Influence of low-molecular-weight salts on the formation of polyelectrolyte complexes based on polycations with quaternary ammonium salt groups in the main chain and poly(sodium acrylate)

The effects of NaCl, Nal and Na2SO4 on the formation of polyelectrolyte com plex (PEC) between a polycation with N,N-dimethyl-2-hydroxypropyleneammoniu m chloride units in the main chain (PCA(5)) and poly(sodium acrylate) (NaPA ) were studied. The NaCl concentration in the polyelectrolyte solutions ran ged from 0 to 2 M. Viscometric and turbidimetric measurements were used to follow the effect of the salt concentration and of the counterion nature on the PEC formation. The influence of counterions was different depending on both the radius of the hydrated ion and its valence. At the same concentra tion of the low-molecular-weight salt, the following order of the PEC separ ation in dependence on the counterion was evidenced: R-sep(SO42-) < R-sep(I -) < R-sep(Cl-). The critical concentration of NaCl for this system was est ablished. (C) 2001 Elsevier Science Ltd. All rights reserved.