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 <i>T</i>_g ranging from 37 to 61 °C, tensile strength up to 71 MPa, and strain at break of about 11%