Limites de solubilité des polyacrylamides partiellement hydrolysés en présence d'ions divalents

The limits of solubility of hydrolyzed polyacrylamide in aqueous solution containing divalent cations is studied by turbidimetry. The stability is very poor in the presence of Ca++ and Ba++ and is better with Mg++ and Mn++. Conductivity and density measurements show that Ca++ and Ba++ are trapped without dehydration in intra‐and intermolecular bridges between two carboxylic groups of the polymer. Light scattering and viscosity studies allowed to propose a model according to which for polymer concentrations, Cp, lower than concentration of chain overlapping Cp* these cations induce intramolecular coil‐globule transition, and for Cp > Cp*, there are aggregates of globules by intermolecular bridges.