Topo-chemical characterisation of dissolution processes of phosphate glasses

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Phosphate glasses can dissolve in aqueous solutions, which is a great advantage for some applications (e.g. controlled release), but a pronounced drawback for others (e.g. laser glasses or optical filters). Tailoring and controlling glass dissolution has so far, based on our current knowledge, been achieved by phenomenological approaches only. An improved understanding of the dissolution mechanism may pave the way towards the structural design of optimised glasses of tailored solubility or improved chemical stability. Here, 31P solution nuclear magnetic resonance (NMR) spectroscopy will be used to characterise phosphate fragments formed during dissolution, either using in situ or ex situ approaches. This will give insight into network dissolution and fragmentation as well as hydrolysis occurring in solution. Modified topology-based calculations, which account for field strength, packing and medium-range (sterical) effects, have been used successfully to describe the mechanical properties of phosphate glasses. These structure-based models will be extended here to allow for precise quantitative prediction and optimisation of the dissolution process. The aim of this study is the combination of experimental investigations with topological and structure-chemical models. This will give insight into the mechanisms of phosphate glass dissolution and, subsequently, allow for the development of new strategies for controlling and tailoring glass solubility, through optimised glass compositions on the one hand and control of chemical parameters during dissolution on the other hand.