MOLECULAR-DYNAMICS SIMULATIONS OF TETHERED ALKANE CHROMATOGRAPHIC STATIONARY PHASES

We present molecular dynamics simulations of intermediate density diso rdered alkane monolayer systems tethered to model silica surfaces. The densities and chain lengths studied are typical of reversed phase liq uid chromatography (RPLC) stationary phases. The simulations are used to elucidate at the molecular level the complicated nature of the stru cture and dynamics of the stationary phases, which may critically affe ct the retention mechanisms of RPLC. We examine temperature, chain len gth, chain density, and surface structure effects on the chain propert ies. Also, we explore the driving forces responsible for observed inte rfacial ordering of the chain system in relation to previous simulatio ns and analytical theories. An attractive surface potential and an att ractive interparticle potential are both necessary to obtain the struc ture with the most realistic features. A corrugated surface perturbs t he chain density profile relative to that on a flat surface but does n ot appreciably affect the dynamics of the chains.