Synthesis of new carbohydrate-based polyurethanes and their application in the purification of methyl esters (biodiesel)

The development of new urethanic materials from renewable resources has aroused great interest in the scientific community due to their higher sustainability and biodegradability. In this work, the synthesis and characterization of carbohydrate- based polyurethanes are demonstrated. Reactions were carried out with toluene diisocyanate (TDI) in dimethylsulfoxide (DMSO) using starch, cationic starch and a commercial maltodextrin with a dextrose equivalent value of 18.1. The polyurethanes were obtained as white powders with yields ranging from 36 wt.% to 43 wt.%. Textural properties evaluated by the BET method showed that the polyurethanes can be classified as mesoporous materials. FTIR analyses of the resulting polymers revealed the appearance of a urethanic carbonyl band at 1716-1718 cm(-1). The polymers showed a typical two-step thermal decomposition by TGA and the Xray diffraction patterns indicated a predominantly amorphous character. Formation of urethane linkages was also demonstrated by solid-state C-13 NMR of the maltodextrin/TDI polyurethane. These data suggest that carbohydrate- based urethanic materials were successfully synthesized. Furthermore, these polymers were shown to be suitable for biodiesel purification since they were able to reduce the amount of fuel contaminants such as soaps and acidity.