Azomethine ether-based potential curing agent for epoxy resin (diglycidyl ether of bisphenol A): Synthesis and characterization

Novel azomethine ether-based compounds (A: N-((4-(9-(4-(phenylimino)methyl)phenoxy)nonyloxy)benzylidene)bezenamine and B: N-((4-(9-(4-(p-hydroxyphenylimino)methyl)phenoxy)nonyloxy)benzylidene)-4-hydroxybenzenamine) were synthesized by condensation reaction of dialdehyde, 4,4-(1,9-nonandiyle)bis(oxy)dibenzaldehyde with aromatic amines. Structures of synthesized compounds were successfully characterized by Fourier transform infrared (FTIR), ultraviolet–visible, proton nuclear magnetic resonance imaging and photoluminescence (PL) spectroscopy. The PL spectral analysis revealed that emission maxima of compounds A and B are at 475 and 500 nm, respectively, indicate blue and green light emission with large Stokes shift range (Δλ ST, 109–138 nm). Two series of polymers: one azomethine-based polymers (C1–C5) and other without azomethine (H1–H4) were prepared by curing diglycidyl ether of bisphenol A with a synthesized curing agent (B) and commercial curing agent, respectively, in various proportions. The structural characterization of the resulting polymers was carried out by FTIR spectral analysis. Thermal properties revealed that azomethine-based polymers (C1–C5) were thermally stable up to 400°C as compared to H1–H4. The glass transition temperature of the polymers, determined by differential scanning calorimetry, was in the range 121–123°C.