Preparation and characterization of self-healing polyurethane based on Fe3+coordination bond
In order to improve the mechanical properties and self-healing ability of polyurethane(PU)film,a series of self-healing PU(PU-DAP/Fe3+)films were synthesized from PU coordination crosslinking of Fe3+with sample(PU-DAP),which were prepared using isophorone diisocyanate,polypropylene glycol,poly(1,4-butylene adipate)as raw materials,2,6-diaminopyridine(DAP)as main chain extender.The formation of metal coordination bonds in PU-DAP/Fe3+film was characterized by FTIR and XPS.The thermal stability of PU-DAP/Fe3+films were tested by TGA and DSC,and their self-healing properties(mechanical properties,self-healing efficiency)were evaluated.The self-healing ability and phase separation of PU-DAP/Fe3+films were further analyzed by polarizing microscopy(POM)and AFM.The results showed that Fe3+coordinated with DAP and nitrogen as well as oxygen on the amide group,forming a coordination cross-linking structure,which effectively improved the thermal stability of PU-DAP/Fe3+.When n(DAP)∶n(Fe3+)=2∶1,the prepared PU-DAP/Fe2∶1 3+film exhibited the best mechanical properties and self-healing properties,with a thermal decomposition temperature of 17.15 ℃ higher than that of PU-DAP,and tensile strength and self-healing efficiency of 5.16 MPa and 93.2％,respectively.The scratches almost disappeared after 36 h repair at room temperature.The reason was that the strong and weak Fe3+coordination bonds introduced in the PU-DAP system and weak hydrogen bonds between molecular chains could be dynamically broken and recombined at room temperature to form a new network structure.In addition,the lower glass transition temperature(-48.3 ℃)ensured the flexible movement of the molecular chain at a lower temperature,prompting the broken metal coordination bond to re-associate and return to a near original state.
万方数据
