Preparation of zinc sodium polyphosphates glasses from coacervates precursors. Characterisation of the obtained glasses, and their applications

Abstract

A soft chemistry route is described to obtain glasses in the P 2 O 5 -Na 2 O-ZnO-H 2 O. It is based on the addition of zinc salts to coacervates prepared from sodium polyphosphate. The processing of these coacervates leads to polyphosphate glasses with the same properties as those of glasses prepared in the classical way. So far, little work has been implemented in this system using 'coacervate route'. However, it makes an attractive method for coating and joining processes on the industrial scale. As the anion associated to zinc may take part in the adhesion mechanism, coacervate formation has been studied using zinc chloride, nitrate and sulphate as starting materials. The physical properties of the glasses obtained by this method are reported and potential applications of zinc and silver coacervate are described. To cite this article: G. Willot et al., C. R. Chimie 5 (2002) 899-906 © 2002 Académie des sciences / Éditions scientifiques et médicales Elsevier SAS glass / polyphosphate / coacervate / coating / sealingRésumé -Nous décrivons une nouvelle méthode permettant d'obtenir par voie douce des verres dans le système P 2 O 5 -Na 2 O-ZnO-H 2 O. Elle est basée sur la formation de coacervats de polyphosphates obtenus par l'action de sels de zinc sur des solutions concentrées de polyphosphate de sodium. Par chauffage, on obtient, à des températures de l'ordre de 400 °C, des phases vitreuses ayant les mêmes propriétés que les verres obtenus par une méthode classique. Cependant, compte tenu des propriétés des coacervats, cette méthode permet de développer des procédés de collage ou de revêtements applicables en milieu industriel. Comme les anions associés aux sels de zinc utilisés peuvent intervenir dans les mécanismes d'adhésion, nous avons étudié plus en détail les mécanismes de formation des coacervats à partir des chlorure, nitrate et sulfate de zinc. Nous donnons les propriétés physiques des verres obtenus par ce procédé, ainsi que les potentialités de verres obtenus à la fois à partir de coacervats de zinc et d'argent.

Comprehensive Study of the Chelation and Coacervation of Alkaline Earth Metals in the Presence of Sodium Polyphosphate Solution

“…The chelation of divalent cations by polyphosphate chains caused the pH of the solution to decrease, an effect previously reported by several researchers. 21,31,32 We showed that the pK a value of hydrogen atoms at the end of the chains also decreases during chelation. This pH effect can be explained, therefore, by the dissociation of hydrogen atoms at the chain ends.…”

Preparation and structural characterization of sodium polyphosphate coacervate as a precursor for optical materials

“…In this paper, our methodology was based on the work proposed by Umegaki et al [1]. These authors suggested that after the addition of methanol to sodium polyphosphate solution a liquidliquid phase separation occurs, considering the coacervate obtained as the denser phase [12,14]. In this paper, we studied the synthesis of sodium coacervates and how the addition of different amounts of methanol (4.25…”

“…The addition of solvents, such as alcohols or acetone to aqueous sodium polyphosphate, in order to prepare coacervates is known through literature. However, in some cases, the addition of divalent cations occurs, as Zn 2þ , Co þ , Ni 2þ etc., for example, [5,12,14]. The novelty in this work is that the coacervation occurs by adding methanol to the polyphosphate without needing the presence of another cation.…”

“…Willots et al studied the coacervation process as an alternative route for glasses preparation. He highlights the use of ethanol as a solvent for the phase separation process [12]. Silva et al prepared a great amount of transparent amorphous materials using the coacervation process of sodium polyphosphate or Graham Salt containing Ni 2þ and Co 2þ applying methanol to reduce the dielectric constant of the mixture [5,13].…”

Calcium polyphosphate precipitation – A strategy to tune the chain length of the glass and control the subsequent release of vancomycin

“…Several studies have previously confirmed the osteoconductivity, biocompatibility and degradable nature of CPP [5e13] and it has been studied for use in cartilage and bone repair, as well as for angiogenesis [9,14e18]. In the literature, CPP is most commonly fabricated in the furnace [6,19]. Unfortunately, only a few studies have examined the chain length of this "melt-derived" CPP as a function of furnace conditions and the results have proven inconclusive [20e22].…”