2025, Vol. 6, Issue 2, Part B

Aromatic polyesters are valued for their thermal stability, mechanical strength, and chemical resistance but suffer from poor solubility and limited processability due to rigid backbones and strong intermolecular interactions. To address this, two novel diols—3, 5-dihydroxy-N-(4-(naphthalen-8-yloxy) phenyl) benzamide (XV, 1-naphthyl) and 3, 5-dihydroxy-N-(4-(naphthalen-7-yloxy) phenyl) benzamide (XVIII, 2-naphthyl)—were synthesized and polymerized with IPC and TPC via interfacial polycondensation.

The polyesters exhibited inherent viscosities of 0.35-0.54 dL/g, confirming moderate-to-high molecular weights. They were highly soluble in polar aprotic solvents (NMP, DMF, DMSO, DMAc) but poorly soluble in chloroform and dichloromethane. XV-based polyesters showed better solubility than XVIII analogues, consistent with greater chain disruption. XRD analysis revealed amorphous structures with broad halos at 2θ = 15-25°, confirming reduced chain packing due to bulky pendant groups.

Overall, pendant orientation strongly influenced solubility and structural order: XV polyesters were more soluble and amorphous, whereas XVIII polyesters were more compact and less soluble. These insights highlight pendant design as a key strategy for tailoring polyesters for coatings, membranes, and composite applications.