Mobility of the imidazolate linkers in neat and confined ZIFs probed by 2H NMR

Abstract

Significant work is being devoted to the reduction of global energy consumption associated with industrial separations, with increasing attention being focused on membrane technology. In particular, MMMs containing ZIFs are an attractive alternative to conventional thermal separation processes. However, the interaction between the ZIF fillers and polymer matrix remains unclear. We believe that the separation performance of such membranes is highly interplay-dependent, and that proper selection of materials and rational modification of the fabrication procedure will enhance membrane performance. The overarching goal of this research is to understand the polymer confining effects on the motion of imidazolate linker in polymer confined ZIF fillers. The initial work used solid-state NMR to study imidazolate linker motions in ZIF crystals. The second objective directly studied the polymer confinement effects on linker motion in neat and confined ZIF crystals through 2H solid echo line shape analysis and T1 relaxation time analysis. The third objective focused on the experimental demonstration of different transport properties of ZIF crystals in neat and confined environments.