Tuning the Optical and Rheological Properties of Fullerene C60/Poly (Vinyl Pyrrolidone) Nanofluids via Inclusion of Nanogold

Abstract

In this article, development of nanogold (NG) containing fullerene C60 nanofluids (NFs) with poly (vinyl pyrrolidone) PVP polymer in water via a wet chemical route is reported and studied their rheo-optical properties. An inclusion of NG into a C60:PVP nanofluid thus results in a gold (Au) surface plasmon resonance (SPR) enhanced π → π* C60 (sp2) electron transition over 250–450 nm of absorption spectrum in water. Evolution of a broad Au-SPR band in the 450–750 nm region signifies that a controlled Au3+ → Au reduction reaction had occurred on it and was carried in C60:PVP NFs. The average maximum wavelength value has thus varied along with a molar extinction coefficient in a function of the Au-uploads and shape and size of the flocculates in the resulting Au:C60-PVP NFs. A systematic rheological study performed on the Au:C60-PVP NFs in water by varying the NG content up to 85.0 μM reveals a non-Newtonian behavior with an enhanced yield stress is a signature of Bingham flow. NG of different shapes serves as filler in C60:PVP NFs so as it adapts tailored shear viscosity. The shear viscosity relaxes slowly to the base value on increasing the shear rate from 10 to 100 s−1 as it leads to breaking up of soft Au:C60-PVP assemblies into a fine structures. Synthesis of Au:C60-PVP NFs with various Au-contents could be potential nanostructure hybrid composite materials for development of photovoltaic nanodevices.