Synthesis and properties of strong and tough Diels–Alder self-healing crosslinked polyamides

Abstract

A new method was provided to synthesize Diels–Alder (DA) self-healing cross-linked polyamides (SH-cPAs) with high tensile strength and good self-healing efficiency. A furfurylamine-N,N’-bis(methyl propionate) (FA-BMP) was synthesized through the Michael addition of furfurylamine and methyl acrylate. Bulk polycondensation of FA-BMP with bis(2-aminopropyl) polypropylene glycol and m-xylylenediamine were conducted, and several polyamide prepolymers containing furan pendent groups (pFU-PAs) were synthesized. From a DA reaction between pFU-PAs and 1,5-bismaleimido-2-methylpentane, different SH-cPAs were prepared. The pFU-PAs were characterized by 1H NMR, 13C NMR, FT-IR, amine values, and size exclusion chromatography. The DA reaction in SH-cPAs were demonstrated by FT-IR and 1H NMR spectra. Their thermally repairing was verified with polarizing optical microscopy and tensile tests. SH-cPAs exhibits tensile strength up to 37 MPa with strain at break of 27%-164%. Their tensile strength after self-repairing was still up to 26 MPa with self-healing efficiency of 70%-92%.