Soluble polyelectrolyte complexes composed of poly(ethylene oxide)-block-poly(sodium methacrylate) and poly(methacryloyloxyethyl trimethylammonium chloride)

Complexation between poly(methacryloyloxyethyl trimethylammonium chloride), PMOTAC, and poly(ethylene oxide)-block-poly(sodium methacrylate), PEO-block-PMANa with MANa blocks with two different molecular weights has been investigated by light scattering, LS, viscosimetry and conductivity measurements. Owing to the PEO blocks the polyelectrolyte complexes are water-soluble particles. Effects of the ratio of the oppositely charged monomer units, the ionic strength of the solution, and solution pH have been studied. With the 1:1 mixing ratio stable polyelectrolyte complexes, PECs, with spherical shape were formed. When either the cationic or anionic component was in excess, charged non-stoichiometric complexes were formed. The complexes were stable also in solutions with comparatively high ionic strength, though stronger secondary aggregation was observed. By changing the solution pH the degree of dissociation of PEO-block-PMANa could be adjusted. In the vicinity of the pKa,average of PMAA, a minimum in the particle size and a maximum in the solution conductivity were observed. In solutions with lower pH, a typical self-complexation of PEO-block-PMAA was detected. Also, unexpected interactions between PMOTAC and the self-complexes of PEO-block-PMAA were observed.