Preparation of High Mechanical Performance Polyimides by Microbranched Cross‐Linked Structures

ABSTRACT To improve the modulus and tensile strength of polyimide films, this study utilized diamines with amide bonds as monomers, introducing hydrogen bonding into the material. Additionally, a microbranched cross‐linked structure was created by incorporating a triamino compound, and its effect on film properties was analyzed. The results showed that the microbranched cross‐linked structure and amide bonding significantly improved the storage modulus, tensile strength, shape memory properties, and toughness of the polyimide films. Specifically, at 2% concentration of 1,3,5‐tris(4‐aminophenoxy)benzene, the storage modulus of the polyimide films reached 12.97GPa, the tensile strength was 243 MPa, the elongation at break was 5.58%, and the toughness was improved by 2.59 times. At this concentration, the shape fixation rate of normal polyimide was 96.7%, and the shape recovery rate was 92%. These findings suggest that the modified polyimide films exhibit high strength and are suitable for applications in high‐temperature environments.