Photocurable Polyurethane Acrylated Composites with Ionic Liquid-Laden Metal–Organic Framework for Energy Storage and Electronic Applications

Polymer composites are suitable strategies for the development of advanced materials with tailored electrical properties, particularly relevant in electronics areas such as sensors, actuators, and solid electrolytes for energy storage applications. In this study, composites based on a polyurethane acrylated (PUA) matrix with metal–organic framework (MOF) nanoparticles (MOF-808) were prepared. Different amounts of the ionic liquid 1-ethyl-3-methylimidazolium thiocyanate ([EMIM][SCN]) were incorporated into the pores of the MOF-808 structure to tune the electrical response of the composite. The composites PUA/MOF/IL underwent characterization through electron microscopy for morphology analysis, X-ray diffraction (XRS) and Fourier transform infrared spectroscopy (FTIR) for the determination of the physical–chemical properties, and broadband dielectric spectroscopy (DRS) for assessing dielectric and conductive behavior. At the nanoscale, it is shown that when IL is infused into the MOF nanoparticles, the MOF pores saturate and the remaining IL stabilizes as an interphase on the surface of the MOF particles. DRS reveals that the main α-relaxation of the PUA chains is affected by the presence of MOFs and IL, while the secondary β-relaxation, related to local fluctuations, remains unchanged. Furthermore, the conductivity process is dependent on the MOF:IL weight ratio, and the MOF saturation by IL impacts the dielectric behavior of the nanocomposites. This study provides valuable nanoscale insights into the interaction between MOF and IL and the dielectric behavior of PUA/MOF/IL composites, emphasizing the impact of MOF and IL additives on the relaxation processes and, in particular, on the electrical conductivity. The electrical properties of the developed materials show significant potential for their use as solid polymer electrolytes.