Adsorption and Ionic Crosslinking of Polyelectrolytes

Abstract

Materials formed by polymers containing ionic or ionizable groups in their chemical repeating units (polyelectrolytes) have been of interest in the area of biomaterials over the past two decades. Presently, two largely polyelectrolytic compositions are utilized as dental cements or as restorative materials for hard oral tissues. These two types of dental biomaterials are the zinc polycarboxylate cements (1) and the glass ionomer cements and restoratives (2). Dental impression materials, known as alginates (3), represent an additional example, as they are partly based on an ionizable polysaccharide, alginic acid. Polyelectrolyte-based materials have been tested for other biomedical applications, such as the formulation of cardiovascular elastomers (4), dialysis membranes (5), drug delivery systems (6), or surgical adhesives (7). As a consequence of past and current research activity, it is possible that polyelectrolytes will find application in some of these areas in the near future. It is interesting to consider that biological tissues themselves contain considerable amounts of polyelectrolytic material. This fact alone does not, of course, guarantee that synthetic polyelectrolytes should lead to the successful development of nearly ideal biomaterials from a mechanical, chemical or biocompatibility standpoint. Nonetheless, a strong interest in these materials, and their potential advantages can be justified on the basis of some of their characteristic features, depending on the specific application involved. Some of these characteristic features, and their relevance in the formulation of biomaterials, have been described below.