3.2. Reaction between TMC and UiO-66(Zr)-NH2
When UiO-66(Zr)-NH2 was mixed with TMC in n -hexane solution, covalent bonds formed between the amino groups of UiO-66(Zr)-NH2 and acyl chloride groups of TMC.32-34 These bonds led to the formation of a uniform and sturdy surface layer that contained MOF nanoparticles affixed in the polyamide matrix. The formed covalent bonds were identified in the XPS profiles of TMC-UiO-66(Zr)-NH2 (Figure 2). The peaks at 284.8, 286.5, and 288.7 eV in the C 1s XPS profile of UiO-66(Zr)-NH2 corresponded to the C–C, C–N, and O=C–O bonds, respectively (Figure 2a).32, 33 The intensity of the characteristic peak of the C–N bond in the XPS spectra of TMC-UiO-66(Zr)-NH2 was significantly higher than that in the XPS spectra of UiO-66(Zr)-NH2 (Figure 2b). This indicated the formation of C–N bonds during the reaction of UiO-66(Zr)-NH2 with TMC. The N 1s XPS profile of UiO-66(Zr)-NH2 presented a single peak at 399.5 eV, which was ascribed to the –NH2 groups (Figure 2c). By contrast, an additional peak at 401.5 eV was observed in the N 1s spectra of TMC-UiO-66(Zr)-NH2, and that further confirmed the formation of O=C–N bonds during the reaction of UiO-66(Zr)-NH2 with TMC (Figure 2d). The presence of the new peak at 1730 cm−1 in the FTIR spectrum of TMC-UiO-66(Zr)-NH2 (Supporting Information, Figure S6a) also indicated the formation of covalent bonds between UiO-66(Zr)-NH2 and TMC. Furthermore, the positions of the peaks in the XRD spectra of TMC-UiO-66(Zr)-NH2 and UiO-66(Zr)-NH2 did not change significantly, which indicated the negligible effect of the reaction on the crystal structure of UiO-66(Zr)-NH2 (Supporting Information, Figure S6b). The 1H NMR spectrum further confirmed that a reaction occurred between TMC and UiO-66(Zr)-NH2 (Supporting Information, Scheme S1 and Figure S7). The covalent bonds that formed during the reaction tightened the interaction between UiO-66(Zr)-NH2 and interfacial polymer layer.