After polymerization, there are always a small amount of monomers left either in the polymer matrix or other materials that are dispersed in the polymer. This is very undesirable, as residual monomers not only make the material easily degrade, but also affect its properties.
So, how to analysis and characterize residual monomer content, and hopefully also find ways to reduce it?
using GPC and then HPLC
See this paper : : Preparation of poly(styrene-b-2-hydroxyethyl acrylate) block copolymer using reverse iodine transfer polymerization
Can depend on the polymer composition. Generally though, solvent extraction followed by GC or HPLC of the extract. Extraction can be by Soxhlet or preferably by dissolution /precipitation of the polymer --- leaving the residual monomer in solution. If you let me know the composition, perhaps I could provide more info.....
Several years ago, we noticed that a very low radiation dose can eliminate monomer residues in polymers. A US-patent was filed an accepted. The patent is now expired so, if you have access to a high energy radiation source, you can try to apply this simple method.
Usually to remove unreacted monomer from polymer the sol vent extraction is used. The polymer after extraction is analyzed by NMR and SEC. The obtained solvent extraction can be analyzed GC or HPLC or NMR (after evaporation of solvent in order to identify extracted monomer or other organic compounds present in polymer).
To be more specific, what I'm interested is a system initially prepared by mixing monomers with a liquid and a small amount of initiator. After polymerization, the liquid and polymer phase separate. In other words, the liquid is dispersed as microdroplets in a continuous polymer matrix. In this case, residual monomers in the polymer matrix in a secondary concern, the primary concern is residual monomers in the liquid droplets, which, I strongly suspect, have many undesirable consequences. It seems that in the past people tried to ignore this issue for whatever reason, but I think it has to be addressed.
So, first I have to extract the liquid (with residual monomers dissolved) from the polymer, and then find a way to analyze its components. Now I roughly have an idea of the later, but how to extract the liquid from the polymer?
Hi Dr. Zhou,
One way you can try to separate the liquid from polymer is vacuum filtration, using a vacuum pump or the old way (water trap if you don't have a vacuum pump). Then you can try either of the chromatography techniques that work better for your liquid system (I'd say HPLC). Also if you have access to TGA, FTIR or Raman, they can also be worthy of try. Specially I'd say TGA, since your liquid will likely evaporate at lower temperatures and then you might have another degradation step, if there is any residual monomer. As a benchmark, I strongly recommend to run whatever characterisation you do, on the pure liquid as well, for comparison.
Pouyan,
Thank you so much for your reply. Unfortunately, the liquid is quite volatile. Is vacuum filtration still working for this case? Also,although a secondary concern, I still want to analyze residual monomers in the polymer matrix too. I hope somebody can give me a list of references that I that can look up to.
The amount of residual monomer in the polymer is important. There are several methods. For example, head space GCMS, LCMS, solvent extraction and then HPLC, sometimes NMR can be used.
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