Temperature dependence of the diffusion coefficient of polystyrene latex spheres

✍ Scribed by Alina C. Fernandez; George D. J. Phillies

• Publisher: Wiley (John Wiley & Sons)
• Year: 1983
• Tongue: English
• Weight: 194 KB
• Volume: 22
• Category: Article
• ISSN: 0006-3525
• DOI: 10.1002/bip.360220203

✦ Synopsis

I t has long been assumed that the effect of temperature on the diffusion coefficient D , the sedimentation coefficient s , and other hydrodynamic parameters is correctly described by Walden's rule

and its extensions, i.e., hydrodynamic properties of dilute solutions of macromolecules scale linearly with temperature and antilinearly with solvent viscosity. The accuracy of this rule was extensively studied by Longsworth,' who used a Rayleigh interference technique to measure the diffusion coefficient of materials with molecular weights of 20-68,000. While one cannot show the universal applicability of a rule, over the temperature range of 1-37"C, the diffusion coefficients of the macromolecular solutes studied in Ref. 1 were found to deviate from Eq. (1) by only f4%.

Recently, Crossley et a1.2 used quasielastic light scattering (QELS) to measure the diffusion coefficient of polystyrene latex and low-density lipoprotein over the temperature range 25-50°C, finding large deviations (-0.6%/K) of D from Walden's rule. These workers also obtained the drag coefficient f of low-density lipoprotein by ultracentrifugation, finding a similar anomaly in the temperature dependence off. The paper of Crossley et aL2 thus joins a series of papers3 suggesting that QELS may not always measure the conventional mutual diffusion coefficient.