Molecular conjugation and crystallinity impact of designed novel chalcone based polyesters and polyesteramides on their thermal-electrical conductivity

Abstract

Two polyesteramides were synthesized via polycondensation reactions involving 4′-amino-4-hydroxychalcone 3a with succinic acid (4) and terephthalic acid (5), utilizing phosphoryl chloride as a chlorinating agent. A parallel reaction with (E)-1,3-bis(4-hydroxyphenyl) prop-2-en-1-one chalcone (3b) yielded two polyesters under identical conditions. The resultant polymers were obtained with excellent yields ranging from 93 % to 98 %. Characterization of the obtained polyesteramides and polyesters was conducted using various analytical techniques. Fourier-transform infrared spectroscopy (FTIR) evidenced the disappearance of the OH group's broad band from the initial monomers, providing strong support for polymer formation. Thermal gravimetric analysis (TGA) results indicated high thermal stability of all prepared polymers at elevated temperatures, designating them as potential thermoplastic polymers. Powder X-ray diffraction (XRD) outcomes demonstrated a significant amorphous nature for all synthesized polymers, with degrees ranging from 67.56 % to 74.75 %. Analysis of current/voltage (I-V) curves revealed a wide spectrum of electrical conductivity for polymers containing chalcone in their repeating units, ranging from negligibly low values of 0.08 µS/cm to 0.31 μS/cm, indicating their potential as semiconducting materials. Variations in conductivity across synthesized polymers were attributed to the degree of conjugation in polymeric chains and their crystallinity levels.