Optimization of the wetting-drying characteristics of hydrophobic metal organic frameworks via crystallite size: The role of hydrogen bonding between intruded and bulk liquid

Effect of Crystallite Size on the Flexibility and Negative Compressibility of Hydrophobic Metal–Organic Frameworks

“…However, the opposite trend is observed: P int grows with increasing crystallite size, with a much greater dependence for crystallites of less than 100 nm. 28,29 In addition, the third sample, macroZIF-8, extends this trend of crystallite size versus flexibility (Figure 2), which parallels the trend of crystallite size versus P int already reported.…”

“…As we have shown in a recent article, P int can be tuned by changing the crystallite size of ZIF-8, which affects the area/volume ratio of crystallites. In combination with the results presented here, we conclude that crystallite size, through its effect on the P int and on flexibility, affects the variation of the lattice parameter and thus can be used to tune the negative compressibility of ZIF-8.…”

“…The slab sample was used for the most stable intruded state at 20 and 25 MPa, representative of the different P int of nano1and nano2ZIF-8 crystallites due to the large surface volume ratio of the former (see our recent article 28 ). We computed the free energy of the filling of a ZIF-8 cavity positioned in the inner region of the slab (Figure 3), allowing us to minimize possible "surface effects".…”

“…However, the size of the crystallites considered experimentally (approximately 35, 80, and 270 nm for nano1-, nano2-, and macroZIF-8 respectively) are beyond the scope of atomistic simulations. Therefore, a different approach was taken, in which two different computational samples were considered: the first consists of a slab immersed in water, which has been used successfully in previous works; − the second is a triperiodic simulation box obtained by duplicating the unit cell in each direction . We started our investigation exploring two aspects via the slab sample: (i) whether intruded (potentially metastable) states existed at the experimental P int of nano1- and nano2ZIF-8, and (ii) whether the characteristics of the intruded water were different at the different crystallite sizes.…”

Bimetallic Zeolitic Imidazole Frameworks for Improved Stability and Performance of Intrusion–Extrusion Energy Applications

“…The three samples are composed of dodecahedral crystals with euhedral morphology and a particle size of ∼500 nm for ZIF-67 and ZIF-8, and ∼200 nm for the hybrid ZIF. These differences in crystal size do not have an impact on the intrusion-extrusion performance as long as the crystal size is above ∼100 nm as was demonstrated in our recent study . Textural characterization of the three materials was also carried out by means of N 2 adsorption at 77 K (Figure S1 and Table S1, Supporting Information).…”