Flexible Self-healing Cross-linked Polyamides Synthesized Through Bulk Michael Addition,Polycondensation,and Diels-Alder Reaction

摘要

Three new thermally responsive self-healing cross-linked polyamides(cPA-FU-DAs)with good tensile strength and toughness were synthesized through bulk Michael addition,polycondensation,and Diels-Alder reaction.Unlike common stable polymers,cPA-FU-DAs can seal cracks by mere heating.First,the Michael addition of methyl acrylate and furfurylamine was conducted,and a furfurylamine-diester(FU-DE)was prepared.FU-DE was transformed into polyamide prepolymers that contained furfuryl pendant groups(PA-FUs)through bulk polycondensation with a poly(propylene glycol)(PPG)diamine and a PPG triamine.PA-FUs were crosslinked by bismaleimide,and cPA-FU-DAs were prepared.The Michael addition was monitored by Fourier transform infrared spectroscopy and electrospray ionization mass spectroscopy.The reverse DA reaction of the cPA-FU-DAs was demonstrated by differential scanning calorimetry and dissolution property.Their thermally self-healing properties were verified by polarizing optical microscopy and tensile test.The cPA-FU-DAs exhibited good mechanical properties and high self-healing efficiency.They self-healed at 130°C.The tensile strength after repairing was up to 19 MPa with self-healing efficiency reaching 92%.