Microwave-assisted rapid synthesis of a polyether from a plant oil derived monomer and its optimization by Box-Behnken design

Abstract

In this study, a new strategy for making polyethers from α-olefin (1-decene) was developed using microwave irradiation and compared with a conventional method. The olefin was epoxidized and subjected to catalytic polymerization using both conventional and microwave synthesis techniques. The conventional epoxidation reaction of 1-decene took 1 hour while microwave-assisted epoxidation was completed in ∼5 minutes. A three-factor, three-level Box-Behnken response surface design was employed to investigate the effect of the process parameters such as time, temperature, and the solvent-monomer ratios on the yield of the ring-opening polymerization of 1,2-epoxydecane using MMAO-12/2,4-pentanedione. The obtained experimental data were fitted to a transferred second-order polynomial equation using multiple regression analysis with a high coefficient of determination (R2) value of 0.9881. Interestingly, the optimal predicted parameters based on all independent variables (reaction time 9.97 min, the temperature 99.69 °C, and solvent to monomer ratio 5.27:5) were determined by a maximum polyether yield of 82.51%, which was further confirmed by validation experiments. The synthesized polymers were characterized by using proton nuclear magnetic resonance spectroscopy (1H-NMR), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA) and size exclusion chromatography (SEC). A high molecular weight polyether was synthesized with a melting temperature as high as 88.64 °C and a decomposition in the range of 325-418 °C. The rapid synthesis of a biopolyether with high molecular mass is extremely attractive both from an academic and industrial point of views.