Development and analysis of polyamides derived from 2,6-diaminopyridine and 1,4-phenylenediamine

Aromatic polyamides are an important class of high-performance polymers; however, achieving a balance between rigidity, processability, and tunable physicochemical properties remains a challenge. In this study, two structurally related aromatic polyamides (PAM and PAM-2) were synthesized via Yamazaki-Higashi phosphorylation polycondensation using a bisphenol-A-based diacetic acid monomer and two different diamines, namely 2,6-diaminopyridine and 1,4-phenylenediamine. The synthesized polymers were comprehensively characterized by FTIR, ¹H NMR, XRD, FESEM-EDAX, elemental mapping, GPC, inherent viscosity, contact angle measurements, tensile testing, and thermal analysis (TGA/DTG). The results confirmed successful polymer formation with moderate molecular weight and narrow distribution. Both polymers exhibited amorphous nature and good solubility in polar aprotic solvents. Comparative analysis revealed that the incorporation of pyridine units in PAM enhances intermolecular interactions, leading to improved tensile strength (∼38 MPa), good thermal stability, and enhanced char residue (∼40% at 800 °C). In contrast, PAM-2 showed comparatively lower mechanical and thermal performance but exhibited more compact morphology and reduced surface wettability (contact angle ∼90°). These findings demonstrate that subtle variations in diamine structure significantly influence the structure-property relationship of aromatic polyamides. This work provides useful insights into the rational design of polyamide materials with tunable properties, while potential applications are suggested cautiously and require further investigation.