Synthesis and solution properties of a new ionic polymer and its behavior in aqueous two-phase polymer systems

The amine salt, N,N-diallyl-N-carboethoxymethylammonium chloride was copolymerized in dimethyl sulfoxide using ammonium persulfate or azo-bis-isobutyronitrile (AIBN) to afford the cationic polyelectrolyte (CPE) having five-membered cyclic structure on the polymeric backbone. The CPE on acidic (HCl) hydrolysis of the pendent ester groups gave the corresponding cationic acid salt (CAS) having the equivalent of chloride salt of N,N-diallylammonio ethanoic acid as monomeric unit. The CAS was converted into an anionic polyelectrolyte (APE) and polybetaine (PB) [having the monomeric unit equivalent of sodium N,N-diallylaminoethanoate and N,N-diallylammonioethanoate] by treatment with two and one equivalent of base, respectively. The solution properties of APE were investigated by potentiometric and viscometric techniques. Basicity constant of the amine functionality in APE is found to be 'apparent' and as such follow the modified Henderson-Hasselbalch equation; the protonation of the APE becomes more and more difficult as the degree of protonation (a) of the whole macromolecule increases. The composition and phase diagram of the aqueous two-phase systems of APE and poly(ethyelene glycol) (PEG) has been studied for the first time for this class of ionic polymers. The CAS and PB were found to be virtually insoluble in water. (C) 2001 Elsevier Science Ltd. All rights reserved.