Swelling dynamics and chain structure of ultrathin PEG membranes in seawater

Polyethylene glycol (PEG) is widely utilized in marine antifouling materials; thus, the fundamental understanding of PEG characteristics in seawater is indispensable. Herein, a membrane-seawater sep-aration chamber model is designed, and the molecular dynamics (MD) method is used to simulate the swelling process of PEG membranes in seawater; two characteristic lengths are developed from the con-cept of Gibbs surface to illustrate the relationship between seawater ions and PEG membranes; the amount of bound water in the hydration shell of PEG is calculated by experimental method. It is con-cluded that the water content of the PEG membrane in seawater is not much different from that of swel-ling in water; only the swelling rate changes; the seawater ions accelerate the swelling of the PEG membrane, but most gathered in the outer layer of PEG membrane; Ions change the distribution struc-ture of the hydration layer, and the bound water of PEG decreases under the action of seawater ions. Moreover, the structure of the PEG chain in seawater has a change of helix-ring. The study of PEG in seawater will provide an effective supplement and theoretical basis for the modification design of PEG coating. (c) 2023 Elsevier B.V. All rights reserved.

Automated summary

In this study, a model was designed to simulate the swelling process of PEG membranes in seawater using the MD method. It was found that seawater ions accelerate the swelling of PEG membranes and change the distribution structure of the hydration layer and the structure of the PEG chain. This provides important insights for the modification design of PEG coatings.