The Mixing Behavior of Alkanes Adsorbed on Hexagonal Boron Nitride

High Resolution Image Download MS PowerPoint Slide In this work, we report the mixing behavior of a series of normal alkanes adsorbed on the surface of hexagonal boron nitride (h-BN) using X-ray powder diffraction. We have investigated a range of simple binary mixtures which are indicative of a rich phase behavior with examples of complete mixing, partial mixing, and phase separation. On graphite surfaces, the mixing behavior is strongly influenced by the structure of the pure components; the odd–even effect seen in the pure structures, which favors either a “herringbone” or a “parallel” structure, influences the miscibility of alkanes within the monolayer. On h-BN, a more complex phase behavior is observed with partial mixing or phase separation depending upon the exact composition of the monolayer. In particular, we see improved miscibility for certain mixtures containing n -decane which we associate with the fact that pure n -decane has been observed with both herringbone and parallel structures on h-BN. This difference between these two very similar substrates is a sensitive indicator of the subtle interplay between surface–molecule and molecule–molecule interactions that govern the phase behavior of these systems.