the depletion interaction has been proved exist in colloidal system, I am thinking whether it exist between different polymer or the same polymer with different molecular weight ?
@Tihomir Nikolaev Tsanov thank you for your answer. if I mixed two PEO with different molecular weight in water： one is about 35000 and the other is 1000000，beside the percent of high molecular weight one is higher than the other one， will the low molecular weight one be compacted due to the depletion？
depletion is actually about competition for solvent molecules. Therefore it exist between particles - polymer, particles - particles and polymer - polymer. It also exists for emulsions in micellar solutions. Above cmc first largest droplets will be flocculated.
Practically for a mixture of polymers with only difference in degree of polymerization up-to high polymer concentrations you should not observe any effect, only when there is not enough solvent for full solvation.
@Titus Sobisch, thank you for your help.Once a paper named "How does solvent molecular size affect the microscopic structure in polymer solutions?" (http://aip.scitation.org/doi/full/10.1063/1.2213610) described about the effect of middle-sized solvent. So I am confused the if the depletion exist for a mixture of same polymer with different degree of polymerization.
Dear Kuo,
deduced from the abstract, article is not about depletion interaction. And it is a simulation for cases not common, when solvent itself is a polymer larger or in the order of size of solute.
@Titus Sobisch, sorry I missed the intention, it is absolutely not about depetion interaction.this paper is about solution, the middle-sized solvent is also solute. As the origin of depletion is entropy effect, it is also entropy effect induces Rg changing with different size of big slovent. From this point of view, depletion can't be judged exist or not in the system in this paper.
If you want to experimentally observe such effect, you may try adding oligomer into polymer in (near) theta or athermal solvents. The simulation was motivated from the addition of oligomer can promote the self-seembly of polymers, which was conducted by Prof. Gi Xue (Nanjing Univ.). Good luck!
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