As the reaction is exothermic, the temperature is increasing rapidly. Is it fine or does it affect the conductivity of polyaniline? Whether emeraldine salt will be formed or not?
It is not fine, letting the teperature increase will lead to a totally different PAni structure; running the synthesis under cooling at low temperature conditions compared to uncontrolled increase of temperature for instance leads to a totally different reaction enthalpy delta H, by orders of magnitude different.
Plus, when running at high and increasing temperature, the resulting PAni is totally undispersible, while when running at low temperature with max 1 degree increase, the material will be dispersible.
You can achieve that by cooling your reactant solution to 2 or 3 degrees above zero, do the same with the APS solution, keep the reactor in an ice bath, and add the APS solution so slowly that the temperature increase rate is practically the same as the cooling rate; allow the reactant liquid to increase temperature by max 1 degree.
You can use ice packs to control the temperature during the polymerization process, also add APS drop wise in aniline solution. Set your reaction in a plastic tray full of ice packs and put this assembly on a magnetic stirrer which also shows temperature. As the temperature reaches to 2-3 degrees Celsius you can start adding the APS solution drop wise. Stirr the solution for next 3-4 hours to allow polymerization and then leave the solution in undisturbed position for a night. Filter the solution and wash it with 1M HCl and distill water. Then dry it in vacuum for 24 h and you will get a conductive emeraldine salt form of PANI.
I always recommend not to use HCl as counterion for PAni, but PTSA. Generally, Amitap, you are right, but it is necessary to *control* the temperature, not just blindly cool and add APS dropwise (how many drops per minute?). One should make sure that the temperature during reaction is stable at 2 - 3 degrees above Zero, by proper monitoring the reaction temperature and the APS addition rate.
Even if I am adding APS drop wise, the temperature is rising randomly and after few minutes (10min approx.) the temperature is coming down. One thing I want to mention is that the rate of APS addition is 1 drop per 10 second, even I tried 1 drop per 30 second; but all in vein ..The temperature of ice bath is -2 degree Celsius and ambient temperature is 35 degree Celsius..
Check your molar concentration of Aps solution with HCl and keep this solution in different ice bath on magnetic stirrer continuously for 40-45 minutes and switch off the heat completely. Then add this solution to the aniline one which is also kept in another ice bath tub on magnetic stirrer for 40-45 minutes. Keep in note the temp of both the solutions should be maintained between 0-5 °C . After both the solutions are added , keep on magnetic stirrer for 1.5 hour-2 hour. Than keep the solution over night for 12-16 hours. Hope this helps !
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