Rachel Yerushalmi-Rozen

Suspensions of carbonaceous nanoparticles (NPs) in ethylene glycol (EG) can be used as colloidal inks for additive manufacturing and nano-fluids for heat-transfer applications. While micellar solutions of surfactants are often used for suspension of the NPs in water, micellization of surfactants in EG is suppressed as compared to aqueous solutions and a well-defined critical micellization concentration (CMC) is often not observed. Unlike the surfactants, a di-block copolymer comprising a poly(ethylene glycol) monomethylether methacrylate (PEGMA) segment, 2-(diethylaminoethyl) methacrylate (DEAEMA) and butyl methacrylate (BMA), poly(O950)-b-(DEAEMA-co-BMA) was found to assemble into spherical micelles in EG. Surface tension measurements show a well-defined CMC that depends on the volume fraction of EG. Cryogenic transmission electron microscopy and dynamic light scattering show the presence of spherical micelles with a diameter that reduces with the volume fraction of EG. The micellar solutions were further used for suspending carbonaceous NPs of different geometry and characteristic dimensions: C₆₀ fullerenes, multi-walled carbon nanotubes, and nanodiamonds. The flow behavior of the suspensions exhibits a relatively low viscosity and mostly Newtonian behavior due to strong interaction between the NPs and the micelles. These suspensions may be used as colloidal inks for two-dimensional and three-dimensional printing.