Compatibility of high strength silica‐modified microcapsules modified with polydopamine in elastomer substrates

Abstract Microcapsules with polydopamine composite shell layer were successfully synthesized by functionalizing silica‐modified microcapsules containing isophorone diisocyanate. The components and micromorphology of silica‐modified microcapsules at different reaction periods were studied by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy. The structure of different microcapsules was characterized by FTIR, ¹H nuclear magnetic resonance and x‐ray photoelectron spectroscopy. The mechanical performances of different microcapsules were analyzed by nanoindentation technique. The compatibility and self‐healing efficiency of different microcapsules with the substrate were also investigated by the tensile tests. The results showed that the density of the silica‐modified microcapsule shell gradually increased and the mechanical performances were enhanced with the silica source. The hardness and elastic modulus of silica‐modified microcapsules in suitable core fraction (76.5 wt%) were 139.9 MPa and 2.2 GPa, which are 2.3 times and 4.8 times higher than those of untreated microcapsules, respectively. The functionalized modified microcapsules had excellent compatibility with the elastomeric substrate (PU‐PPG2000). At the same time, the self‐healing efficiency of the functionalized modified microcapsules in PU‐PPG2000 was 69.8%, which was 48.9% higher than that of the untreated microcapsules prepared under the same conditions. Silicon modification improved the density of microcapsules, enhancing their mechanical strength. At the same time, functionalization modification improved the interfacial bonding strength of microcapsules, further improving the compatibility with the polymer matrix. Highlights Microcapsules with different silicon sources are characterized. Microcapsules are functionalized with polydopamine. Individual microcapsules are tested for mechanical strength by nanoindentation. The compatibility of the functionalized microcapsules is excellent. The self‐healing efficiency of modified microcapsules is greater than 70%.