Model systems of aromatic polyamide based reverse osmosis (RO) membranes were constructed by molecular dynamics simulation, where the chemical structure is demonstrated in panel a) of Fig. 1. The hydrogen bond network was investigated via clustering based on the first hydrogen shell around each cluster element, where cluster elements were set to water molecules and polymer elements demonstrated in panel b) of Fig. 1. The clustering information was used with the “Weight-Averaged Anharmonic Vibrational Analysis” method developed by us to obtain the IR difference spectra of RO membranes at various moisture conditions. Computational results were verified by comparing with experimentally obtained IR spectra, shown in Fig. 2. A peak at approximately 2700 cm<sup>-1</sup> was assigned to the O-H stretch in the carboxyl group and is thought to provide crucial information on the composition and ionization state of RO membranes, while two dips at amide I region provided information on the hydrogen bond network of amide bonds.

Investigation of reverse osmosis membranes by weight-averaged anharmonic vibrational analysis

255th National Meeting (2018)

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