Synthesis, Characterization, and Optical, Electrical and Thermal Stabilities of Poly(phenoxy-imine)s Containing Methyl and Hydroxyl Groups

The four different Schiff base compounds were synthesized from condensation reaction of benzaldehyde, 2-hydroxybenzaldehyde, 3-hydroxybenzaldehyde and 2-hydroxy-1-napthaldehyde with 4-amino-3-methylphenol. Then, the Schiff bases were converted into poly(phenoxy-imine)s by oxidative polycondensation in aqueous alkaline medium using NaOCl as oxidant. The structures of synthesized monomers and polymers were determined by Fourier transform infrared, proton-carbon-13 nuclear magnetic resonance (H-1-C-13-NMR) and ultraviolet-visible (UV-Vis) spectroscopies. The surface morphology of poly(phenoxy-imine)s was determined by scanning electron microscopy images. The molecular weight distributions of poly(phenoxy-imine)s were studied with gel permeation chromatography measurements. The optical properties of compounds were determined from UV-Vis spectroscopy and fluorescence spectroscopy measurements. Electrochemical properties of the compounds were determined by cyclic voltammetry analysis. The solubility tests of the synthesized compounds were performed in various organic solvents. Thermal properties of the compounds were determined by thermogravimetric and differential thermal analysis and differential scanning calorimetry. The electrical conductivity of undoped and iodine-doped poly(phenoxy-imine)s was measured by four-point probe technique at room temperature. The synthesized poly(phenoxy-imine)s show good electrical conductivity with iodine doping and the conductivity increases with the increase in iodine vapor contact time.