Synthesis, characterization, and high potential of 3D metal–organic framework (MOF) nanoparticles for curing with epoxy

Abstract

In this study, the potential of microporous 3D metal–organic framework (MOF) for curing epoxy resin has been discussed. First, MIL-101 (Cr), a chromium based MOF, was synthesized under hydrothermal condition and then characterized by using Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and thermogravimetric (TGA) measurements. Epoxy nanocomposites containing 0.1, 0.3 and 0.5 wt% of MOF nanocrystals were subsequently prepared and their curability was studied in terms of the universal dimensionless Cure Index (CI) criterion under nonisothermal differential scanning calorimetry (DSC). Based on calculations made on the basis of the CI, epoxy nanocomposites containing 0.1, 0.3, and 0.5 wt% of MOF were labeled Good and Excellent thanks to an enhanced chemical interaction between MOF and epoxy matrix, where the heat of cure in the system was surprisingly even higher than that of the neat epoxy. It was demonstrated that introduction of MOF into epoxy significantly improved the heat release during crosslinking process of epoxy, as indicated by a 63% rise in the enthalpy of cure at MOF loading of 0.1 wt%. Addition of thermally stable MOF nanomaterials to the epoxy resin improved thermal decomposition resistance of epoxy. Up to 0.3 wt% loading, the system revealed acceptable thermal stability at elevated temperature featured by more residue remained at the end of test, while sample containing 0.5 wt% MOF resisted against decomposition at early stages of degradation due to higher thermal stability of MOF with respect to epoxy resin.