Functional Group Effects on the Enthalpy of Adsorption for Self-Assembly at the Solution/Graphite Interface

The thermodynamics of self-assembly have long been explored by either experimental or theoretical investigations which are often unable to account for all the factors influencing the assembly process. This work interrogates the thermodynamics of self-assembly at a liquid/solid interface by measuring the enthalpy of adsorption encompassing analyte–analyte, analyte–solvent, analyte–substrate, and solvent–substrate interactions. Comparison of the experimental data with computed lattice energies for the relevant monolayers across a series of aliphatic analytes reveals similar ordering within the series, with the exceptions of the fatty acid and bromoalkane adsorbates. Such a discrepancy could arise when the lattice energies do not account for important interactions, such as analyte–analyte interactions in solution. Flow microcalorimetry provides a uniquely inclusive view of the thermodynamic events relevant to self-assembly at the liquid/solid interface.