Synthesis and molecular dynamics study of high-damping polyurethane elastomers based on the synergistic effect of dangling chains and dynamic bonds

Damping elastomers are widely used to control vibration and noise in various fields. However, there are common issues of weak damping temperature range controllability and poor mechanical properties as well as insufficiently tailored molecular structures in high-damping elastomers. Therefore, we have introduced poly(ethylene glycol) monomethyl ether (MPEG) dangling chains and dynamic disulfide bonds to synthesize polyurethane elastomers with an effective damping (tan δ ≥ 0.3) temperature range of 143 °C (−43–100 °C) and a high mechanical strength of 11.43 ± 0.51 MPa. To further probe the effect of dangling chains and dynamic disulfide bonds on the multi-scale molecular structure and properties of PU damping material, the molecular dynamics and dynamic mechanics were analyzed by combining dynamic mechanical analysis (DMA) and broadband dielectric relaxation spectroscopy (BDRS). The Maxwell–Wagner–Sillars (MWS) interfacial polarization process was observed in a PU elastomer after introducing the dangling chains, indicating a lower degree of microphase separation and faster segmental motion to improve the damping properties. After introducing disulfides, the dynamic exchange of disulfides is helpful for segmental motion to increase molecular chain friction and mechanical energy consumption. The relationship among the multi-scale chain structure, phase morphology and damping properties was revealed, thus providing a theoretical basis and technical reference in the development of novel high-damping materials.