Synthesis of room-temperature self-healing network polymers based on multiple metal–ligand coordination interactions

A series of novel network polymers P₁-P₆ and P_n-Zn_x:y based on metal–ligand coordination bonds with different strength were prepared by one pot method. The structures of the polymers were confirmed by NMR and FT-IR spectra. The amorphous structure of polymers was determined by X-ray diffraction analysis with only broad scattering peaks detected. The TGA and DSC showed that the increase of pyridyl group can dramatically improve the thermal stability of polymers, and T_g gradually decreases with the increase of pyridyl and pyridine groups. When the amount of Zn(II) increases, the thermal stability and the T_g gradually decreases. Optical microscope images indicated that the cross-linked network polymers P_n-Zn_1:2 all had obvious self-healing properties at room temperature, and the 50% cross-linked network P₃-Zn_1:2 and P₄-Zn_1:2 with less pyridine content have better self-healing performance. Further exploration of the self-healing properties of P₃-Zn_x:y by adjusting the molar ratio of dianhydride to Zn(II), P₃-Zn_1:4 has the best self-healing performance.