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

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.