Molecular simulation of polyamide synthesis by interfacial polymerization

A molecular simulation is introduced for studying polyamide film formation by interfacial polymerization (IP), a highly used method for the synthesis of separation membranes. The simulation uses a modified cluster–cluster aggregation (CCA) model to simulate polymerization of functional monomers (e.g., trymesol chloride and phenylene diamine) at an interface between two liquid phases. By controlling the partition coefficient of each monomer in the opposite phase, the film is driven to form in the organic phase, as observed experimentally. The polymer film shows a dense core with looser ends, and an inhomogeneous charge distribution. The dense core of the membrane forms quickly, followed by slow polymerization reaction that leads to further densification of the membrane core. The simulation provides a basis for studying the IP process and can be used to carry out membrane performance studies on the molecular level.