Binding affinity between small molecules in solvent and polymer film using molecular dynamics simulations

Quantifying the binding affinity of small molecules to a polymeric film is very important in understanding the adsorption phenomenon in food industry. Here we present a model based on molecular dynamics simulations in conjunction with the Metadynamics method to reconstruct the free energy barrier for desorption of small molecules from a polymer surface. We use this technique to find the binding affinity of five small binder molecules (C8, C9, C10, Eugenol and d-limonene) to a polymeric film in water solvent that is primarily due to the van der Waals, hydrogen bonding and electrostatic interactions. It is found that the small molecule binding is a spontaneous process, the binding affinity is affected by their molecular structure and polarity, the aldehydes (C8, C9, C10) have much higher affinity than the Eugenol and the d-limonene, the binding affinity increases with a rise in temperature, and the aldehydes show higher temperature sensitivity than the Eugenol and the d-limonene. These findings suggest the possibility of using the binding affinity, especially the binding free energy, to guide the design and selection of polymeric barrier materials.