ABSTRACT Polymer/metal–organic framework (MOF) mixed matrix membranes (MMMs), where MOF materials are doped into a polymer matrix, have great potential in gas separation, electronic devices, sensing, and other fields. To extend the application of polymer/MOF MMMs as optical films for sensing, an in‐depth investigation of their optical properties is necessary. In this work, PMMA/ZIF‐8 composite films are prepared via in‐situ polymerization or one‐pot synthesis, with varied ZIF‐8 loading amounts. The structure, morphology, gas adsorption capacity, thermal stability, and optical properties of these composite films are characterized. The results showed that the ZIF‐8 crystals can be uniformly dispersed in these composite films. Nitrogen adsorption measurement also confirms this uniform dispersion, where the adsorption capacity of the composite films increases with increasing ZIF‐8 loading amount. Additionally, thermogravimetric analysis proves that the introduction of ZIF‐8 considerably enhances the thermal stability of the composite films. Further, the measurement results show that the refractive index of the composite films increases with increasing ZIF‐8 loading amount at the wavelengths of 632.8 and 1550 nm, while the optical loss decreases at low loading amounts and slightly increases at high loading amounts due to the scattering effect. This work provides inspiration of MMM‐based optical films for gas sensing.
Hai et al. (2026) studied this question.