Modeling the Activity of Wax Inhibitors: A Case Study of Poly(octadecyl acrylate)

Abstract

The role of poly(octadecyl acrylate) in inhibiting wax formation and growth has been examined using both molecular dynamics and Monte Carlo methods. The simulations show that the defective wax growth identified in earlier studies4,6 has a simple energetic basis and indicates that the comblike polymeric inhibitors favor the formation island defects on the wax surface. These island defects have weak interactions with the surrounding crystal, and so act as impurity sites for blocking growth steps. Using the information gained from molecular dynamics simulations of wax growth at a wax/liquid heptane interface, we have generalized recent Monte Carlo growth methods to provide a realistic yet simple model of wax inhibition. The model predicts that poly(octadecyl acrylate) will prevent growth at low supersaturations, where growth occurs largely at step defects, and slows growth at higher supersaturations, where island nucleation is important.