Abstract:A series of indole-based poly(hexahydrozine) (IN-PHT) flexible film materials were prepared by simple copolymerization of tryptamine (Tryp), poly(propylene glycol) bis(2-aminopropyl ether) (D-400), and paraformaldehyde, and the films were soaked in MgCl2 solution to prepare Mg-poly(hexahydrozine) (Mg-IN-PHT) film crosslinked by Mg2+-indole interaction. The uniform distribution of Mg2+ in Mg-IN-PHT was confirmed by EDS. The formation of cation-π interaction between Mg2+ and indole were demonstrated by UV, RF and theoretical calculation. The mechanical properties of Mg-IN-PHT films were characterized by cyclic tensile tests. The results indicated that Mg-IN-PHT films had stronger tensile strength (16.1 MPa) and toughness (206.2%), which were significantly higher than IN-PHT films (11.0 MPa, 117.0%). On the one hand, cation-π cross-linking increased the cross-linking density, thus enhancing the strength of film; On the other hand, the molecular chains of flexible polymer network slips easily when it was externally stimulated. So that the "point-surface" cation-π interactions could be formed and released more easily, and the energy dissipation effect was better, thus the toughness of film was improved. In addition, the thermal stability of Mg-IN-PHT was also investigated. The results indicated that the thermal decomposition temperature (280°C) and Tg (-10°C) of Mg-IN-PHT films were higher than that of IN-PHT films (234°C) and (-16°C). Finally, the dynamic “point-surface” cation-π interaction endowed Mg-IN-PHT films with excellent self-healing and recycling ablities.