Synergistic Enhancement of Damping Properties of <scp>PU</scp> / <scp>EP</scp> System Achieving Through Synchronous Incorporation of Long Aliphatic Chain Tailed Benzene Dangling Moiety and Bisphenol A Main Chain

ABSTRACT Traditional polyurethane elastomers usually exhibit a narrow damping temperature range, which restricts their use in wide‐temperature environments. In this work, a molecular design strategy based on synergistic regulation is proposed: by simultaneously introducing a “short‐rigid–long‐flexible” dangling hybrid segment and a non‐freezing aromatic main chain into a polyurethane/epoxy interpenetrating polymer network (PU/EP IPN), the diversity of molecular chain dynamics and the intermolecular friction are effectively enhanced, thereby broadening the damping temperature range and increasing the loss factor. Using structurally tailored dangling moieties to construct the PU/EP IPN, dynamic mechanical analysis (DMA), broadband dielectric spectroscopy (BDS), and atomic force microscopy (AFM) were systematically employed to elucidate the molecular motions and microphase separation behavior. The results demonstrate that the cooperative action of the “short‐rigid–long‐flexible” dangling hybrid segment and the non‐freezing bisphenol A unit significantly enriches molecular motion and strengthens intermolecular friction. Consequently, the effective damping temperature range is markedly broadened (Δ T = 112.8°C) and the maximum loss factor is substantially improved (tan δ = 1.02). This work provides a feasible and generalizable pathway for designing high‐performance damping elastomers with broad service temperature range based on PU/EP IPN architectures.