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

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 degrees C min(-1), 10 degrees C min(-1), and 20 degrees 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.