I will explain you ALL the mistakes:

1) First of all, the more bulky substitute you are tacking the less reactive is the ionic monomer. So, initially you made not so good choice for the ionic monomer with benzyl group. To be more correct, when you will have an increase in the system's viscosity due to polymerization, for your monomer it will be more hard to be attached.

2) I will say "absolutely no" to the just nitrogen atmosphere. You need to remove oxygen from your system. Otherwise, O2 is a good inhibitor. So, you can do it in a normal Schlenk flask with three (!) freeze-pump-thaw cycles. Small secrets: for DMF and H2O as a solvents (that are practically not evaporating under vacuum at rt) and for your ionic monomer (not evaporating at all) you do not need to freeze. It is possible to make the vacuum in your flask for 5-7 minutes and just degas the solution.

3) I prefer to make polymerization under vacuum (after three freeze-pump-thaw cycles or simple degasing). In this case you are not making mistakes. Otherwise, you need after degasing to fill the flask with oxygen free nitrogen or argon. This is a tricky thing as you need firstly to make vacuum in your tubes connecting the flask and the N2 line. Usually this is a normal mistake of students. They are degasing the solution and not thinking that there is an oxygen in the rubber tubes. Another secret: if you will do the polymerization under vacuum you should properly choose the volume of your Schlenk flask (it must be filled with solution up to 2/3 of its volume) .

4) Reactivity of the ionic monomer vs anion:

Cl >> BF4 > TFSI

The more reactive is the monomer with the Cl anion !!! Sometimes ionic monomers with bulky TFSI are not even capable of polymerization. So, use the chloride monomer.

5)   Solvents. Please see the raw of the solvents in terms of the highest possible molecular weight of obtained polymer (monomer is with the chloride anion):

in bulk (no solvent used, only for liquid monomers) >> ionic liquid ~ H2O > DMF > ethanol

So, for your monomer I will definitely recommend  H2O as a solvent !! The amount of the solvent is 2:1 - 3:1 by wt. with respect of the monomer's load ( 2 wt. parts of the solvents per 1 wt. part of the monomer). 2:1 ratio is the best, but sometimes you can get the cross-linked polymer, so I will say start with 2:1 and then you will see.

6) Initiator.

The less amount of initiator you are using the higher Mm you will get and simultaneously the lower yield of the polymer. The optimum amount for ionic monomers is usually in the range of 0.5-1.0 wt.%. 2 wt. % was toooooo much.

I will recommend 1 wt. % in respect to the monomer mass.

If you will prefer to use DMF --> then you need AIBN, if H2O --> use ACVA. In case of AIBN (independently of the company) the crystallization of initiator from methanol is OBLIGATORY and then drying under high vacuum at rt for at least 2 h. In the case of ACVA - the one from Sigma-Aldrich you do not need to crystallize.

Conclusions: use H2O (2:1 ratio by wt), 1 wt. % of ACVA, 70oC, 8-9 h, under vacuum or nitrogen

use DMF (2:1 ratio by wt), 1 wt. % of AIBN (recrystallized), 60oC, 8-9 h, under vacuum or nitrogen

Best regards,

Alexander

Hi

It is possible to polymerize this monomer , witg Maghnite-H or Montmorillonite,in bulk at RT.

Pr M.Belbachir

Thank you for your feedback,

I will have a look into the suggested initiator. Could you eleborate a bit about the procedure or supply a literature reference, Mohamed?

Regarding Michels question:

I tried to polymerize vinylbenzyl imidazolium chloride (quaternization of vinylbenzyl chlorid with methyl imidazole). I have a nmr and I will post it tomorrow. Thank you.

I am mostly interested to understand the process of this paticular radical polymerization in more detail, so papers and book recommendations are very welcomed.

Best regards

Judith

Hi, you can see this paper. It help you possoibly.

Thermoresponsive poly(ionic liquid): Controllable RAFT synthesis, thermoresponse, and application in dispersion RAFT polymerization

DOI: 10.1002/pola.27929

http://onlinelibrary.wiley.com/wol1/doi/10.1002/pola.27929/full

Most probably you still have quite a lot of inhibitor in your monomer and that's why it is not polymerising properly. Try also using a more aggressive radical starter.

Dear Michel,

I followed the follwing procedure:

4,9 g VBMIM Cl in DMF(80 wt%) mixed then 2 wt% AIBN (recristallized) dissolved in DMF added and cooked with a cooler under Nitrogen @ 80°C 16 hrs overnight --> precipitation not sucessfull

Repeat:

4,9 g VBMIM Cl in DMF (80 wt%) mixed then 1 wt% AIBN (recristallized) dissolved in DMF added and cooked with a cooler under Nitrogen @ 80°C 16 hrs overnight --> precipitation not sucessfull

4,9 g VBMIM Cl in DMF (80 wt%) mixed then 1 wt% BPO dissolved in DMF added and cooked with a cooler @ 80°C 16 hrs overnight --> precipitation not sucessfull

4,9 g VBMIM Cl in Chlorofom (80 wt%) mixed then 1 wt% AIBN dissolved in Chloroform added and cooked with a cooler @ 80°C 16 hrs overnight --> precipitation not sucessfull

4,9 g VBMIM Cl in DMF (70 wt%) mixed then 1 wt% AIBN (recristallized) dissolved in DMF added and cooked with a cooler under Nitrogen @ 80°C 72 hrs --> geled product not dissolveable in water/MeOH/EtOH/EtAc/MeCN/DMF/Acetone/Tolene

0,5 g  VBMIM Tf2N in DMF (70 wt%) mixed then 1 wt% AIBN (recristallized) dissolved in DMF added and cooked with a cooler under Nitrogen @ 80°C 72 hrs --> precipitation but very mucilaginous --> not film forming

0,5 g VBMIM Tf2N in DMF (70 wt%) mixed then 1 wt% AIBN (recristallized) dissolved in DMF added, Freeze thaw cycles and Polymerization in an anionic line under Argon @ 80°C 16hrs overnight --> no precipitation

Do you want the NMR of all the starting products? for the geled I tried solid state NMR but no success. The sucess of the polymerization I checked by looking at the IR in the process and by precipitation.

Dear Boyan,

I calculated the amount of Inhibitor and the amount of initiator was definitly exeeding the inhibitor amount.

I had a look into transfer constants of solvents and DMF is less qualified compared to Chloroform. But I also found that the polymerization of Methyl styrene works best, in bulk (without solvent) and lower amount of Initiator. So maybe that was the problem? Because the Molecular weight that I achieved was too low for precipitation? Do you think the stabilization of the benzyl radical was negativly contributing to the result?

I believe the 1-vinyl-3-benzylimidazolium is meant and it is also clear how it was synthesized. The question is rather the purification and if the monomer has not at least partially already polymerized and how much of the stabilizer is stuck into it. Chloroform should indeed be better than DMF and molecular weight will have an effect on solubility, how about making an MS before we jump to conclusions?

@Michael: yes, you are right, I missed this one...so it's the 1-(4-vinyl-benzil)-3-methylimidazolium chloride....

 I will explain you ALL the mistakes:

1) First of all, the more bulky substitute you are tacking the less reactive is the ionic monomer. So, initially you made not so good choice for the ionic monomer with benzyl group. To be more correct, when you will have an increase in the system's viscosity due to polymerization, for your monomer it will be more hard to be attached.

2) I will say "absolutely no" to the just nitrogen atmosphere. You need to remove oxygen from your system. Otherwise, O2 is a good inhibitor. So, you can do it in a normal Schlenk flask with three (!) freeze-pump-thaw cycles. Small secrets: for DMF and H2O as a solvents (that are practically not evaporating under vacuum at rt) and for your ionic monomer (not evaporating at all) you do not need to freeze. It is possible to make the vacuum in your flask for 5-7 minutes and just degas the solution.

3) I prefer to make polymerization under vacuum (after three freeze-pump-thaw cycles or simple degasing). In this case you are not making mistakes. Otherwise, you need after degasing to fill the flask with oxygen free nitrogen or argon. This is a tricky thing as you need firstly to make vacuum in your tubes connecting the flask and the N2 line. Usually this is a normal mistake of students. They are degasing the solution and not thinking that there is an oxygen in the rubber tubes. Another secret: if you will do the polymerization under vacuum you should properly choose the volume of your Schlenk flask (it must be filled with solution up to 2/3 of its volume) .

4) Reactivity of the ionic monomer vs anion:

Cl >> BF4 > TFSI

The more reactive is the monomer with the Cl anion !!! Sometimes ionic monomers with bulky TFSI are not even capable of polymerization. So, use the chloride monomer.

5)   Solvents. Please see the raw of the solvents in terms of the highest possible molecular weight of obtained polymer (monomer is with the chloride anion):

in bulk (no solvent used, only for liquid monomers) >> ionic liquid ~ H2O > DMF > ethanol

So, for your monomer I will definitely recommend  H2O as a solvent !! The amount of the solvent is 2:1 - 3:1 by wt. with respect of the monomer's load ( 2 wt. parts of the solvents per 1 wt. part of the monomer). 2:1 ratio is the best, but sometimes you can get the cross-linked polymer, so I will say start with 2:1 and then you will see.

6) Initiator.

The less amount of initiator you are using the higher Mm you will get and simultaneously the lower yield of the polymer. The optimum amount for ionic monomers is usually in the range of 0.5-1.0 wt.%. 2 wt. % was toooooo much.

I will recommend 1 wt. % in respect to the monomer mass.

If you will prefer to use DMF --> then you need AIBN, if H2O --> use ACVA. In case of AIBN (independently of the company) the crystallization of initiator from methanol is OBLIGATORY and then drying under high vacuum at rt for at least 2 h. In the case of ACVA - the one from Sigma-Aldrich you do not need to crystallize.

Conclusions: use H2O (2:1 ratio by wt), 1 wt. % of ACVA, 70oC, 8-9 h, under vacuum or nitrogen

use DMF (2:1 ratio by wt), 1 wt. % of AIBN (recrystallized), 60oC, 8-9 h, under vacuum or nitrogen

Best regards,

Alexander

For details you can see:

dx.doi.org/10.1021/ma2014518

dx.doi.org/10.1016/j.electacta.2011.06.041

and an old one:

dx.doi.org/10.1002/pat.795

Dear Michael,

At the beginning I was thinking that the question is asked from Boyan, whom I know personally. That is why I was writing the so detailed answer. Then I realized that the question was from PhD student, but decided not to correct the text.

Of course, I was writing the procedure and the "tricky" things of polymerization keeping in mind that the purity of monomer causes no doubts!

Mm-m-m-m-mm, and I could not understand your sarcasm about "having been present during synthesis". The person is asking the concrete questions, I am trying to give the exact answers plus explanations of the possible mistakes.

Cheers,

Alexander

An interesting alternative is redox polymerization. For this purpose you must solve half of your monomer in water together with 1 weight% of potassiumperoxodisulfate or ammoniumperoxodisulfate and the other half also in water together with 1 weight% of ascorbic adic. Then you can pour both halves together and polymerization takes place at room temperature.

A complete different strategy would be to polymerize first the chloromethyl styrene (vinyl benzylchloride) optionally in presence of comonomers like styrene in a conventional manner and to make afterwards the reaction with the alkylimidazole.

Dear Scientist,

thank you very much for all the valubale contributions, espacially the detailed reply of Mr. Shaplov,

Please find attached some H-NMR.

I tried the following monomer procedure:

VB-Cl + 1-methylImidazole (without solvent) first combined at 0°C, then slow heat up to 60°C and stirring overnight.

The next day evaporation of solvents and inhibitor in a high vacuum pump (10-7 mbar) @ 60°C

or extraction with Diethylether --> removal of Diethylether by Rotary evaporator.

To dry out residual solvents zeolithes with 3 Angström used

I once run VB-Cl over a column and the tried to quaternize but it polymerized before the quaternization.

Monomers were kept in a deep freezer @-18 °C

I will have a read on the suggested papers.

Thank you very much for the contributions.

Best regards

Judith

I forgot to add: regarding the remark of AIBN, I did recrystalize it.

First top - 6 th bottom:

• First NMR VBMIM BF4 after polymerization
• 2nd VBMIM Tf2N after polymerization --> was gelly
• 3rd VB-Cl after Column
• 4th VBMIM Cl after polymerization
• 5th VBMIM Cl before polymerization
• 6th VB-Cl fresh from the bottle (sigma aldrich)

[names appear in an mouse over effect]

No it is not a mixture:

http://www.sigmaaldrich.com/catalog/product/aldrich/436887?lang=de®ion=DE&gclid=Cj0KEQiA4qSzBRCq1-iLhZ6Vsc0BEiQA1qt-zlEGNUh1mNWAXEuO-ycY5vLOzux1GGOkB9Nqei-VzYgaApyf8P8HAQ

inhibitor: 500 ppm tert-butylcatechol 

Dear Michael,

solvent for NMR was DMSO-d6, due to extraction efforts (getting rid of 10% of high boiling residues) there coud be acetone or  cyclohexane/MeOH. I did TGA-IR coupling to investigate residual solvents and they only leave around 180°C - so too high to avoid polymerization (I mean even acetone). Therefore I did not see another way than vacuum distillation to get rid of impurities after extraction (1-Methylimidazole is soluble in too many solvents) but I don't know if I got everthing out.

I don't know if it would have made sense to use a capped column for purification. I read also something about using a column and a salt e. g. NaCl in the mobile phase to shield the IL from attaching to the stationary phase?

Kind regards

Judith