▎ 摘　　要

The current investigation has presented a new synthesis technique to prepare pentaethylene glycol-treated graphene nanoplatelets (PEG-GnP) and pentaethylene glycol thermally treated graphene (PEG-TGr). The covalently functionalized (PEG-GnP and PEG-TGr) at various mass concentrations were dispersed in distilled water by ultrasonication for preparing nanofluids. The functionalization process effectiveness was established by using the surface characterization and morphology analysis with FTIR, Raman spectroscopy, FE-SEM, and TEM. The thermo-physical properties and stability of functionalized nanofluids were investigated utilizing numerous measuring devices. Dispersion stabilities of the functionalized nanofluids were observed for a long period of time (30days). Water-based functionalized nanofluids revealed very Newtonian behavior with the increment in the experimental values of dynamic viscosity as temperature decreases and mass concentration of sample increases. Thermal conductivity of GnP and TGr dispersed in distilled water nanofluids show the enhancement of 32 and 31%, respectively, at 50 degrees C and 0.1% mass concentration.