Photoisomerization and thermal degradation kinetics of poly(ether–ester)s containing azomethine moiety in the main chain

Abstract

Poly(ether–ester)s containing azomethine group in the main chain were synthesized by solution polycondensation of 4,4′-bis(3-hydroxypropyloxy)-N-benzylidene aniline with adipoyl and terephthaloyl diacid chlorides. The synthesized poly(ether–ester)s were characterized by Fourier transform infrared and proton, and carbon-13 nuclear magnetic resonance spectroscopic techniques. Thermal properties were studied using thermogravimetric analysis (TGA) and differential scanning calorimetry. Thermal degradation kinetics of poly(ether–ester)s were characterized by TGA at various heating rates (5°C min⁻¹, 10°C min⁻¹, and 20°C min⁻¹). The apparent activation energy for the degradation of both the polymers was determined by three different non-isothermal model-free kinetics methods (Friedmann, Flynn–Wall Ozawa, and Kissinger–Akahira–Sunose). The photoisomerization property was examined with ultraviolet (UV) spectroscopy, and the polymer PEE1 showed a rate of trans to cis isomerization ranging 10–20 s, whereas reverse process took around 100 min in solution. UV studies suggested that this material may be used in the field of rewritable applications.