Functionalization of nanoclays through exchange reactions

A cationic clay (sodium-montmorillonite, MMT) and an anionic clay (hydrotalcite, HT) were treated with two phosphonium based ionic liquids (ILs) and a commercial corrosion inhibitor. Clay modification was examined by TGA, FTLR and WXRD. The cationic clay modified with both ILs had similar thermal stabilities since they contained the same cation although the original anions were different. The thermal stability of the modified clays was higher than that of a commercial organoclay and of clays modified in our group with smaller MW pyridinium and imidazolium based cations. 10 wt% of interchanged cation was found under selected time/temperature treatment conditions. Clays modified with the long chain phosphonium based ILs showed excellent dispersion in a PP matrix, by contrast to the poor dispersion of clays modified with smaller MW imidazolium and pyridinium cations. MMT was also modified with a cationic corrosion inhibitor. FTIR, TGA, WXRD results suggest intercalation with its cation. Accelerated corrosion tests on steel panels coated with a paint containing MMT/inhibitor combinations showed better protection than paints containing either clay or corrosion inhibitor. By contrast to the cationic clay, attempts to intercalate a large organic anion from [THTDP] [DE] were not successful, as suggested by WXRD data. Possible reasons are provided