Although nucleation is considered the first step in the crystallization of glass materials, the structure and properties of the nuclei are not understood well. Influence of nucleation on the structure and dynamics of celecoxib glass was evaluated in this study. The nuclei for Form III were induced by annealing the glass at freezing temperature, and their impact on the relaxation behavior was investigated using thermal analysis and broadband dielectric spectroscopy to find accelerated α relaxation and suppressed β relaxation. In addition, observed after nucleation was a decrease in cooperativity of the molecular motion, presumably because of the appearance of void spaces in the glass structure. During long-term isothermal crystallization studies, crystal growth to Form III was accelerated in the presence of the nuclei, whereas this effect was less remarkable when a different crystal form dominated the crystallization behavior. These observations should provide more detailed insights into the nucleation mechanism and impact of nucleation on molecular dynamics including physical stability of pharmaceutical glasses. In addition, discussed is the remarkable acceleration of the crystallization rate of the celecoxib glass just below its T_g, which could be understood by diffusionless crystal growth.

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成核对塞来昔布玻璃的弛豫、分子协同性和物理稳定性的影响

尽管成核被认为是玻璃材料结晶的第一步，但人们对晶核的结构和性质仍知之甚少。本研究评估了成核对塞来昔布玻璃结构和动力学的影响。通过在冷冻温度下对玻璃进行退火来诱导形成 III 型的核，并使用热分析和宽带介电谱研究了它们对弛豫行为的影响，以发现加速的 α 弛豫和抑制的 β 弛豫。此外，在成核后观察到分子运动的协同性降低，这可能是由于玻璃结构中出现了空隙空间。在长期等温结晶研究中，在晶核存在的情况下，晶体向 III 型的生长加速，而当不同的晶型主导结晶行为时，这种效应就不那么显着。这些观察结果应为成核机制以及成核对分子动力学（包括药用玻璃的物理稳定性）的影响提供更详细的见解。此外，还讨论了塞来昔布玻璃在其T _g以下时结晶速率的显着加速，这可以通过无扩散晶体生长来理解。