Molecular dynamics simulation of oxygen diffusion in dry and water-containing poly(vinyl alcohol)
2004 (English)In: Polymer, ISSN 0032-3861, E-ISSN 1873-2291, Vol. 45, no 11, 3893-3900 p.Article in journal (Refereed) Published
The kinetics and mechanisms of diffusion of oxygen and water in dry and water-containing amorphous syndiotactic poly(vinyl alcohol) were studied at 502 K and normal pressure by molecular dynamics simulation. Penetrant molecule trajectories were obtained in a system with 600 repeating units of poly(vinyl alcohol) and 0, 40 (2.6 wt%) and 80 (5.2 wt%) water molecules. Under dry conditions, oxygen molecules jumped in a cage-like fashion. The oxygen molecule diffused in a liquid-like fashion while water diffusion was cage-like in the system with 5.2 wt% water. The hydrogen bond lifetimes among the water molecules were significantly shorter than those formed between water and the polymer and between different polymer segments. The hydrogen bond lifetimes among all species were, within experimental error, unaffected by the content of water, even though the oxygen diffusivity increased exponentially and the water diffusivity increased to some extent with increasing water content. It seemed that the diffusivity was sensitive primarily to the decrease in concentration of polymer-polymer hydrogen bonds. which followed from the increase in water content. This finding was consonant with the analysis of the oxygen molecule motion relative to the nearest polymer backbone, which revealed that it jumped preferentially along the polymer chain and towards the backbone. This behavior was more pronounced when the dynamics were analyzed over longer distances (5 Angstrom) and it was less pronounced in the water-rich systems. The simulations indicated that water clustering was absent and consequently that water was homogeneously distributed in the polymer systems.
Place, publisher, year, edition, pages
2004. Vol. 45, no 11, 3893-3900 p.
molecular dynamics simulation, poly(vinyl alcohol), diffusion, statistical mechanical model, simple penetrants, supercooled water, high polymers, hydrogels
IdentifiersURN: urn:nbn:se:kth:diva-23424DOI: 10.1016/j.polymer.2003.12.082ISI: 000221486300037ScopusID: 2-s2.0-2342611999OAI: oai:DiVA.org:kth-23424DiVA: diva2:342122
QC 20100525 QC 20111020. Symposium on Coupling Simulations and Experiments in Polymer Science. Univ Utah, Salt Lake City, UT. MAY 15-17, 2003 2010-08-102010-08-102011-10-25Bibliographically approved