IMMERSION MICROCALORIMETRY AND C-13 CP MAS NMR-STUDY OF THE STRUCTUREOF ORGANOCLAYS/

The organoclays as dimethyldistearyl ammonium montmorillonite (DDA-Mt) are interstratified clays in which pure organic sheets and silicate l ayers coexist, The stacking disorder depends on the conformation of th e DDA within the interlayer, This conformation depends on the quantity of sorbed vapor methanol, Immersion microcalorimetry of DDA-Mt in liq uid methanol data shows endothermic reactions, The CH2/CH2 bonds betwe en two adjacent alkyl chains are disrupted at P/P-0 < 0.6 correspondin g to two methanol molecules for one polar head, Beyond this value Delt a H is constant. C-13 CP/MAS NMR data show, by correlation, that the m obility of the chains is strongly increased at P/P-0 > 0.6. Mobility a nd distance between alkyl chains vary in the same direction and corres pond to an increase in the stacking order of the sheets within a parti cle. (C) 1996 Academic Press, Inc.