Needle into the line: Intercalation and dispersion of UV-curable ionic liquid monomers in graphene for sensing coating applications

Imidazolium ion-based ionic liquids (ILs) have been employed to enhance the dispersion stability of graphene in composite materials, leveraging their π-π conjugation and cation-π interactions with graphene. In this study, a UV-curable ionic liquid monomer (UV-IL monomer), 1-[(6-methacryloyloxy)-hexyl]-3-methylimidazolium chloride, was successfully synthesized and characterized using 1 H NMR and FT-IR spectroscopy. To improve the dispersion stability and electrical conductivity of reduced graphene oxide (rGO), graphene oxide (GO) was chemically modified by grafting with an amino-functionalized ionic liquid, yielding reduced modified graphene oxide (RMGO) through covalent and non-covalent interactions. The resulting RMGO was incorporated into a UV-cured coating to fabricate a conductive sensing material. The conductive mechanism and sensing properties of the coating were systematically investigated. Results demonstrate that the conductivity of the coating arises from the synergistic effect between RMGO and the ionic liquid. The sensing coating exhibited excellent temperature responsiveness, with its response curve following a combined function derived from the Vogel-Tammann-Fulcher (VTF) equation for ionic liquids and the linear resistance-temperature relationship of graphene. These findings highlight the promising potential of this composite for temperature-sensing applications.