Fitting the Temkin adsorption isotherm to intermediate concentrations for each OFM, we obtain an experimental estimate of the adsorption energy, see Figure . This approach yields and adsorption energy of -24.9 kJ mol -1 for GMO (α = 13.1) and -33.2 kJ mol -1 for GMS (α = 15.5). These values are the same order of magnitude as the computational results calculated through the adsorption PMF of each OFM, see Table . The agreement between the computational and experimental results is much better for GMS than for GMO and the α value found for both OFMs is the same. One would expect to find different α values if different chain packing efficiencies lead to reduced dispersion forces between adsorbed molecules in the case of GMO and thus lower coverage. This was the case with SA and isosearic acid reported by Jahanmir and Beltzer, 20 in which the presence of the methyl side group decreases packing efficiency and thus dispersion forces. They found a different slope m and therefore a different α for both surfactants. The same authors, however, ascribed the differences in coverage between SA, elaidic acid and oleic acid to changes in chain dispersion interaction even though they found similar values of α for the three surfactants.