New polyamides with long alkane segments: nylon 6.24 and 6.34

Abstract

A series of new amphiphilic, semi-crystalline polyamides based on hexamethylenediamine and long alkane carboxylic diacids has been synthesized and characterized, here exemplified by polyamide 6.24 (PA-6.24) and polyamide 6.34 (PA-6.34). The polymers were produced by melt polycondensation, which yielded materials of weight-average molecular weights in the range of 30,000–35,000 g/mol. The thermal properties of the polyamides were investigated by various thermo-analytical methods. PA-6.24 and PA-6.34 exhibit relatively high melting temperatures of 189 and 177°C, respectively. Both materials display rather poor solubility in solvents that are used for common polyamides, but by contrast, dissolve in, e.g. ethanesulfonic acid. PA-6.34 was found to aggregate in dilute methanesulfonic acid solutions and form thermo-reversible gels in H 2SO 4, which we attribute to its amphiphilic character. The latter enabled the use of PA-6.34 as a “compatibilizer” for blends of polyolefins and polyamides. Finally, the Young's moduli of isotropic films of PA-6.24 and PA-6.34 were determined to be 1.3 and 0.7 GPa, respectively, representing a stiffness that is intermediate between that of common polyamides and polyethylene.