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Prediction of the Glass Transition Temperatures of Zeolitic Imidazolate Glasses through Topological Constraint Theory

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journal contribution
posted on 28.11.2018, 00:00 by Yongjian Yang, Collin J. Wilkinson, Kuo-Hao Lee, Karan Doss, Thomas D. Bennett, Yun Kyung Shin, Adri C. T. van Duin, John C. Mauro
A topological constraint model is developed to predict the compositional scaling of glass transition temperature (Tg) in a metal–organic framework glass, agZIF-62 [Zn­(Im2–xbImx)]. A hierarchy of bond constraints is established using a combination of experimental results and molecular dynamic simulations with ReaxFF. The model can explain the topological origin of Tg as a function of the benzimidazolate concentration with an error of 3.5 K. The model is further extended to account for the effect of 5-methylbenzimidazolate, enabling calculation of a ternary diagram of Tg with a mixture of three organic ligands in an as-yet unsynthesized, hypothetical framework. We show that topological constraint theory is an effective tool for understanding the properties of metal–organic framework glasses.