IPS: An interfacial polymerization simulator for modeling the highly-cross-linked polymer membranes

The molecular mechanism of interfacial polymerization remains elusive due to rapid kinetics and nanoscale heterogeneity, while existing simulations struggle to balance chemical reactivity with computational efficiency. To address this, we developed the "Interfacial Polymerization Simulator" (IPS), an automated framework coupled with LAMMPS that models the continuous reaction-diffusion process via dynamic topology updating and explicit solvent handling. Specifically, IPS employs a novel dynamic region partitioning scheme for real-time regulating monomer concentrations. Applying this method to the m-phenylenediamine and trimesoyl chloride system, we reveal a "trunk-growth" mechanism where initial heterogeneous protrusions evolve into a dense layer with intrinsic voids. Furthermore, thermal curing simulations quantitatively reproduced structural densification (reaching ∼84% cross-linking degrees), yielding density and pore size distributions consistent with experimental benchmarks. IPS provides a robust, efficient computational tool for elucidating reaction mechanisms and guiding the rational design of functional materials synthesized by interfacial polymerization.