Preparation and Characterization of Graphene Nanoplatelets Nanofluids in the Presence of Polyethylene Glycol-Derived Polyhedral Oligomeric Silsesquioxane

In this study, rheological and thermophysical properties of water-based and ethylene glycol (EG)-based graphene nanoplatelets (GNP) nanofluids were compared. Ultrasound-assisted preparation of aqueous and EG-based GNP nanofluids at high nanoparticle concentrations was performed in the presence of polyethylene glycol-derived polyhedral oligomeric silsesquioxane (PEG-POSS) as a stabilizer, for the first time in literature. Ultraviolet-visible (UV-Vis) spectrophotometry and zeta potential measuring device (Zetasizer Nano) were employed for the evaluation of stability performance of the nanofluids. Surface tension values of the nanofluids were measured by pendant drop method. The inclusion of PEG-POSS resulted in surface tension reduction up to 4.5% for aqueous nanofluids, whereas the surface tension of EG-based nanofluids increased up to 11.5%. The highest thermal conductivity enhancement of 32% was measured for EG-based 2.0 wt% GNP nanofluids, using 3 omega method. The results suggest that the addition of PEG-POSS as a stabilizer improved the thermal conductivity of EG-based GNP nanofluids significantly.