Synthesis and characterization of ultra‐tough crosslinked polyamide with hybrid polymer networks equipping strong hydrogen bonds.

In this work, a novel crosslinked polyamide (cPA) system with hybrid polymer networks was developed. The hexamethylenediamine, acrylic acid (AA), and bis(6‐aminohexyl) dodecanediamide (BAHD) were utilized as the main building block in crosslinked polyamide (cPA) system by Michael addition reaction and polycondensation, wherein an amide diamine monomer, BAHD, was utilized as the building provider of hydrogen‐bonding networks. Simultaneously, the internal covalent bond networks were constructed by the Michael addition between AA and diamine, resulting in permanent covalent crosslinks. By adjusting the ratio of BAHD content, a series of copolyamides were successfully synthesized, and the thermal, mechanical, and viscoelastic behavior of cPAs were systematically discussed. Based on these results, the best mechanical properties in our cPAs were found in the composition of BH37, which exhibited microcrystalline behavior and outstanding tensile properties with melting temperature of 55°C, tensile strength above 45 MPa, and elongation at break above 1000%. It demonstrated that the adjusting of reversible hydrogen bonds and permanent covalent crosslinks in hybrid polymer networks could effectively endow the cPAs with excellent flexibility and strength. These studies provide useful information for designing novel cPA materials with controlled thermal and mechanical properties, which suggested the potential for use in advanced application fields. [ABSTRACT FROM AUTHOR]