Multicomponent diffusion in crowded solutions. 1. Mutual diffusion in the ternary system poly(ethylene glycol) 400-NaCl-water

Citation
A. Vergara et al., Multicomponent diffusion in crowded solutions. 1. Mutual diffusion in the ternary system poly(ethylene glycol) 400-NaCl-water, MACROMOLEC, 34(4), 2001, pp. 991-1000
Citations number
87
Categorie Soggetti
Organic Chemistry/Polymer Science
Journal title
MACROMOLECULES
ISSN journal
00249297 → ACNP
Volume
34
Issue
4
Year of publication
2001
Pages
991 - 1000
Database
ISI
SICI code
0024-9297(20010213)34:4<991:MDICS1>2.0.ZU;2-Q
Abstract
The multicomponent approach in the description of molecular diffusion takes into account the correlation of motion between solutes. Here it is shown t hat this approach is necessary to describe correctly the flows of each comp onent in concentrated solutions of macromolecules, defined "crowded solutio ns". Microscopic intuitive considerations make clear this necessity also fo r hypothetical uncharged hard particles. We present precise measurements of mutual diffusion coefficients relative to five compositions of the ternary system poly(ethylene glycol) (PEG) 400-NaCl-water, changing both the PEG a nd salt concentrations. The values of the experimental diffusion coefficien ts for this system seem to be dominated by an excluded volume effect. Our r ecent predictive equations, proposed to evaluate the diffusion coefficients in a ternary systems of hard sphere solutes, have been tested on the exper imental data with reasonable success. The thermodynamic and gravitational s tability analysis on the collected data is also reported. By changing the c hoice of solvent constituent from water to PEG or NaCl, it is clear that th e counter-flow related to the polymer flux in crowded solutions is due esse ntially to the water and not to other constituents.