MOLECULAR-DYNAMICS SIMULATIONS OF ORGANICALLY MODIFIED LAYERED SILICATES

Molecular dynamics (MD) simulations are used to study the static and d ynamic properties of 2:1 layered silicates ion exchanged with alkyl-am monium surfactants. These systems are in the form of oligomeric alkane s grafted by cationic groups on atomically smooth crystalline layers 1 0 Angstrom thick and several microns wide. The organically modified la yers self-assemble parallel to each other to form alternating, well-or dered organic/inorganic multilayers. By studying the systems at the ex perimentally measured layer separations, computer modeling directly pr ovides the structure and dynamics of the intercalated surfactant molec ules. The grafted-chain conformations are also expressed through the t rans-gauche conformer radios and transition frequencies which compare well with Fourier transform infrared spectroscopy (FTIR) experiments. (C) 1998 American Institute of Physics.