  The Casimir-Polder force is an important long range interaction involved in
adsorption and desorption of molecules in fluids. We explore Casimir-Polder
interactions between methane molecules in water, and between a molecule in
water near SiO2 and hexane surfaces. Inclusion of the finite molecular size in
the expression for the Casimir-Polder energy leads to estimates of the
dispersion contribution to the binding energies between molecules and between
one molecule and a planar surface.
