Before doing DLS experiment, it is recommended that one should filter their solution to get rid of dusts, or make the stock solutions clean optically by usage of filter. But when it comes to doing DLS experiments in a diluted or semi-dilute polymer sample, how exactly does one decide upon the filter size to avoid removal of polymer chains by the filter or the probe particles dispersed in the polymer solution before conducting the DLS experiment?
One such papers that I have reffered is the works done by Koike, Akihiro, Norio Nemoto, Tadashi Inoue, and Kunihiro Osaki. “Dynamic Light Scattering and Dynamic Viscoelasticity of Poly(Vinyl Alcohol) in Aqueous Borax Solutions. 1. Concentration Effect.” Macromolecules 28, no. 7 (March 1995): 2339–44. https://doi.org/10.1021/ma00111a029.
Any kind of help regarding this will be appreciated! Thank you in advance.
A 200nm membrane filter should work. Depending on the polymer concentration, filter size (diameter of the physical unit) and membrane material, you may want to prime the filter with some of the polymer solution.
Thank you for your response, John Francis Miller .
So, I am making a dilute to semi-dilute concentration solution of Poly-vinyl alcohol (PVA) and Phytagel (PHY) solution with 0.1 um diameter probe
bead size to 2um probe bead size embedded for DLS experiment.
During sample preparation, I should use the 200 nm filter to remove the dust particles from the DI water and after making the samples of PVA and PHY, pass the stock solutions of PVA and phytagel solution through 0.22 um filter before addition of probe particles? Otherwise the bigger size probe particles will get filtered out.
Lastly, how do you even figure out that the filter you are using for the stock solution doesn't end up removing the polymers?
Hi Richa Ghosh
It is probably best to first measure your sample without any filtration or any tracers. If I understand your application, you want to measure the diffusion of tracer particles in a polymer sample? Then the signal of the probe particles should be stronger than that of the "background" sample.
It is always advisable to work with clean buffer/water/solvent to prepare samples.
It will require a bit of experimental work... Good luck with the measurements!
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