Mechanism of adhesion between 4-META resin and alloys based on Bolger's acid-base interaction.

The water durability at adhesion interfaces between 4-META resin and Au-In or Au-Si alloys was investigated by the peeling test and by surface analysis using X-ray photoelectron spectroscopy (XPS) as well as theoretical consideration based on Bolger's acid-base theory. XPS spectra demonstrated that several-nm thick layers of In2O3 and SiO2 were formed on the Au-In and Au-Si alloys. The water durability of the Au-In alloys increased with increases in In content. The Au-Si alloy and quartz glass specimens showed a total absence of water durability. Bolger's theory suggested that the interaction of 4-MET with In2O3 was considered to be ionic and stable in the presence of water while that of 4-MET with SiO2 was due to hydrogen bonds, which can easily be dissociated in the presence of water. These findings suggest that Bolger's theory is useful for evaluating chemical interactions between an adhesive monomer and oxides on a precious metal alloy.