Direct Polyamidation in Molten Tetrabutylammonium bromide: Novel and Efficient Green Media

This is the first report of application of molten ionic liquid (MIL) for the synthesis of polyamides (PAs) from the reaction of dicarboxylic acids with diisocyanates. A fairly inexpensive and readily accessible MIL, tetrabutylammonium bromide (TBAB) was used for the synthesis of polymers. Therefore, polycondensation of terephthalic acid with various commercially available diisocyanates was performed in molten TBAB with or without dibutyltin dilaurate (DBTDL) as a catalyst. The polymerization reaction gave similar results in the presence or absence of DBTDL, indicating that, the catalyst was not needed in this process. Various PAs were obtained with high yields and moderate inherent viscosities ranging from 0.36 to 0.71 dL/g. This method was compared with the polymerization reaction in conventional solvent and in the presence of DBTDL as a catalyst. In the case of using TBAB, higher yields and inherent viscosities were obtained. This process is safe and green since toxic and volatile organic solvent such as N-methylpyrrolidone (NMP) was eliminated.