Accessing a Forbidden Disordered State of a Zeolitic Imidazolate Framework with Higher Stiffness and Toughness through Irradiation
Accessing a Forbidden Disordered State of a Zeolitic Imidazolate Framework with Higher Stiffness and Toughness through Irradiation
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DOI：
10.1021/acs.chemmater.2c01949
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发表时间：
2022-09
影响因子：
8.6
通讯作者：
T. Du;S. S. Sørensen-S.;Qi Zhou;M. Bauchy;M. Smedskjaer
中科院分区：
文献类型：
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作者：
T. Du;S. S. Sørensen-S.;Qi Zhou;M. Bauchy;M. Smedskjaer
具有纳米孔隙率的金属有机骨架(MOF)在催化、减震、离子传输、气体吸附和分离等方面具有潜在的应用前景。最近，MOF的无序状态也引起了人们的极大关注，因为一些MOF晶体可以熔化并猝灭成大块玻璃，就像首次在沸石咪唑骨架(ZIF)中发现的那样。MOF─中另一种到目前为止仍未被探索的─无序的潜在途径是辐照，例如，众所周知，硅酸盐矿物在辐照后会重排成无序状态。在这里，我们用反应分子动力学模拟研究了ZIF-4晶体和玻璃在辐照下的结构无序。我们的结果表明，这两个相会聚成一种新的“禁忌”无序态，这种无序态不能通过任何热路径到达。辐照后结构的演变使我们能够建立结构无序和力学性能之间的关系，以解释为什么辐照后的ZIF-4状态比母体ZIF-4晶体和玻璃都更坚硬和坚韧。
Metal–organic frameworks (MOFs) with nanoscale porosity have numerous potential applications, for example, within catalysis, shock absorption, ion transportation, gas sorption, and separation. Recently, the disordered state of MOFs has also attracted significant attention, since some MOF crystals can melt and be quenched into bulk glasses, as first discovered for zeolitic imidazolate frameworks (ZIFs, a subset of MOFs). Another potential route to disorder in MOFs─that so far remains unexplored─is irradiation, e.g., silicate minerals are well-known to rearrange into a disordered state upon irradiation. Here, we investigate the structural disordering of both ZIF-4 crystals and glasses under irradiation using reactive molecular dynamics simulations. Our results show that the two phases converge toward a new “forbidden” disordered state that is not accessible through any thermal path. The evolution of the structure upon irradiation allows us to establish a relationship between structural disorder and mechanical properties to explain why the irradiated ZIF-4 state is both stiffer and tougher than that of both the parent ZIF-4 crystal and glass.