The role of aluminium and silicon in the setting chemistry of glass ionomer cements.

摘要: A model of the setting chemistry glass-ionomer cements (GICs) is proposed based on 27Al and 29Si solid state nuclear magnetic resonance spectroscopy data three GICs. All precursor glasses are found to contain aluminium species viz.: four, five six-coordinate environments as well four-bridging silicate tetrahedra. Upon cement formation, Al3+ ions in glass leached out from surface layer glass. On entering matrix, these adopt six-coordination crosslink polymer chains part reaction. The remaining four-coordinate distributed between two species: one inert core particles; a second, less concentrated, particles, modified by curing reactions. There some evidence for residual six coordinate final systems. In case tetrahedra, reactions result decrease number atoms second coordination sphere, with subsequent recondensation network