Study on a novel flexible high dielectric poly (isoprene‐co‐acrylonitrile)/barium titanate composite with a reversible cross‐linked structure

Abstract Reversible cross‐linked structures are widely used to turn thermoset plastics into recyclable and self‐healing vitrimer materials, but seldom applied in traditional flexible rubber/ceramic composites. In this paper, dioxaborolanes based flexible poly (isoprene (IP)‐co‐acrylonitrile (AN)) vitrimer is synthesized as the rubber matrix by copolymerizing with functional monomers at 5°C for 7 h, and mixed with 5 wt% modified barium titanates (BT) to prepare flexible high dielectric vitrimer composite. The materials are characterized by FTIR, TGA, SEM, DMA, etc. The results indicate that reversible crosslinking can occur above 76.4°C, and copolymerizing with the dioxaborolanes based monomers can turn poly (IP‐co‐AN) into the flexible vitrimer. The poly (IP‐co‐AN)/BT vitrimer composite not only shows a good thermal stability below 145.6°C, but also exhibits an excellent particle dispersivity and a certain self‐healing function at 80°C. The poly (IP‐co‐AN)/BT vitrimer composite has a storage modulus E' about 3.18 MPa at 25°C and T _g about −5.4°C, and shows a higher relative permittivity about 7.5 and lower dielectric loss about 0.156 at 1 k Hz. The results indicate that this paper provides a new method to achieve multifunction and high dielectricity for composites. Highlight Reversible cross‐linked structures are applied in rubber / ceramic composites Cross‐linked flexible composites are reprocessable and self‐healing Reversible bonds between particles and matrix improve compatibility Synergism of BaTiO ₃ and cross‐linked structure enhances dielectric properties