Synthesis of macromolecular brush and its thermal degradation studies

Abstract

The di-1,2-propanediol ester of fumaric acid (Diol) is synthesized and polymerized to yield the macromolecular brush (PDiol). The structure of monomers and their polymer is confirmed by Fourier transform infrared spectroscopy (FTIR) studies. The PDiol material shows the number average molecular weight (Mn ) as 951 g/mol, weight average molecular weight (Mw ) as 4,378 g/mol, and a polydispersity index (PDI) of 4.6. The hydroxyl value for PDiol is 471 (mg KOH/g). The thermal degradation property of the brush is investigated using thermogravimetric analysis (TGA). The cyclic intra and inter loops are formed while annealing at a temperature of around 200 °C. Using the TG curves recorded at different heating rates and by applying advanced isoconversional methods by model-free kinetics, the apparent activation energy for the thermal degradation (Ea-D) at different reaction extents (α) are calculated and discussed. Advanced methods are also used to refine the apparent activation energy data. The Ea-D values for PDiol range from 100 to 155 kJ/mol. For a lifetime of 20,000 h, the 20% degraded PDiol can withstand a temperature of 39 °C.