Amine-reactive surface chemistry of zinc phosphate glasses

Abstract

Surface chemical studies on zinc phosphate glasses were carried out with an ammonia probe using FTIR and XPS. Low softening point zinc phosphate glasses can be co-extruded with high softening point polymers to form polymer filled blends. NH3 reacts with P-OH groups (Br⊘nsted acid sites) to form bound NH4+ and with the zinc ions (Lewis acid sites) to form coordinately bound NH3. Bulk nitridation reactions, forming various P-N bonds to >100 nm, occur concurrently. The glass surfaces were depleted in Zn compared to the batch compositions. Exposure to ambient water vapor removed Lewis acid bound ammonia; aqueous washing removed both types. Di- and tri-methyl amines also reacted with surface Br⊘nsted and Lewis acid sites. These amine reactions have the potential for binding polymer chains to the glass surface.