Cross-Linked Polyamides Synthesized through a Michael Addition Reaction Coupled with Bulk Polycondensation

Abstract

A simple route is described to synthesize cross-linked polyamides (cPAs) with excellent mechanical properties at mild conditions through a Michael addition reaction coupled with bulk polycondensation. A Michael addition of methyl acrylate with 1,6-hexanediamine was conducted in a bulk state at a N–H/C═C molar ratio of 1:1 under normal pressure at 50 °C, and a hexanediamine-tetraester was prepared. Bulk polycondensation of the hexanediamine-tetraester with 1,6-hexanediamine and isophoronediamine was conducted at 170 °C for 1 h and then in tetrafluoroethylene mold under reduced pressure for another 8 h. A series of cPA films were prepared. The Michael addition and the polycondensation were monitored by Fourier transform infrared, 1H NMR, and electrospray ionization mass spectrometry spectra. The cPA films were characterized with differential scanning calorimetry, thermogravimetric analysis, dynamic mechanical analysis, and a tensile test. These cPAs exhibited Tg ranging from 37 to 61 °C, tensile strength up...