PDADMAC/PSS Oligoelectrolyte Multilayers: Internal Structure and Hydration Properties at Early Growth Stages from Atomistic Simulations

Abstract

We analyze the internal structure and hydration properties of poly(diallyl dimethyl ammonium chloride)/poly(styrene sulfonate sodium salt) oligoelectrolyte multilayers at early stages of their layer-by-layer growth process. Our study is based on large-scale molecular dynamics simulations with atomistic resolution that we presented recently [Sánchez et al., Soft Matter 2019, 15, 9437], in which we produced the first four deposition cycles of a multilayer obtained by alternate exposure of a flat silica substrate to aqueous electrolyte solutions of such polymers at 0.1M of NaCl. In contrast to any previous work, here we perform a local structural analysis that allows us to determine the dependence of the multilayer properties on the distance to the substrate. We prove that the large accumulation of water and ions next to the substrate observed in previous overall measurements actually decreases the degree of intrinsic charge compensation, but this remains as the main mechanism within the interface region. We show that the range of influence of the substrate reaches approximately 3 nm, whereas the structure of the outer region is rather independent from the position. This detailed characterization is essential for the development of accurate mesoscale models able to reach length and time scales of technological interest.

Modification of Polydiallyldimethylammonium Chloride with Sodium Polystyrenesulfonate Dramatically Changes the Resistance of Polymer-Based Coatings towards Wash-Off from Both Hydrophilic and Hydrophobic Surfaces

“…The forming coatings represent by itself a continuous film with on average four and six nm thickness on the glass and PVC substrate, respectively. These results are in good agreement with the data obtained for the PSS/PDADMAC bilayers obtained by the layer-by-layer technique of D. Kovačević et al, and the results of simulation for the multilayers from oligo-PSS and oligo PDADMAC by Sanchez et al [ 46 , 47 ].…”

Ion‐Specific Effects on Ion and Polyelectrolyte Solvation

“…Studied systems . The two common model PEs, PSS and PDADMA were chosen for the study focus because their complexes and assemblies have been extensively studied by us [15,19,29,48,81–84] and others [30,85–87] making them a well‐characterized, ideal model system for assessing the usability of AIMD as method for such systems and probing the impact of the salt type with a rigorous quantum mechanics based simulations approach. We focus on the monovalent counter ions of the PEs, Na + , K + , Cl − , and Br − , which are selected based on the salt types (KBr, NaBr, NaCl, and KCl) employed in our previous studies where we studied their effect on PEM swelling [29] experimentally and on water contents [19] by both experimental and computational means.…”

Effect of Ethanol and Urea as Solvent Additives on PSS–PDADMA Polyelectrolyte Complexation

“…We focus upon the well-studied PSS/PDADMA PE system and ethanol and urea solvent additives. This polyelectrolyte pairing has been thoroughly studied both by us ,,,− ,, and others − in water solutions, making it a well-characterized system, both experimentally and theoretically. In addition, the effects of salt on PSS/PDADMA assemblies have been examined significantly. ,,,− Also, the dynamics of water in PECs has recently raised significant interest .…”