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In this study, generalized predictive models were developed to estimate K OA of four kinds of aromatic pollutants based on the calculated solvation free energy and taking the dimer effect into account. Uncorrected log K OA values, which were directly estimated from the calculated solvation free energy of individual molecules, underestimated experimental values, and the deviation increased with increasing log K OA. Dimers were found to greatly affect the apparent K OA values of these aromatic pollutants, which were driven by π-π interactions. London dispersion and exchange-repulsion terms were identified to be dominant components of the underlying π-π interactions. It is interesting to find that the π-π interactions of polybrominated diphenyl ethers correlate with not only the molecular polarizability but also the size of opposing aromatic surfaces, which leads to a different trend of π-π interactions from other aromatic pollutants. A universal quantitative structure-activity relationship model was developed to estimate the proportion of dimers based on five molecular structural descriptors relevant to the π-π interactions. After calibration with the dimer effect, estimations of log K OA were consistent with experimental values. Therefore, the dimer effect should be taken into consideration when investigating the partition behavior of aromatic pollutants, and the solvation free energy model could be an alternative method for the prediction of K OA. [Display omitted] • Generalized predictive models were developed for K OA of aromatic pollutants. • The underlying π-π interactions for the formation of dimers were dissected. • A universal QSAR for dimer percentages was developed based on the π-π interactions. • The dimer effect on the estimation of log K OA was analyzed and amended. [ABSTRACT FROM AUTHOR]