Figure 2. Surface morphology of PDMS (a, b) and 15% Ni-ZIF-8
MMM (c, d), cross section image of 15% Ni-ZIF-8 MMM (e, f).
In addition to surface morphologies, the dispersion of Ni-ZIF-8
nanoparticles within the polymer matrix was further verified using the
EDX analysis shown in Figure S8. The continuous grey and green colors
representing the Si and O, respectively, reflecting Si–O backbone of
the polymer matrix. The Si and O colors have filled the mapping, which
confirmed that all Ni-ZIF-8 nanoparticles are wrapped with the PDMS
layer. The blue, red, and yellow colors are representing the Zn, N, and
Ni, respectively. The good distribution of these three colors confirmed
the excellent dispersion of Ni-ZIF-8 nanoparticles within the polymer
matrix, which might be beneficial to create the relatively continuous
pathways for molecular diffusion. In order to improve the separation
performance and defect-free membrane synthesis, homogeneous dispersion
of the filler, and excellent compatibility between organic and inorganic
phases must be created12.
The tests of TGA, EDX, SEM, and EDX revealed that the Ni-ZIF-8 has
excellent interaction with PDMS chains, and could activate the Van der
Waals forces and hydrogen bonding between Ni-ZIF-8 and polymer phases.
Moreover, the addition of Ni-ZIF-8 in the PDMS did not alter the
crystallinity and chemical structure of PDMS, as shown by XRD and FTIR
analysis.