Li Shichun, Limbach René, Longley Louis, Shirzadi Amir A, Walmsley John C, Johnstone Duncan N, Midgley Paul A, Wondraczek Lothar, Bennett Thomas D
Department of Materials Science and Metallurgy , University of Cambridge , Charles Babbage Road , Cambridge CB3 0FS , U.K.
Institute of Chemical Materials , China Academy of Engineering Physics , Mianyang 621900 , P. R. China.
J Am Chem Soc. 2019 Jan 16;141(2):1027-1034. doi: 10.1021/jacs.8b11357. Epub 2019 Jan 8.
Melt quenched metal-organic framework (MOF) glasses define a new category of glass, distinct from metallic, organic, and inorganic glasses, owing to the dominant role of metal-ligand coordination bonding. The mechanical properties of glasses in general are important given their application in protective coatings and display technologies, though little is known about MOF glasses in this respect. The experimental elucidation of key properties such as their scratch resistance has been limited by the lack of processing methodologies capable of producing bulk glass samples. Here, nanoindentation was used to investigate the Young's modulus and hardness of four melt-quenched glasses formed from zeolitic imidazolate frameworks (ZIF): aZIF-4, aZIF-62, aZIF-76, and aZIF-76-mbIm. The creep resistance of the melt-quenched glasses was studied via strain-rate jump (SRJ) tests and through constant load and hold (CLH) indentation creep experiments. Values for the strain-rate sensitivity were found to be close to those for other glassy polymers and Se-rich GeSe chalcogenide glasses. Vacuum hot-pressing of aZIF-62 resulted in an inhomogeneous bulk sample containing the glass and amorphous non-melt-quenched aZIF-62. Remelting and annealing, however, resulted in the fabrication of a transparent, bubble-free bulk specimen, which allowed the first scratch testing experiments to be performed on an MOF glass.
熔融淬火金属有机框架（MOF）玻璃定义了一种新型玻璃，与金属玻璃、有机玻璃和无机玻璃不同，这是由于金属 - 配体配位键的主导作用。鉴于玻璃在防护涂层和显示技术中的应用，其一般力学性能很重要，不过在这方面对MOF玻璃了解甚少。由于缺乏能够制备块状玻璃样品的加工方法，对其诸如耐刮性等关键性能的实验阐释受到了限制。在此，使用纳米压痕法研究了由沸石咪唑酯框架（ZIF）形成的四种熔融淬火玻璃的杨氏模量和硬度：aZIF - 4、aZIF - 62、aZIF - 76和aZIF - 76 - mbIm。通过应变率跳跃（SRJ）试验以及恒载和保持（CLH）压痕蠕变实验研究了熔融淬火玻璃的抗蠕变性。发现应变率敏感性值与其他玻璃态聚合物和富硒GeSe硫属化物玻璃的值相近。对aZIF - 62进行真空热压得到了一个包含玻璃和非熔融淬火的非晶态aZIF - 62的不均匀块状样品。然而，重熔和退火导致制备出了一个透明、无气泡的块状样品，这使得首次能够在MOF玻璃上进行划痕测试实验。
