基于配位键的自修复聚氨酯制备与性能研究

Preparation and properties of self-healing polyurethane based on coordination bond

以2,6-二氨基吡啶(DAP,2,6-diaminopyridine)为扩链剂制备了功能聚氨酯预聚体(PU-DAP),采用金属离子(M为Fe^(3+),Zn^(2+)和Cu^(2+))交联PU-DAP制备基于配位键的自修复聚氨酯弹性体(PU-DAP/M).结果表明:聚氨酯引入配位键具有良好的自修复性能,交联金属离子对聚氨酯的力学性能和自修复性能有显著影响.PU-DAP/Cu^(2+)的力学强度为14.2 MPa,PU-DAP/Zn^(2+)的力学强度为7.1 MPa,两者力学强度均高于PU-DAP/Fe^(3+)(4.2 MPa),但PU-DAP/Cu^(2+)的断裂修复效率为14.8%,PU-DAP/Zn^(2+)的断裂修复效率为45.1%,都低于PU-DAP/Fe^(3+)的自修复性能95.2%.当n(DAP)/n(Fe^(3+))=2∶1时,PU-DAP/Fe^(3+)自修复聚氨酯弹性体拉伸强度为4.2 MPa,随着修复时间延长,修复效率不断提高,24 h自修复效率最高,显著高于当n(DAP)/n(Fe^(3+))=1∶1和n(DAP)/n(Fe^(3+))=3∶1的力学强度和自修复性能.通过红外光谱发现,PU-DAP与Fe^(3+)交联后,C=N振动信号从1589 cm^(-1)移至1615 cm^(-1),表明Fe^(3+)与DAP发生了配位作用,聚氨酯实现自修复源于引入的动态配位键.

In this work,the functional polyurethane prepolymer(PU-DAP)was prepared with 2,6-diaminopyridine(DAP)as the chain extender,PU-DAP was cross-linked with metal ion(M=Fe^(3+),Zn^(2+)and Cu^(2+)),and the self-healing polyurethane elastomer(PU-DAP/M)was obtained.The results show that polyurethane possessed good self-healing performance after the introduction of the coordination,the cross-linking metal ions have significant effects on the mechanical and self-healing performance of PU,the mechanical strength of PU-DAP/Cu^(2+)and PU-DAP/Zn^(2+)is 14.2 MPa and 7.1 MPa,respectively.Both were higher than PU-DAP/Fe^(3+)(4.2 MPa),however,the healing efficiency of PU-DAP/Cu^(2+)and PU-DAP/Zn^(2+)were 14.8%and 45.1%,respectively.Both were below the self-healing performance of PU-DAP/Fe^(3+)(95.2%).When n(DAP)/n(Fe^(3+))=2∶1,the tensile strength of PU-DAP/Fe^(3+)self-healing polyurethane elastomer is 4.2 MPa.As the healing time increases,the healing efficiency continuously increases,the highest self-healing efficiency was observed at 24 h,which was significantly higher than the mechanical strength and self-healing performance of n(DAP)/n(Fe^(3+))=1∶1 and n(DAP)/n(Fe^(3+))=3∶1.In infrared spectroscopy,it was found that after complexing with Fe^(3+),the vibration signal of C=N shifted from 1589 cm^(-1) to 1615 cm^(-1),which indicates that Fe^(3+)coordinates with DAP successfully,and the self-healing of polyurethane originates from the introduced dynamic coordination bond.