I am currently working with cellulose nanoparticles. I would like to test if the polymer I am using are adsorbing or not onto their surface. There are different techniques such as Isothermal titration calorimetry (ITC), Small angle neutron scattering (SANS), Dynamic light scattering (DLS), zeta potential, H-NMR...
- Since I don't have much sample, H-NMR may be difficult to use because I have to use deuterated water.
- My nanoparticles are rodlike shaped so I don't know if DLS will capture polymer adsorption in the measurement of "hydrodynamic radius".
- I did not find any SANS facilities in Montreal...
- ITC seems very difficult to handle (the experiments itself) and may not be that reliable for such use. I may be mistaken here since I don't know much on this technique.
- Viscosimetry is another method but usually have to come with another method since it gives clues, not real proof.
Thank for the help in advance!!!
Why not use chemistry? You measure the change in concentration of polymer in solution after contact with the nanoparticles.
You need: 1) a reliable analytical method for the concentration of polymer in solution; 2) A way of removing nanoparticles from solution (centrifugation or filtration). Procedure: i) Add nanoparticles to a polymer solution of known concentration; 2) Remove nanoparticles from solution; 3) Measure polymer concentration in the solution with nanoparticles removed. If the concentration is less than the initial concentration, then adsorption has occurred. This is how we measure polymer adsorption isotherms.
Solution concentration could be measured by Total Organic Carbon, spectroscopy (UV or IR) or via some colorimetric reaction. It depends on your polymer.
Maybe DLS will not capture the hydrodinamic radius changes after polymer absorption, but probabbly the Z-potential of nanorods will be affected, so if you have a DLS able to measure z-potential, you should check.
Both Dr. Parker and Dr. Taglietti have great suggestions. To add on to Dr. Taglietti's answer, if you use DLS and the NPs interact differently with the solvent/themselves due to a change in Z-potential, you might see a change in hydrodynamic diameter after all. However, DLS disproportionally picks up the largest particles in solution so if you have a large heterogeneity in aggregate size you might not see a difference.
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