The alternate adsorption of polycations and polyanions on a substrate yields multilayer structures that have highly adaptable properties. These polyelectrolyte multilayers (PEMs) have promising applications in batteries, drug-delivery and protective coating systems. The three major components of PEMs are polymer, water and salt ions, all of which largely influence the PEM properties. In this talk, we discuss the influence of salt and polyelectrolyte on the water content of the PEM- specifically, the water associated with the polycation-polyanion (intrinsic) ion pairs, “i”. Attempts to quantify i for polyelectrolyte systems are few and complex. Here, using quartz crystal microbalance with dissipation (QCM-D), we monitor both the in-situ layer-by-layer deposition of poly(diallyldimethylammonium)/polystyrene sulfonate (PDADMA/PSS) PEMs and the swelling and deswelling responses to varying ionic strengths. Using ellipsometry in addition to QCM-D, we determine values of i for PDADMA/PSS PEMs. These results provide an understanding of water and ion-pair relationships and aim to provide a universal technique for all PEM systems.

Quantifying water-ion pair interactions in polyelectrolyte multilayers using quartz crystal microbalance with dissipation

ACS Spring Meeting 2021

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