Which acid to use to convert the ionizable groups containing -COONa and -SO3Na to -COOH and -SO3H groups in sodium polystyrenesulfonate chain so that I can bring the pH of aqueous solution of sodium polystyrenesulfonate below or around 1. If I use HCl then, in the reaction meadium NaCl will be formed and I need another effort to separate NaCl from the polymer solution. Finally, I wish to get the pure polystyrenesulfonic acid as powder form through freeze drying without containing NaCl salt. Please suggest and I shall be thankful.
ِAs Professor Bojidarka B. Ivanova suggested correctly, it is HCl. You will add hydrochloric acid & these 2 reactions occur:
polymer---COO-Na+ + HCl(aq) → Polymer---COOH + NaCl(aq)
and polymer---SO3-Na+ + HCl(aq) → Polymer---SO3H + NaCl(aq)
The outcome is not worrying since the side product "aqueous salt solution" can be separated easily to the last trace. Most probably, the -COOH & the SO3H will be in the para positions with respect to the main chain. Worth trying & I wish you success.
@Prof. Nizar Matar. Thank you for the comment with beautiful explanation. Would you suggest some technique to separate the salt NaCl after the reaction is done! Thank you. By the way, in my case, one single polymer chain contains one -COONa as end group and -SO3Na in all the repeating units. And yes, they are in para position. Thank you again.
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