Polymer substrate interactions can directly affect the thermal properties of adsorbed polymers, such as the glass transition temperature. Using temperature-modulated differential scanning calorimetry (TMDSC) and molecular modeling, we performed direct comparisons of the thermal properties and intermolecular interactions of adsorbed poly (vinyl acetate) (PVAc) and poly(methyl methacrylate) (PMMA) with similar molecular masses and adsorbed amounts on silica. Compared to their bulk counterparts, adsorbed PMMA showed a larger change in glass transition and a larger amount of tightly bound polymer compared to adsorbed PVAc. These observations suggested that the interactions between PMMA and silica were stronger than those between PVAc and silica. Molecular modeling of these surface-adsorbed polymers showed that PMMA. associates more strongly with silica than does PVAc through additional hydrogen-bonding interactions. Additionally, simulations show that the polymer-polymer interactions are stronger in PMMA than PVAc, helping explain why a PMMA mobile component is not observed in TMDSC thermograms.