Preparation of MMMs
After successful synthesis of MOF materials, the MOF NPs and pMOF MSs
were mixed in PSF matrixes to fabricate MMMs. The MOF particles and PSF
powders were first dispersed and blended in CHCl3 for
obtaining homogeneous inks, followed by casting and complete drying for
membrane formation. The SEM images of the pristine PSF membrane,
MOF-NP/PSF MMM (NH2-UiO-66 NPs and PSF), and pMOF-MS/PSF
MMM (polymer-embedded NH2-UiO-66 MSs and PSF) were
captured for observing the microstructures (Figure 4 and Figure S5,S6).
Compared with the smooth PSF membrane, the MOF-NP/PSF and pMOF-MS/PSF
MMMs displayed rough cross section due to the incorporation of MOF
fillers. It could be found that the serious aggregation of fillers and
the distinct interfacial defect between two phases appeared in the
MOF-NP/PSF MMM (Figure 4a,b), which would serve as non-selective
pathways for molecular transports and then reduce selectivity. The
filler aggregation and the interfacial defect of the pMOF-MS/PSF MMM
were alleviated substantially, derived from the identical
characteristics of the embedded PSF with the matrix of MMMs as well as
the micrometer-sized structures of the pMOF MSs (Figure 4c,d). The
broken pMOF MSs and the well cohesive interface suggested that the
interfacial binding force was even stronger than that of the intrinsic
MSs themselves (Figure 4d). The tight interfacial combination confirmed
the excellent affinity of the polymeric matrixes to the pMOF MSs.