A combined study on intermolecular interactions between polystyrene and d-limonene utilizing light-scattering experiments and computational simulations

To quantitatively evaluate the solvent quality of d-limonene for polystyrene, light-scattering experiments were performed on polystyrene in d-limonene. Molecular-level information on the intermolecular interactions between the repeat unit of polystyrene and d-limonene was obtained by means of computational simulations. From the light-scattering experiments, the mean-square radius of gyration 〈S²〉 values for atactic polystyrene (a-PS) with weight-average molecular weights ranging from 3.73 × 10⁴ to 2.87 × 10⁶ in d-limonene at 25.0 °C were determined to be between those in toluene, a good solvent, and those in cyclohexane, a poor solvent. Moreover, the second virial coefficient A₂ values of a-PS in d-limonene were smaller than half of those in toluene. The 〈S²〉 and A₂ values were analyzed according to the helical wormlike chain model, and the binary-cluster integral β, representing the magnitude of the excluded volume between constituent segments of a-PS, was found to exhibit an intermediate value between those in toluene and cyclohexane, confirming that d-limonene is a medium solvent for a-PS. The intermolecular interaction energy between cumene as a model compound representing the repeat unit of polystyrene and d-limonene, which was obtained from the computational simulations, supported the estimated solvent quality for polystyrene.