflecting a pronounced reinforcement of the hydrogen-bonding network. Moreover, the synergistic physical-chemical dual-crosslink architecture imparts exceptional thermal stability (softening point: 272.7°C) and high tensile strength of 28.1 MPa. Thermal analysis, cyclic energy dissipation measurements, and dynamic mechanical analysis further verify that the PU maintains high energy dissipation efficiency across broad temperature and frequency ranges. The effective damping temperature range can be tuned from 3.2 to 74.3°C by adjusting the hard segment content. This work offers a new pathway for designing damping materials capable of operating under complex service environments.