Copper is one of the most used catalysts in Atom Transfer Radical Polymerization (ATRP); however, it has to be removed afterwards in order to obtain pure and non-toxic polymers.
Removal of the copper catalyst from atom transfer radical polymerization mixtures by chemical reduction with zinc powder-Read this article
The general method is to pass the polymer tsolution hrough an alumina column and then recover the polymer either by precipitation or solvent evaporation method. If the polymer is hydrolyzable use neutral alumina column. It is preferable to wet the column with the solvent first and then pass polymer solution through the column. Pressure may need to be applied to force the polymer solution through depending on the molecular weight of the polymer followed by final washing with solvent alone. Some polymer might be lost by this method.
Passing through alumina column (may need to do this twice) is the best practical method. If you are dealing with small amount, water soluble polymer, buy Cuprisorb, or amy aquarium water treatment kit that removes metal. Awesome stuff, you know.
Depends on your repeat unit. Passing through alumina works only well for non-polar polymers. For polar polymers, there's only little enthalpic gain for the copper to stick to the column. Quantitative removal from polar polymers is therefore rarely achieved. Complexation works, but only if you can remove the complexes efficiently afterwards, which can be a severe problem. I would look for some resin-bound Cu complexation agent. I also played around with ion exchange columns, which worked ok in some cases.
I agree what jimmy propose: Cuprisorb.
However, what is the copper source? Copper(I) I suppose, so, be sure that all copper(I) is oxidazed into Cu(II).
If the polymer is extractable in an organic solvant, you could use EDTA in water to remove your Cu.
What is the amount of copper? to decrease the amount, see: DOI: 10.1021/ja048096a
Thank you all for your suggestions. I will try them and see which one is the more convenient for me. As for the copper amount, I begin the reaction with 20 mg of CuBr (I). In the end it all goes blue, so I suppose it all converted to Cu(II).
Its usually trace of copper in ATRP but difficult to remove from hydrophilic polymers. What is the polymer you made by ATRP. If it is hydrophilic it would be difficult to remove the complex in that case you can go for dialysis in water. This removes the copper complex and unreacted monomers completely but its a slow process. If the polymer is hydrophobic or mildly hydrophilic you can use the alumina column. There are literature reports using alumina column to remove copper complex even for PEG based polymers.
People are often too impatient when they finished ATRP. If I don't like what I am seeing from the copper color, I generously bubble filtered air, and then the standard alumina or cuprisorb, and I have never needed to do this, but dialysis may work, but you lose some polymers too and that's not an elegant method. If you absolutely need to free all the copper from hydrophilic polymer, I guess you can test the solution by adding sodium sulfide(aq).
Jimmy's procedure will work in the majority of cases (maybe not for negatively charged polymers). Dialysis will also not work for negatively charged polymers, though. If you want to quantify how low you've gotten in Cu content, use atomic absorption spectroscopy (AAS).
How about using copper-free ATRP if you can't get rid of your copper?
I recommend you, obtained polymer passed over alumina to remove the catalyst, washed and dried overnight in vacuum.
Copper gives a complexing reaction with ammonia to form a strong blue compound. Extracting with ammonia (if there are no problem for the polymer) can give you also an indication when the extraction is finished as the complex is coloured also at low copper concentrations.
You can try Aq Ammonia or Di ethyl amine wash, I think it is a general method of removal.
Or extract with aq. ammonia untill colorless aq.layer is obtained (it will be deep blue color if copper is present)
Please try to extract with aqueous ammonia you might be complete the work up easily by the convenient complex formation and watchable good work up .
I agree with all previous posts. But, have you ever tried to use cation exchange resin?
If your polymer is not water soluble, then just wash it out with water. You can monitor the progress by UV-vis of the used wash water. You've got a lot of good ideas here. I hope that you find one works well.
All the above answers should work. But the key is the type of copper species you have at the end of your rxn. Complexed copper? If so, which ligands ar bounded to copper? We have worked out this rxns just by adding to the final mixture, prior to any workup, silica gel. Our ligands interact with SiO2 (softer than alumina...) and just stirring and filtering will make it. Later on polymer is precipitated with methanol... free of copper uo to 1 ppm (but you have to play a while with amounts of SiO2 and so on...). Hope it works.
Thank you all for your time! I have tried some of the aboved suggested methods, and I have to admit that alumina works best.
For hydrophilic polymers, try this method: Cu Elimination from Cu-Coordinating Macromolecules, MF Ebbesen, D Itskalov, M Baier, L Hartmann, ACS Macro Letters 6 (4), 399-403)