Interaction study between M-Phenylenediamine, Trimesoyl Chloride and Nylon 66 using Molecular Dynamic Simulation

Abstract

The thin film composite (TFC) membrane is a porous membrane layered by a polyamide active layer. In the experimental work, the polyamide active layer prepared by the interaction between monomers, m-phenylenediamine (MPD) and trimesoyl chloride (TMC) which deposited on a membrane support. Considering the possibility of producing a loose TFC membrane and affect the separation performance, this study enlightens the interaction between monomers with Nylon 6 6 (N66) support membrane using simulation - molecular dynamic (MD). Different simulation system has been investigated with varying the ratio molecule of MPD to TMC where, TFC1 (1:1), TFC2 (3:1) and TFC3 (3:2) to the tertiary system of N66/MPD/TMC. The simulation was set for a COMPASS force field, where the equilibrium phases in a microcanonical (constant volumes and total energy) (NVE) followed by run-production stage (constant pressure and temperature ensembles) (NPT) ensembles. The temperature and pressure were set at 323.15 K and 1atm respectively. The polyamide TFC was found to be formed by the main interactions between nitrogen (N) from MPD group to the carbon, (C) from TMC main chain at ranges of 4.25Å. Overall interaction can be observed between N from TFC layer with O atom from the substrate layer. All of the intermolecular interactions take place at 3.25Å distance. The best interaction in N66 to MPD and TMC system to the weakest is in the arrangement of TFC2 > TFC3 > TFC1. The highest intensity was obtained by the TFC2, indicating the best ratio of 3:1 of MPD molecules to TMC molecule with support polymer when fully polymerized occurred. This study suggests that ratio N66 to MPD and TMC in TFC2 is the best to interaction between TFC layer and substrate for fabrication of the TFC membrane.