The Dissolution Of Soluble Phosphate Glasses

"The solubility of phosphate glasses in aqueous solutions can be tailored through compositional control to obtain a wide range of ion release rates required for a variety of applications. The principal objective of this dissertation is to advance the understanding of the dissolution behavior of phosphate glasses in aqueous environments. Two families of glasses, sodium-iron phosphate (NFP) glasses and sodium-calcium phosphate (NCP) glasses, were evaluated. The dissolution behavior depends on the phosphate anions that constitute the glass structure and the associated metal (Me) cations. The phosphate glass structure, defined by the distribution and average size of phosphate anions and depending on the O/P and Me/P ratios, was determined by high-pressure liquid chromatography and Raman spectroscopy; Mössbauer spectrometry provided information about the coordination environment of iron. This structural information is used to explain the compositional dependence of the thermal properties and crystallization tendency of NFP glasses and melts, and the aqueous corrosion behavior of NFP and NCP glasses. Phosphate glass dissolution data are fit to different kinetic models which describe the glass dissolution mechanisms. Information about the glass composition and structure is used to predict changes in the pH of leachate solutions, and a model based on the Gibbs free energy of hydration used to explain the compositional dependence of the glass dissolution rates"--Abstract, page iv.

Inorganic glasses are successfully used in the biomedical field, in particular degradable glasses have found applications in tissue engineering, bone regeneration and tooth remineralisation. Silicate glasses are the most commonly used ones but phosphate and borate glasses are attracting more and more interest owing to their special properties, differing from those of silicate bio-glasses. Phosphate and borate glasses thus open up potential routes for new therapeutic applications. This book focuses on these emerging materials. Bridging the phosphate and borate glasses communities, this book provides a fundamental treatment of atomic structure and physicochemical properties before highlighting their current and potential future applications. Phosphate and borate glasses not only feature a broader range of glass formation than silicate glasses. Their ability to completely dissolve in water with the solubility varying over orders of magnitude with compositional changes, makes them exciting materials for delivering therapeutic agents into the human body. Biomaterials scientists working in glasses, hard tissue engineering and regenerative medicine will find this a must-have book to own, alongside their more traditional silicate glass tomes.

This handbook provides comprehensive treatment of the current state of glass science from the leading experts in the field. Opening with an enlightening contribution on the history of glass, the volume is then divided into eight parts. The first part covers fundamental properties, from the current understanding of the thermodynamics of the amorphous state, kinetics, and linear and nonlinear optical properties through colors, photosensitivity, and chemical durability. The second part provides dedicated chapters on each individual glass type, covering traditional systems like silicates and other oxide systems, as well as novel hybrid amorphous materials and spin glasses. The third part features detailed descriptions of modern characterization techniques for understanding this complex state of matter. The fourth part covers modeling, from first-principles calculations through molecular dynamics simulations, and statistical modeling. The fifth part presents a range of laboratory and industrial glass processing methods. The remaining parts cover a wide and representative range of applications areas from optics and photonics through environment, energy, architecture, and sensing. Written by the leading international experts in the field, the Springer Handbook of Glass represents an invaluable resource for graduate students through academic and industry researchers working in photonics, optoelectronics, materials science, energy, architecture, and more.

"Borate glasses have been developed for biomedical applications such as scaffolds for soft tissue and bone repair. The dissolution processes of borate glasses in phosphate-containing aqueous solutions were studied by [mu]-Raman spectroscopy which provided information about the types and concentrations of borate species released into the solution as a function of time and characterized the formation of calcium phosphate reaction products on the glass surface. Boric acid molecules (H3BO3) and borate anions (B(OH)4−) can be detected in solution and their relative concentrations depend on the solution pH. Static and dynamic single-pass flow-through experiments were employed to study the dissolution kinetics of a borate bioactive glass 13-93B3 in water, simulated body fluid (SBF), and other solutions. As the glasses react, B-, Ca-, Na-, K-, Mg-, and P-species were released from the glass and a magnesium-containing amorphous calcium phosphate (ACP) or hydroxyapatite (HAP) layer formed on the surface of the glass. The formation of crystalline hydroxyapatite was favored with faster flow rates, longer reaction times, and increased phosphate concentration in solution. Under static conditions, the dissolution rates are initially described by a reaction-controlled model (linear kinetics), but after the glass is ~25-30% reacted, a diffusion-controlled model (parabolic kinetics) better describes the dissolution rates. The change in reaction mechanism is attributed to the diffusion of species from the glass through the ACP layer. The activation energy for the reaction-controlled process is 41.1±0.6 kJ/mol, whereas the activation energy for the diffusion process is 32.3±0.1 kJ/mol. For the SPFT experiments, glasses dissolved faster under faster flow rates and smaller glass volumes. The ion release rate was calculated and found to range from 1.7x10−5 g/m2/s for slow flow rates to 1.1x10−3 g/m2/s for lower glass volumes."--Abstract, page iv.

This handbook provides comprehensive treatment of the current state of glass science from the leading experts in the field. Opening with an enlightening contribution on the history of glass, the volume is then divided into eight parts. The first part covers fundamental properties, from the current understanding of the thermodynamics of the amorphous state, kinetics, and linear and nonlinear optical properties through colors, photosensitivity, and chemical durability. The second part provides dedicated chapters on each individual glass type, covering traditional systems like silicates and other oxide systems, as well as novel hybrid amorphous materials and spin glasses. The third part features detailed descriptions of modern characterization techniques for understanding this complex state of matter. The fourth part covers modeling, from first-principles calculations through molecular dynamics simulations, and statistical modeling. The fifth part presents a range of laboratory and industrial glass processing methods. The remaining parts cover a wide and representative range of applications areas from optics and photonics through environment, energy, architecture, and sensing. Written by the leading international experts in the field, the Springer Handbook of Glass represents an invaluable resource for graduate students through academic and industry researchers working in photonics, optoelectronics, materials science, energy, architecture, and more.

The field of bioactive glasses has been expanding continuously over recent years. This book aims to give the material's scientist an up-to-date reference and guide for education, studies and research.