Best living profi in polyaniline prep and solubility : https://www.researchgate.net/profile/Bernhard_Wessling2/

haha, Andrei, thanks for the promotion :-)

Neha Patni, Polyaniline is absolutely insoluble, you can prepare colloidal dispersions, and on my RG pages, you can find a lot of publications about this. Maybe as a first overview, you look here:

https://www.researchgate.net/publication/253651172_Conductive_Polymers_as_Organic_Nanometals

Chapter Conductive Polymers as Organic Nanometals

thanks for the guidance Dr. Andrei and Dr. Bernhard

Hi Neha! Thanks for upvote and following!

One remark to Dr. Wessling message - question about solubility is pending. I analyse slowly arguments and not all is so clear. Once you will have polyaniline in hands, please report me again.

Andrei, what arguments are not clear to you? Can I help you?

In my paper(s), I have given many experimental and in addition theoretical thermodynamical arguments, I can help you to understand if you want.

I tried dissolving , rather making dispersion in DMSO , I got comparatively good solubility, yet not proper.

Hi to all!

Bernhard, sorry for delay with answer, I have lost your message.

I have question to you, but answer can be interesting for Neha.

Polypyrrole is really very same to metals - it is very good free radical scavenger and can accept up to 4 radicals per unit. Reduction potential is same to phenols. It is also known that metals dissolution is accompanied with electron lost - infact we have solutions of cations. Free metals can not be dissolved - because of metallic bonding. Electrons are accepted by protons (usually) or solvated with building of blue colored solutions in ammonia and rare in water (blue is color of solvated electrons! - but not colorless solvated cations of sodium). To have "real" solution of individual chains of polypyrrole, its molecules should lost electrons - with building of polycations. From this point of view is question - are such solutions known? Can polypyrrole be dissolved in strong acids (with oxidant, or hydrogen emission)? What is range for tested solvents? CF3CH2OH, (CF3)2CFOH, CH3COOH, HCOOH, CH3SO3H, CF3SO3H are especially interesting.

I wrote polypyrrole by mistake instead of polyaniline , but fortunately, they are very close and even reductions potentials.

Now once again I have check an idea , and really,there is a way to produce a soluble polyaniline, we just need to choose right organic acid - see attachement.

I think this is due to the blocking of the dimerization of cation-radicals (which means crosslinking and insolubility) - my colleagues had this problem on the example of usual anilines. Under certain conditions, one can be obtain 4,4' - diaminobiphenyls through the cation-radicals.

http://web.itu.edu.tr/~bicak/Papers/74.pdf

http://www.scientificbulletin.upb.ro/rev_docs_arhiva/full4049.pdf

to Neha Patni: yes, DMSO is a good solvent for dispersing Polyaniline, what you get from it is a dispersion, not a solution, also "solubility" is not the correct term, but should be "dispersibility". Please read my related papers.

Depending on polymerisation (and post-polymerisation processes = rinsing, drying) conditions, dispersibility can be super, so so ok, or bad in the same dispersion medium like DMSO. I can run polymerisation lots with 100% dispersibility = no particle bigger than 100 nm, average particle size 10 - 20 nm), and at the same time, I can run a polymerisation with 0% dispersibility - no colour, only black particles in the same dispersion medium under same dispersion conditions.

I can not go into any detail why this is the case and how to run it the best way (confidentiality), but when looking in my patents, you should be able to find at least some hints.

Andrei, (I was already surprised about "polypyrrole", because that one is so badly dispersible, I never achieved 100% dispersibility). Ok, you are talking about polyaniline.

The old paper "Soluble Polyaniline.pdf" is not reliable at all. The authors simply say "it is soluble", but do not show any experimental evidence for it. In my papers about solubility / dispersibility, I have clearly defined what has to be shown, tested and proven if one would like to express a statement like "this polyaniline is soluble".

More or less the same needs to be commented for the other paper (the "scientificbulletin" link you provided): there is not one single experiment / analysis showing what the authors measured to determine the "solubility percentage" they reported (like "solubility 1.7%" in their table - what does the 1.7% tell us? what are these 1.7% like?)

I tell you: if they would have measured the particle size, they would find something like 10 ... 100 nm particle size, a dispersion.

Although the authors cited my solubility / dispersibility related papers, and cited the requirements for solubility, they did not really consider what I wrote and simply said "soluble" ... no, PAni with DBSA is not soluble, it forms - under certain conditions - nice dispersions, what's wrong with that?

(part 2 to follow)

(part 2)

- metal solutions: in my key solution paper, I have cited and described one metal solution, Na in liquid NH3; if you refer to metal cation solutions, you don't have a metal solution, but you start with a metal and oxidize it to the cation, then you have a cation solution, not a metal solution! that's not the same! In case of Na in NH3, it is not solvated electrons, as far as I am aware of; this seems to be a real metal solution in NH3

- you correctly ask whether it is possible to have isolated polyaniline chains which are already charged, and the charges are compensated by counterions: I have explained in my papers why this is not possible

- even in strong acids, such a isolated individual chains have not been described nor shown: the acids - the acids will simply protonate the chains and compensate the polarized particles (I have shown that polyaniline nano-particles are anisotropic which is one of the reasons for strong agglomeration, and for fibril formation).

- some excess of strong acids "simply" builds a cloud around particles thereby rendering the particles including their clouds isotropically charged, like PSSA also does which makes them water dispersible.

Any further questions or comments? (part 3 to follow)

(part 3)

More or less same comment to the "ionic liquids" paper: how do the authors determine PAni there is soluble and not in the stage of dispersion?

This is a very critical question, a key question because solutions and dispersions are completely different systems, different like day and night, plus and minus, 0° and 180° and 360°, equilibrium and non-equilibrium!

Dear Ms. Patny,

polyaniline (PANI) can be dissolved in a

mixture of water (pH=4) / N-methylpyrrolidone (NMP) of 9:1 (v/v)

at a PANI concentration of e.g. 0.001M.

Best regards,

Martin Müller

sorry, Mr. Müller,

as I have outlined above, PAni can not be dissolved at all. I have shown this and explained in several publications, here is a review chapter out of some handbook:

https://www.researchgate.net/publication/253651172_Conductive_Polymers_as_Organic_Nanometals

I assume you will have looked with your eyes and saw some clear transparent but strongly coloured liquid, I assume it was blue (that would be the EB form, not conductive, less interesting for studies because one wants to study the conductive form, green in colour, much less easy to become dispersed).

But your eyes can not distinguish between a true solution and a dispersion which contains dispersed particles having (far!) less than 100 nm small particles. Some much more sophisticated studies need to be done to determine whether or not you have a true solution.

I did these studies and concluded: PAni is principally insoluble. (you may want to read the chapter I cited above)

Chapter Conductive Polymers as Organic Nanometals