A larger number of studies successfully prepared various polymer materials with excellent self-healing properties, but the study on the underlying self-healing mechanism remains comparably backward and still unclear. In this study, we prepared a self-healing polyurethane-urea (PUU) elastomer based on noncovalent bonds. Then, a coarse-grained model of PUU was successfully constructed using the iteration Boltzmann inversion (IBI) method. Microphase separation and mechanical properties of PUU were reproduced using this model by coarse-grained molecular dynamics (MD) simulation. The three-stage healing mechanism comprised the following: (1) movement of the material to close the gap, (2) interdiffusion of the polymer, and (3) bond exchange. The mechanism was revealed by determining the effects of hard segment content on the microstructure (chain entanglement, interactions of soft and hard segments, chain motility) and healing capacity over healing time. In the initial stage of healing, the polymer chains were disentangled, and the degree of entanglement of the healed samples decreased. A novel experimental strategy confirmed the transition of hydrogen bonds from disorder to order during the healing process. The motility of the cut polymer chains (low molecular weight), especially the cut soft segment, and the disordered hydrogen bonds played a key role in the healing capacity. The increased content of the ordered hydrogen bonds led to the formation of a hard segment network, which was not conducive to healing. Finally, the promoting mechanism of external factors, such as heating and trace amount of solvent, on the healing of PUU was explained. Our work systematically and profoundly reveals the self-healing behavior and mechanism of microphase-separated PUU at the molecular level.

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Epoxidized solution‐polymerized styrene butadiene rubber (ESSBR) with different epoxidation degrees was prepared using formic acid as a catalyst. Experimental methods and density function theory calculation confirms that peroxyformic acid preferentially attacks trans‐1,4‐butadiene, and then cis‐1,4‐butadiene, and 1, 2‐butadiene is not epoxidated due to high energy barrier. Two SiO2/graphene oxide hybrids covalently linked with bis‐[3‐(triethoxysilyl)propyl]‐tetrasulfide or 3‐aminopropyltriethoxysilane (KH550) were prepared and named SiO2@TESPT@GO and SiO2@KH550@GO, respectively. The results for ESSBR composites filled by hybrid fillers indicate that the increase of epoxy degree can greatly improve the wet skid resistance while maintaining rolling resistance. Besides, in the case of the same epoxy degree, the rolling resistance of composites using hybrid fillers is lower than that of using SiO2 only. Notably, the SiO2@TESPT@GO/ESSBR composite with high epoxy degree (10.09%) has a good balance between wet skid resistance and low rolling resistance. Molecular dynamics simulation was further employed to perform fixed and cyclic stretching to give the mechanism for mechanical properties. Binding energy and mean square distance illustrate that that as the epoxy degree increases, on the one hand, the strong filler‐matrix interactions will make the movement of ESSBR chains keep up with the strain. On the other hand, the strong filler‐matrix and inter‐chain interactions provide more friction. These two factors lead to an increase in hysteresis loss. Besides, only moderate filler‐matrix interaction is conducive to the improvement of wet skid resistance, and too strong or too weak interaction is unfavorable.