I am going to perform a polymerization of Ɛ-Caprolactone using different polyols (trimethylolpropane and pentaerythritol) as initiators, catalyzed by tin(II) octoate. I know that I must dry glassware in the oven. I believe a vacuum distillation of CL would be enough to make sure it doesn't contain excessive water/impurities, can anyone confirm such a method or suggest a better one? Furthermore, after the polymerization, I'll need to purify the PCL. I have read about a first dissolution in dichloromethane followed by dropwise pouring in excess petroleum ether causing precipitation. Filtration and drying would then yield the purified PCL. Do you recommend a different course of action or do you have any suggestions?
Thanks in advance
Dear Lorenzo Papini, distillation is the most used technique for caprolactone purification. Please check the following links. My Regards
https://patents.google.com/patent/US5994565A/en
https://www.researchgate.net/post/Purification-of-epsilone-caprolactone-prior-to-polymerization
https://pubmed.ncbi.nlm.nih.gov/29648706/
With vacuum distilling I've obtained PCL of more than 1,000,000 g/mol. For oligomers (below 10k) I don't even bother and use straight from the bottle.
PCL purification would work like that, but other (greener, less harmful or more practical) solvents work as well. Need to check some lab books..... Concentration, MW of polymer, temperature and ratio of solvent to non-solvent are all important.
Hi LORENZO,
I did polymerization of CL (caprolactone) many times. I recommend you to add some calcium hydride stirrer for over night and then go for vacuum distillation. For PCL , If you follow this route you will get PCL with polydispersity index 1.2 or 1.3 so you don't need to purify. If you are still confuse whether it is polymerization from your polyol or water or something else. Just measure GPC and check whether you get single peak or multiple peaks. If it is single peak then there is no problem. Keep remember degree of polymerization of CL with different initiator is different so if you have some other reagent than polyols then you will get different chain length of PCL. Good luck. Let me know if you need further help.
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