Microgranule contains both silica and polysaccharide polymer. Want to etch silica with NaOH but don't want to disrupt the structure of polysaccharides.
NaOH can also swell polysaccharides and decrease polymerization degree. The best would be hydrogen fluoride which nearly selectively reacts with the silica.
I don't know which polysaccharides you are talking about, but all are sensitive to NaOH at different extents. For example, cellulose (i.e., linear polymer) will swell and change of structure, whereas hemicelluloses (i.e., branched polymers) will dissolve. HF will dissolve silica but I don't know the effect on your specific polysaccharide. You should do a few preliminary tests before testing HF.
Alain
Dear Debashish Sarkar
As prof. Celzard wrote, this is perfect for an experiment. You are not likely to get a precise response here without even stating what polysaccharide you are using (not speaking about its Mw, modifcation, ...), but it is easy to take your sample and put it into the NaOH solution (lets say various NaOH concentrations and times) and then analyze the effect on your sample - whether it dissolves or not plus analytical methods chosen based on the properties that you desire to preserve during the etching.
Analogous experiments can be done for HF, should it be preferable with respect to silica etching.
Regards
Josef
Thank you all for replying. The polysaccharide is gum Arabic(acacia Senegal type). It's highly branched. We have spray dried this gum with silica nano particles. Heating the spray dried granules above 300C completely removes the gum arbic keeping the structure of remaining silica intact(from SAXS analysis). Now we want to remove the silica keeping the structure of gum Arabic intact. How could we achieve that?
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