When only a small amount of APS is added to a solution of aniline in (acidic) water, then the PAni (emeraldine salt) formed is present in form of extremely small nanoparticles. therefore you get the impression this may be a solution, but in fact it is a dispersion. The more APS you add, the more the small primary Emaldine Salt particles will be formed and finally flocculate, then you get a PAni powder which you can filter.

You can find a lot of publications in my RG page, and patents I had filed you can find from my website http://www.bernhard-wessling.com/pani, go to "milestones & highlights" under "History".

Bernhard Wessling

I'm Synthesizing Polyaniline (PANI) (emeraldine Salt). by reacting ammonium persulphate with aniline hydrochloride and at temp.

0-5 °C . but it ends up with emeraldine salt with black color instead of green or deep green why??? , what is this means ? And how could i change the color of the salt to green???

The colour of the salt will be green, but because in powder form, it is densely aggregated / agglomerated, it appears black. As soon as you would disperse it (or for a test, you can smear it onto glass and look through a microscope), itz will be green.

Bernhard Wessling

thank you prof.

now for washing the formed salt, i use Distilled water and acetone

but the color of the water and the acetone is brown and didn't change to colorless is this ok? and how much of water and acetone i need to wash i use about 100 ml of each or should i use HCl 37% ?

using acetone during washing is a very bad idea: acetone undergoes Aldol condensation on the surface of the PAni particles; that's the major reason for the brown colour.

Instead of HCl as dopant for PAni, you should use para-toluene sulfonic acid (instead of starting polymerisation with aniline hydrochloride, you should use aniline in pTs / water), and washing starts with dilute pTs / water, then distilled water.

Bernhard Wessling

thank you prof.

but how the acetone undergoes Aldol Reaction on the surface ?? is this because the medium is acidic due to the HCl results form the reaction of the persulphate and the anilinehydrochloride? or another reason and does the acetone react with the PAni ?

and what about the conductivity if the salt which i prepared the reaction happened on the surface will affect on the conductivity??

the surface of the freshly prepared PAni (and anyway PAni in general, also if not fresh) is highly acidic; the reaction has nothing to do with the reactants formerly used for running the polymerisation;

the acetone does not react with PAni, but the aldol reaction product becomes adsorbed on the PAni particle surface and deteriorates the PAni properties.