Since CSA is a strong electrolyte you will be able to make CSA doped PANI by electropolymerization of Aniline in CSA solution. Use a Pt substrate. Then you will be able to dissolve it in DMF and process it, if you need.

P.S. You should not use higher potentials.

Yes, the APS itself and its decomposition product (SO42-) can dope the PANI. In terms of the competition, the organic acids should dominate the doping process due to their much larger size.

But if you want to obtain an absolutely pure organic acid doped PANI, I suggest you to use the electro-chemical polymerization method.

Yes, APS can participate as a dopnt but as a minor dopant. The organic acid dopant will dominate due to its high concentration as compared to the produced sulfate anilons so the produced polymer contain botrh dopants.

Thank you guys for your answers...I would really appreciate if you could provide some papers that mention this phenomenon. To be honest, I couldn't find any paper directly mentioning this effect.

There is a typical paper reported by Manohar.

http://g.zhubajie.com/urllink.php?id=1286482500tq57u2fhmhhvq5

Hi I agree with you, sulfate ions at the same time dope the polymer. In my experiment though I washed the film obtained with HCl to achieve uniform doping. Anyway, I am still doing a little more research on this one.

Thank you Liyuan...the paper is very interesting....

Marissa, I think your method works OK when you have small molecules as dopant. Actually our goal is to dope polyaniline with polymeric dopants (such as PAA and PSSA), which I think is not possible to be done with above mentioned method.

ANI + APS --> PANI + H2SO4 + .....

this is how PANI could be doped when we used APS.

Thank you all again. Just to reconfirm your answers, I put the link of a paper that I just found, in which this phenomenon is clearly mentioned and investigated.

Palaniappan, S. (2002), Preparation of polyaniline-sulfate salt ­by emulsion and aqueous ­polymerization pathway without using ­protonic acid. Polym. Adv. Technol., 13: 54–59. doi: 10.1002/pat.154

APS does not dope Polyaniline, but it co-dopes PEDOT

@Bernhard, so you don't see any residual SO4-2/HSO4- in polyaniline powder or film (polymerised with APS) after washing?

correct, if you wash thoroughly, then you don't see; what couterion do you want to take? don't take HCl, it causes chlorinated PAni to be made

Yes. N in PAni can make coordination bonds with most of transition metals ions . But, HSAB theory suggests that N has higher affinity toward H+ than transition metals. However, during chemical polymerization Fe3+ ions can be also mechanically trapped inside of PAni aggregates. In the case of APS it is obvious that, insertion of anionic products in to the positively charged PAni back bone.

My idea is, it is better to reduce PAni to LEM and use a dilute alkaline solution to remove the anionic dopents. You can repeat this a few times.

If you need to dope a one pure dopent please use Electro deposition method as I suggested you in last year. Use your dopent as the electrolyte.

I would not follow such a route, too complicated and not well reproducible. If you polymerize aniline in para-toluene sulfonic acid / water solution, add APS dropwise, then you can get a good powder.

The FeCl3 is reduced t FeCl2 by the reaction with aniline. The dopant of the polymer is then Cl- or Cl3- ions. When a sulfonic acid is added (e.g., PSSA), the Cl ions are replaced with the sulfonate ion and the product is HCl which is evolved. The reason for doing this is that doping with the sulfonate gives higher conductivity than Cl and probably better stability to the polyaniline not having Cl ions around.

after thorough washing, you should run an elemental analysis, I assume, you will find Cl (which you will not be able to remove by even further washing), therefore you can conclude that the Cl is covalently bound.

I do not suggest to use this route.

I thoroughly agree with Dr. Wessling, Moreover, I think, that, theoretically, obtained as a result of the reaction HSO4_may interact with polymer similar to HCl and you may have covalently bonded SO4-, too. I But I haven't met such result for emeraldine

For H2SO4, according to my experience, no covalently bound sulfate can be found (i.e., when neutralizing with NH4OH and running elemental analysis of the neutral emeraldine base, no S would be found).

However, H2SO4 "doped" polyaniline is thermally not very stable. Therefore I recommend again p-toluene sulfonate, this is thermally most stable:

https://www.researchgate.net/publication/244490182_Thermal_stability_of_Polyaniline_Tosylate?ev=prf_pub

Article Thermal stability of Polyaniline Tosylate

Dear Bernhard,

Do you have any experience on polymeric acid-doped polyaniline? I wonder what the structure of e.g., PSSA-doped PANI is? is it again like the helical primary particles you suggested earlier for the doped-PANI? I would appreciate if you refer me to your papers on this topic.

Thank you.

I also have experience with PSSA-doped PAni, that one is much less ordered and not well characterized (PSSA inside and outside of PANi primary particle). I did not publish anything about PSSA-PAni structure. The basic PAni chanin form (helical) will be the same

I assume so but have no evidence for it, I think this inherent in PAni as one can deduct from some papers by Wallace et al about optically active PAni; but they never made the final conclusion from a very interesting experiment: they made optically active PAni using a chiral counterion (like D-campher sulfonic acid), then neutralized = removed the optically active counterion, only had the neutral PAni / Emeraldine base, but this was still optically active, anbd very strong! so the PAni chains must have a helical structure.

Dear Ehsan

I think the best method is in situ polymerization of aniline in presence of polymer acid to get the homogenous polymer acid doped PANI.

However I want to ask you some questions

1.how much the weight percentage of Aniline/polymer acid should be to get the highest electrical conductivity?

2. since the polymer acid doped PANI is soluble in water, how can to filter and dry it to get the powder? because I tried to filter it,but the whole PANI solution is passed through the filter.

Appreciated

Ahmad, to your questions:

1. you use an excess of acid, and the best relation (later in the dry polymer powder) is 2:1 for monomer unit:acid group

2. also the polymer acid doped PAni is NOT soluble in water, it is a dispersion, it only "looks" to your eyes as if a solution, but your eyes can only see micrometer-sized things (at best), optical microscope can see 1 µm, but the particles in dispersion are (if PSSA-doped) around 50 nm small, and for sure a dispersion, you can find a lot of publications on my RG pages

Thanks dear Bernhard

You mentioned that the best ratio is 2:1 for monomer unit : acid group .can you give the address of some reference work and also how can I calculate this ratio for aniline and polystyrene sulfonic acid?

Appreciated for your help.

Actually I don't remember in which of my many publications the 2:1 relation was documented, sorry. Maybe you can searc a little bit on my RG pages ... This relationship is correct for "doping" with toluene sulfonic acid.

For PSSH, the relationship does not apply, there is a surplus (excess) of PSSH compared to Aniline monomer units, and the conductivity is quite low.

Thanks a lot for you guides. By the way I wanted to know what cause the conductivity of polyaniline to increase or decrease ? Is it relate to ratio of N+:N in polyaniline ?

there are 2 or 3 major requirements,

a) dopant (optimally: pTs) to monomer units should be 1:2

b) polyaniline chain order (therefore: slow polymerisation)

c) post-processing (dispersion) which leads to higher order.

For this (c)), I recommend to read www.mdpi.com/2073-4360/2/4/786 (I have this article in RG as well)

Thank u so much dear Bernhard, if anything else I will ask u later

Best regards

Ahmad, regarding your question about powder preparation, you can easily precipitate your PANI dispersion in other solvents like acetone, and then dry the powder in oven (or using vacuum)

Thank you dear Ehsan.

I will try and if I got problem I will inform you

NOP , the sulfate ions never doped the polyaniline , experimentally sure

For polymerization of polyaniline the medium should be acidic..As i tried without acid and use only APS but aniline did not convert to Polyaniline...

I have a similar question too.

there are two things, oxidant and dopant. oxidant is the one that oxidises initiates the polymerisation. I haven't found anything that explains if there is any bond formation with the monomer. Second is dopant that helps increase the conductivity. I want to know that during polymerization, does the dopant form any chemical bonds with monomer chains??

Ankur Shukla there is no bond formation between APS and monomer (e.g. aniline)

The dopant form ionic "bonds" between the polymer chain and the dopant, i.e.

a) the dopant's H(+) protonates some location on the chain

b) the negative counterion sits in between the chains and compensates this charge

for further reading and an idea about the structure of polyaniline (which I believe is similar for other conductive polymers), look and read here:

Article New Insight into Organic Metal Polyaniline Morphology and Structure

Is Ammonium persulfate use as the dopant for heteroatom doping over carbon materials?

s. Suresh Balaji actually, I do not really understand your question: what carbon materials do you want to dope? and APS is a strong oxidant, not a dopant.

Thank you professor for your reply. Actually, my question is whether APS can be used as a precursor or dopant for the heteroatom doping over carbon materials such as CNT, CNF and graphene likeurea?

s. Suresh Balaji I don't think so