Investigation of photochromic behavior of biodegradable MoO3/Sg-St nanocomposites

Abstract

Now a days, the synthesis of α-MoO3 based photochromic materials are a subject of many investigations as they can modulate solar light transmittance automatically, according to wavelength, in response to UV irradiation and hence can adjust the indoor atmosphere to reduce the consumption of energy. In the present work, an attempt has been made to investigate the relation between coloring/bleaching rates of self-supporting, highly flexible α-MoO3/Sg-St (Sago-Starch) nanocomposites (NCs) fabricated via solution casting technique. The prepared samples were characterized using FESEM, XRD, FTIR, and UV–Vis–NIR spectroscopy. Nano-sheet morphology of the synthesized sample was ascertained using FESEM while XRD reveals the orthorhombic structure of MoO3 with an average crystallite size of 135 nm. The average thickness of nanosheets comes out to be 111.57 nm (using FESEM). FTIR spectroscopy depicts the strong interaction between α-MoO3 and Sg-St polymer confirming the successful incorporation of α-MoO3 in the Sg-St matrix. The value of Eg for virgin Sg-St comes out to be 4.56 ± 0.12 eV and decreases to 2.54 ± 0.07 eV for 10 wt% α-MoO3/Sg-St NC while the refractive index (n) increases from 1.53 for virgin Sg-St to 2.11 for 10 wt% α-MoO3/Sg-St NC at 450 nm wavelength. The value of tensile strength for virgin Sg-St is found to be 9.54 which increases to 17.07 after incorporation of 1 wt% of α-MoO3 suggesting the strong interfacial interaction of nanofiller with polymer matrix. The prepared NCs exhibited a fast response to UV exposure (<30 s) with high coloration efficiency; which makes them a highly acceptable material for photochromic smart windows. The maximum coloration efficiency ∼0.6071 and RDR (%) value of 75.29 corresponds to 1 wt% α-MoO3/Sg-St NC.