Mesoscale computer modeling of asphaltene aggregation in liquid paraffin.

This article focuses on the development and application of a refined coarse-grained Martini model to study the aggregation behavior of asphaltene molecules—aromatic compounds with polycyclic cores and aliphatic side groups—in liquid paraffin. The model was calibrated against atomistic simulation data to realistically capture asphaltene dimerization and allowed the simulation of thousands of molecules over microsecond timescales. Findings indicate that native asphaltenes with aliphatic side chains form small, uniformly distributed clusters with lower mobility due to mixing with paraffin, while chemically modified asphaltenes lacking aliphatic periphery form larger, stacked aggregates that can overlap and phase-separate at high concentrations, with aggregate size dependent on system size. The study also compares results from two atomistic force fields (CHARMM36 and GAFF), highlighting differences in aggregation behavior and emphasizing the importance of system size and chemical structure in interpreting simulation outcomes relevant to applications such as polymer nanocomposites and thermal energy storage.