May 30, 2024, 04:16:25 PM
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Topic: Synthesis of microspheres via oil in water emulsion and solvent evaporation  (Read 2656 times)

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Offline confusedstud

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Hello, I have been trying to synthesize microspheres with Polystyrene (PS) in DCM organic phase and Polyvinyl alcohol (PVA) as an emulsifier in the aqueous phase. I have no trouble dissolving the PS, but for the PVA (98-99+% hydrolysed) no matter the molecular weight I can't seem to get a clear solution and I tried heating and even cooling the solution (saw a researchgate post and figured to try it out).

Subsequently, I mixed the two solutions together at a high spin rate of >1000 RPM. For the mid range molecular weight PVA, I managed to get some microsphere formation but with a lot of excess material. This excess material doesn't float while the microspheres do, so I presume the excess material is at least predominantly PVA which is denser than water?

Does anyone have any experience with this kind of synthesis, and if so can point out any mistakes I am making because apparently there should be 100% recovery by mass - which I am unsure if that means the weight of the microspheres should equate the weight of the PS I've added, or the total mass of the PS and PVA which is definitely not the case. And if the excess material is just excess PVA, what is a good way to get rid of it, as filtering just get the microspheres and PVA stuck together and centrifugation at 6000 rpm for 7 minutes results in some of the microspheres getting stuck in the "jelly" like excess  :-\

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