Properties evaluation of the membranes synthesized with castor oil polyurethane and polyaniline

Polymeric membranes for electrodialysis, fuel cells, and other purposes with specific characteristics have been the focus of innumerable researches. The aim of this work was to evaluate membranes of the sulfonated polyaniline and polyurethane, obtained in the presence of the former, regarding its mechanical and electrical properties. Polyurethane (PU) was prepared from castor oil and 4-4-diciclohexilmethane isocyanate (HMDI). Polyaniline was synthesized by chemical oxidation, as described in the literature, and was sulfonated with chlorosulfonic acid in dichloroethane. Solution membranes were prepared by mixing sulfonated polyaniline (SPAN) and polyaniline doped with p-toluene sulfonic acid (PAni(TSA)) with castor oil and further HMDI. The obtained products were characterized by FTIR, TGA, and DMA. The membrane FTIR brought out the characteristic peaks of PILI and polyanilines (TSA e sulfonated), and TGA curve showed a maximum decomposition rate at 350 degrees C, quite different of the polyaniline ones. Nevertheless the SPAN/PU membrane showed very good stability until 250 degrees C. The loss modulus curves show that there was an increase in the PILI glass transition temperature with the addition of PAni and SPAN due to the their interaction with the PU chains.