The thermophoresis of a linear polymer chain in a solvent is examined theoretically and is shown to be due to the action of two forces. The first one is Waldmannʼs thermophoretic force (stemming from the departure of the molecular-velocity distribution from Maxwellʼs equilibrium distribution), which here is extrapolated to a dense medium by using scaling considerations. The second force is due to the fact that the viscous friction varies with position owing to the temperature gradient, which brings a zeroth-order correction to the Stokes law of friction. The present scaling theory is compared with recent experiments and is found to account for: (i) the existence of both signs of the thermodiffusion coefficient; (ii) the absolute magnitude of the coefficient; (iii) the fact that it is independent of the chain length in the high-polymer limit; and (iv) the dependence on solvent viscosity. The variation of the coefficient for short chains is also examined.
Eric Bringuier 1
Eric Bringuier. Thermophoresis of linear polymer chains. Comptes Rendus. Mécanique, Thermodiffusion and coupled phenomena, Volume 339 (2011) no. 5, pp. 349-354. doi: 10.1016/j.crme.2011.03.013
@article{CRMECA_2011__339_5_349_0,
author = {Eric Bringuier},
title = {Thermophoresis of linear polymer chains},
journal = {Comptes Rendus. M\'ecanique},
pages = {349--354},
year = {2011},
publisher = {Elsevier},
volume = {339},
number = {5},
doi = {10.1016/j.crme.2011.03.013},
language = {en},
}
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