钠钙磷酸盐玻璃在不同水介质中的非线性溶解机理与pH的关系
Non-linear dissolution mechanisms of sodium calcium phosphate glasses as a function of pH in various aqueous media
摘要：
用于生物可吸收植入物的磷酸盐玻璃显示出随组成而显著变化的溶解速率，然而目前它们的溶解机制尚不清楚。基于这一系统的研究，我们提出了新的见解，这些机制。两个阶段的溶解观察，与时间的依赖性最初抛物线和后来的线性，和一个两阶段的模型来描述这种行为。玻璃中较低的Ca浓度和溶解介质中较低的pH值加速了溶解。提出了一种新的溶解机制，涉及的初始阶段，在扩散控制形成的转换层发生。一旦转化层稳定，层溶解反应就变得限速。在这种机制下，转变时间对转化层的性质和溶液条件敏感。这些结果揭示了P $_{2}$ O $_{5}$ -CaO-Na $_{2}$ O玻璃溶解对溶液pH的依赖性，并提供了对溶解机制的新见解，特别是关于两个溶解阶段之间的过渡。
英文摘要：
Phosphate glasses for bioresorbable implants display dissolution rates that vary significantly with composition, however currently their mechanisms of dissolution are not well understood. Based on this systematic study we present new insights into these mechanisms. Two-stage dissolution was observed, with time dependence initially parabolic and later linear, and a two-stage model was developed to describe this behaviour. Dissolution was accelerated by lower Ca concentration in the glass, and lower pH in the dissolution medium. A new dissolution mechanism is proposed, involving an initial stage where diffusion-controlled formation of a conversion layer occurs. Once the conversion layer is stabilised, layer dissolution reactions become rate-limiting. Under this mechanism the transition time is sensitive to the nature of the conversion layer and solution conditions. These results reveal the dependence of P$_{2}$O$_{5}$-CaO-Na$_{2}$O glass dissolution on solution pH, and provide new insight into the dissolution mechanisms, particularly regarding the transition between the two dissolution stages.
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