Fluoride ion release from two methacrylate polymer systems

The release of fluoride ions from two room-temperature polymerising systems containing sodium and potassium fluoride, respectively, has been studied. The polymer systems comprised poly(ethyl methacrylate) powder (PEM), with tetrahydrofurfuryl methacrylate (THFM), and n-butyl methacrylate (nBM), respectively. The water uptake of these systems was drastically increased by the presence of fluorides, the increase being much higher with the PEM/THFM system. In both cases, uptake was a monotonic function of the molarity of the fluoride added. The uptake process was in general non-Fickian. However, for all systems, the fluoride release process was Fickian, and diffusion coefficients could be calculated. The amount of fluoride released, and the diffusion coefficients obtained, appeared unrelated to the extent of water uptake of the parent polymers.