Perspectives on the Influence of Crystal Size and Morphology on the Properties of Porous Framework Materials

Miniaturization is a key aspect of materials science. Owing to the increase in quality experimental and computational tools available to researchers, it has become clear that the crystal size and morphology of porous framework materials, including metal-organic frameworks and covalent organic frameworks, play a vital role in defining the physicochemical behaviour of these materials. However, given the multiscale and multidisciplinary challenges associated with establishing how crystal size and morphology affect the structure and behaviour of a material–from local to global structural modifications and from static to dynamic effects–a comprehensive mechanistic understanding of size and morphology effects is missing. Herein, we provide our perspective on the current state-of-the-art of this topic, drawn from various complementary disciplines. From a fundamental point of view, we discuss how controlling the crystal size and morphology can alter the mechanical and adsorption properties of porous framework materials and how this can impact phase stability. Special attention is also given to the quest to develop new computational tools capable of modelling these multiscale effects. From a more applied point of view, given the recent progress in this research field, we highlight the importance of crystal size and morphology control in drug delivery. Moreover, we provide an outlook on how to advance each discussed field by size and morphology control, which would open new design opportunities for functional porous framework materials.

Methane and Carbon Dioxide Hydrate Formation and Dissociation in Presence of a Pure Quartz Porous Framework Impregnated with CuSn12 Metallic Powder: An Experimental Report

Hydrate formation and dissociation processes were carried out in the presence of a pure quartz porous medium impregnated with a metallic powder made with a CuSn12 alloy. Experiments were firstly made in the absence of that powder; then, different concentrations were added to the porous medium: 4.23 wt.%, 18.01 wt.%, and 30.66 wt.%. Then, the hydrate dissociation values were compared with those present in the literature. The porous medium was found to act as an inhibitor in the presence of carbon dioxide, while it did not alter methane hydrate, whose formation proceeded similarly to the ideal trend. The addition of CuSn12 promoted the process significantly. In particular, in concentrations of up to 18.01 wt.%, CO2 hydrate formed at milder conditions until it moved below the ideal equilibrium curve. For methane, the addition of 30.66 wt.% of powder significantly reduced the pressure required to form hydrate, but in every case, dissociation values remained below the ideal equilibrium curve.