The ion-exchange and associated interfacial reaction mechanisms of silicate glasses are critical in elucidating their aqueous corrosion behaviors, surface modification and property changes, hence have potential impact on both science and technology. This work reports findings of the atomic and nanoscale details of the glass–water interfacial reactions revealed by applying reactive force field (ReaxFF) based molecular dynamics (MD) simulations, from which the key mechanisms of the ion exchange, as well as the kinetics of associated interfacial reactions, are elucidated. It was found that the Na⁺ and H⁺ ion exchange can happen between two oxygen ions on a single silicon oxygen tetrahedron or adjacent tetrahedra. In addition, the clustered reaction of two non-bridging oxygens mediated by an adjacent water molecule was also identified. The latter reaction might be the main mechanism of water transport after initial surface reactions that consume the non-bridging oxygen species on the surface. Water molecules thus can play two roles: as an intermediate during the proton transfer processes and as a terminator of the clustered reactions. Statistical analyses were performed to obtain reaction kinetics and the results show that silanol formation is a more favored process than the silanol re-formation within the first 3 ns of interfacial reactions. The results obtained thus shed lights on the complex ion-exchange mechanisms during glass hydration and enable more detailed understanding of the corrosion and glass–water interactions of silicate glasses.

硅酸盐玻璃的离子交换和相关的界面反应机理对于阐明其水腐蚀行为，表面改性和性能变化至关重要，因此对科学和技术都有潜在的影响。这项工作报告了通过应用基于反作用力场（ReaxFF）的分子动力学（MD）模拟揭示的玻璃水界面反应的原子和纳米级细节的发现，从中可以得出离子交换的关键机理以及氢的动力学。阐明了相关的界面反应。发现Na ⁺和H ⁺离子交换可以在单个硅氧四面体或相邻的四面体上的两个氧离子之间发生。另外，还鉴定了由相邻的水分子介导的两个非桥接氧的聚集反应。在初始表面反应消耗了表面的非桥联氧之后，后者的反应可能是水传输的主要机理。因此，水分子可以起两个作用：作为质子转移过程中的中间体和作为簇状反应的终止剂。进行统计分析以获得反应动力学，结果表明，在界面反应的前3 ns内，硅烷醇的形成比硅烷醇的重整是更有利的过程。