Molecular Dynamics Simulation of the Influence of Temperature and Salt on the Dynamic Hydration Layer in a Model Polyzwitterionic Polymer PAEDAPS

Published

September 5, 2023

Author(s)

Jennifer Clark, Vivek Prabhu, Jack F. Douglas

Abstract

We investigate the hydration of poly(3-[2-(acrylamido)ethyldimethy-lammonio]propanesulfonate) over a range of temperatures in pure water and with the inclusion of 0.1 mol / L NaCl using atomistic molecular dynamics simulation. Drawing on concepts drawn from the field of glass-forming liquids, we use the Debye−Waller parameter () for describing the water mobility gradient around the polybetaine backbone extending to an overall distance ≈ 18 Å. The water mobility in this layer is defined through the mean-square water molecule displacement at a time on the order of water's β-relaxation time. The brush like topology of polybetaines leads to two regions in the dynamic hydration layer. The inner region of ≈ 10.5 Å is explored by pendant group conformational motions, and the outer region of ≈ 7.5 Å represents an extended layer of reduced water mobility relative to bulk water. The dynamic hydration layer extends far beyond the static hydration layer, adjacent to the polymer.

Citation

Journal of Physical Chemistry B

Volume

127

Issue

38

Pub Type

Journals

Download Paper

https://doi.org/10.1021/acs.jpcb.3c03654

Local Download

Keywords

polybetaine, zwitterionic polymers, static hydration layer, dynamic hydration layer, water mobility gradients, Debye-Waller parameter, molecular dynamics

Citation

Clark, J. , Prabhu, V. and Douglas, J. (2023), Molecular Dynamics Simulation of the Influence of Temperature and Salt on the Dynamic Hydration Layer in a Model Polyzwitterionic Polymer PAEDAPS, Journal of Physical Chemistry B, [online], https://doi.org/10.1021/acs.jpcb.3c03654, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=935841 (Accessed October 13, 2025)