Hildebrand solubility parameters are predicted from molecular simulations using the transferable potentials for phase equilibrium-united atom (TraPPE-UA) and Dreiding force fields for the n-alkyl acrylate and methacrylate esters (n ≤ 10), as well as the 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, isooctyl esters of acrylic acid, and the 2-hydroxyethyl ester of methacrylic acid. The TraPPE-UA force field yields very accurate solubility parameters (with a mean unsigned percent error of 2% or 0.2 Hildebrand units), whereas the Dreiding force field overpredicts the solubility parameter in every case examined. Correlations based on the normal boiling point or the refractive index do not yield satisfactory results for this monomer set with the former overestimating the magnitude and the latter yielding the incorrect sign for the decrease in the solubility parameter with chain length. Simulations with the TraPPE-UA force field yield solubility parameters for binary mixtures of methyl methacrylate with 2-ethylhexyl or isooctyl acrylate, which are very well described by a linear interpolation using the pure compound cohesive energies and molar volumes, whereas those for mixtures with 2-hydroxyethyl acrylate or methacrylate small positive deviations due to structural microheterogeneity.
- Monte Carlo simulations
- Solubility parameter