Effects of Surfactant Modification on Microporous Membranes

Membranes formed from metal-organic frameworks (MOFs) are receiving much attention in research. Current methods of synthesis include direct or secondary growth of MOFs on ceramic substrates such as alumina, while mixed-matrix membranes (MMMs) where MOF fillers and a polymer matrix are combined together are also an intense topic of research. Although membranes have many important industrial applications, such MOF membranes often have stress-induced cracks and defects resulting from differences in thermal expansion coefficients of the MOF material and the substrate, or from capillary pressure experienced during drying, leading to lowered gas permeation results. Therefore, this project aims to investigate the use of commonly found surfactants to improve the structural integrity of MOF membranes, and to analyze their gas permeation and separation performances.The three-year project proposed here describes the plan to progressively complete the construction of the gas separation/permeation setup already started by our group, to systematically synthesize and analyzeMOF membranes after modification by surfactants, and to quantify differences in gas permeation andseparation properties. Target MOFs chosen for this project include prototypical structures such as MOF-5,ZIF-8, and MIL-53(Al), but also include novel MOFs of note, including NH2-MIL-53(Al) and UiO-66. Preliminary testing of surfactants on MOF-5 have been performed using 7 types of surfactants including CTAB, PEG-200 and -400, P-123, F-127, Span 80, and AM6 (the last two often used in conjunction). This project proposal details the goals and agenda for beginning with the existing incomplete gas separation rig and preliminary surfactant modification results to the final vision of an experimental platform capable of modifying and synthesizing MOF membranes, characterizing its structure, and testing for gas separation. This platform will then enable a systematic investigation of the effects of surfactant modification on microporous MOF membranes.