ENVIRONMENT-SENSITIVE PROPERTIES OF POLYMETHACRYLIC ACID-GRAFTED POLYETHYLENE MEMBRANES

The theories of electrolytic dissociation and complexation are applied to predict the configurations of polymethacrylic acid grafted onto polyethylene membranes. It is established that the principal factor affecting the configuration of the grafted chains are the electrostatic forces acting among the dissociated carboxyl groups. The configuration of the grafted chains depends entirely on the state of the carboxyl groups. The porosity parameter is found to vary inversely with the net charge in the chains. This parameter is determined for different water-alcohol mixtures, different pH values and three model complex-forming agents, Cu2+, Ca2+ and Cr3+. It is found that the concentration interval of the complex-forming agents at which the change in configuration takes place depends on various factors such as pH, stability constants of metal complexes with hydroxyl and carboxyl ions, as well as the valency of the complex-forming agents. The theories of electrolytic dissociation and complexation satisfactorily predict the behavior of the polymethacrylic acid-grafted membranes. The concept explains well the results obtained by some previous authors as well as ours.