The TGA curves showed that the weight loss of VMT between 40 and 620 1C is about 7.6 wt%, which corresponds to the surface and interlayer absorbed water and part of the VMT structure (Fig. 2a). Nevertheless, the P-VMT lost about 10.4 wt% between 40 and 620 1C, of which 2.8 wt% is attributed to salt introduction in the vermiculite galleries. These results confirm the FTIR measurements, indicating that phosphonium cations are present within VMT in low concentration [9–12].