Glass Ionomer Technology

The enhanced performance resin-modified glass-ionomers are high in resin, and as a result appear to have somewhat compromised adhesion. Their bioactivity appears very good. Considerable further work is required to know whether or not these materials represent a significant advance in glass-ionomer technology and restorative dentistry. 

Hornsby, P. R. (1980). Dimensional stability of glass-ionomer cements. Journal of Chemical Technology and Biotechnology, 30, 595-601. 

The two types of tooth-colored material, namely, the composite resin and the glass-ionomer cement, are described, together with their current variations. Composite resins are bonded with specific bonding agents, and this technology has advanced rapidly over the last 10 years or so. Surface pretreatment is critical for the success of these systems and the current state of the understanding of this aspect of the subject is described. 

Hill, R. G. Wilson, A. D. (1988a). Some structural aspects of glasses used in ionomer cements. Glass Technology, 29, 150-88. 

Amine-Linked and Complexed Ionomers. Oiganic bases, notably diamines, can be substituted for metal ions to give ionomers which have similar solid-state properties to those neutralized with metal ions but differ in the area of melt viscosity. A general overview of the various properties has been published (45,46). Diamines may also be combined with metal cations to give transparent, tough products (47—50). This technology is used commercially in glass interlayers. 

Several organic sealants such as epoxy resins, butyl rubber or silicones prove to be more or less permeable and the tiny amount of solvent in the cell is rapidly lost. Suitable organic sealing materials for this technology turn out to be thermoplastic materials, like polyethylene/carboxylate copolymers. So far, Surlyn 1702 ionomer from Dupont has been the main substance used to optimize cell performance and build module prototypes. However, the softening point of Surlyn is rather low (65° C) and at elevated temperatures (> 70°C), serious solvent loss is observed because the bond between Surlyn and TCO-coated glass is substantially weakened [7]. 

We would like to make one last but important comment. With aU the new membranes, the current MEA technology that uses a Nation ionomer as an electrode binder should be optimized for new electrolyte and DMFC systems. Novel MEA processes for new electrolytes will reduce the interfacial resistance of membranes and electrodes. Although conventional membranes, such as Nafion, have an elastomeric property and low glass transition temperature, methanol-impermeable membranes have some degree of rigidity. Thus, the adhesion process has to be optimized so that those efforts of membrane development can maximize MEA performance. 

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