Molecular dynamics simulation of the PEO sulfonic acid anion in water

Atomistic molecular modeling has been used to study the sulfonic acid anion of poly(ethylene oxide) (PEO sulfonic acid anion) in vacuum and a polymer electrolyte system consisting of the PEO sulfonic acid anion in water. The vibrational spectra of the molecules were simulated by the local mode metho d and found to be in good agreement with the experimental IR and Raman spec tra. The structure of PEO sulfonic acid anion was studied in vacuum and wat er and compared to the structure of an isolated PEO sulfonic acid in vacuum . The simulated value for the root mean square end-to-end distance for the PEO sulfonic acid anion was 22 Angstrom in vacuum and 12 Angstrom in water. The root mean square radius of gyration of the PEO sulfonic acid anion was 8.4 Angstrom in vacuum and 5.6 Angstrom in water. The PEO sulfonic acid an ion was randomly coiled in water and in an extended shape in vacuum. (C) 20 00 Elsevier Science Ltd. All rights reserved.