Ionomers

The molecular structure and composition of ionomers lead to a complex superposition of properties of organic chains and of polyelectrolytes. The potential use of this class of polymers in applications such as surfactants, ion selective membranes in electrochemical processes, coatings, fuel cells and batteries has sparked a vast amount of research.

Polymers have achieved an enviable position as the class of materials having the highest volume of production, exceeding that of both metals and ceramics. The meteoric rise in the production and utilization of polymers has been due to advances in polymer synthesis which allow the creation of specific and well-defined molecular structures, to new knowledge concerning the relationships between polymer structure and properties, and to an improved understanding of how processing can be used as a tool to develop morphological features which result in desired properties. Polymers have truly become 'engineered materials' in every sense of the term. Polymer scientists and engineers are forever seeking to modify and improve the properties of synthetic polymeric systems for use in specific applications. Towards this end they have often looked to nature for advice on how to design molecules for specific needs. An excellent illustration of this is the use of noncovalent bonding (ionic, hydrogen, and van der Waals) in lipids, proteins, and nucleic acids, where these noncovalent bonds, acting both intra and intermolecularly, precisely control the structure and thus the function of the entire system. The utilization of ionic bonding, in particular in man-made polymers has attracted widespread interest in recent years, since ionic interactions exert a similar strong influence on the structure and properties of these synthetic systems.

Ionomers, that is polymers containing a low concentration of charged units along the chain, have been the subject of increasing interest during the past twenty years. The presence of ionic groups in the poly mer changes some of its properties dramatically. Increases in the modu lus and the viscosity of several orders of magnitude have been observed, and changes in the glass transition of hundreds of degrees are possible. In addition, diffusion coefficients can be modified drastically. These changes are due primarily to the presence of reversible ionic cross links in these materials. Because of the low dielectric constant of most organic polymers, the ions or ionic dipoles tend to aggregate ; this aggregation process, however, is limited, because the ionic groups are covalently bonded to the organic chain. Host of the fundamental research done on these materials has been devoted to a determination of the extent of association, the structure of the aggregates, the limi ting factors, and the correlations between molecular and supermolecular structure and the resul ting properties.

This text comprehensively reviews bonding to enamel, dentin and cementum, and analyses relevent adhesion mechanisms. Emphasis is placed on the characterization of material interfaces with dental tissues in situ.

Introduction -- History -- Manufacture -- Properties -- Applications -- Fuel cells and batteries -- Commercial membrane types -- Economic aspects -- Experimental methods -- Heat sealing and repair -- Handling, storage and installation -- Toxicology, safety, and disposal -- Appendices.

This concise handbook covers all aspects of glass-ionomer cements, from the development of these materials in the early 1970s through to the current state of the art. Their physical, chemical, biological, and clinical properties are described as well as how their formulation and usage have evolved over time, giving rise to newer subcategories of the parent materials. Detailed coverage is provided on the clinical use of glass-ionomer cements in restorative and pediatric dentistry and in widely taught and practiced newer approaches, including atraumatic restorative treatment and minimal intervention dentistry. The authors are internationally acclaimed experts who present information in an easy-to-follow format that will appeal to readers. With the renewed worldwide quest for substitute materials for the more traditional amalgam, glass-ionomer cements have the potential for further development and may play a significant role in future trends.​

The status of glass-ionomers as a restorative material continues to improve along with their reputation for longevity. They have now been shown to be moderately bioactive, so they have a very important role to play in remineralizing tooth structure and helping to heal carious lesions. This comprehensive clinical guide to their uses in operative den