Preparation of VO₂ Nanoparticles with Surface Functionalization for Thermochromic Application

Abstract

This recent work investigates on the modification of metal oxide particles surface by the addition of amorphous coating layer. This core-shell structure is expected to decrease particles aggregation and increase their distribution in polymer matrix. VO₂ particles were firstly prepared via hydrothermal process with 87% yield and XRD analysis showed that VO₂ monoclinic was obtained with 100% of purity. XPS technique also showed that the surface of VO₂ particles contains -OH group which is promising to form the strong covalent bond with silane coupling agent. The addition of functional groups on the surface of VO₂ particles was then performed by the grafting of (3-Aminopropyl) triethoxysilane (APTES) via the silane anchoring group with 1:10 weight ratio VO₂/APTES. The effect of solvent was also studied by using 10 ml of different solvent such as distilled water, ethanol and chloroform during surface coating. The TEM image clearly shows the presence of the thick organic layer on VO₂ particles and as a result, the core-shell structure was perfectly identified. The round shape of coated VO₂ particles was detected with small aggregation by SEM imageries. Furthermore, the presence of characteristic absorption band of C-H, Si-O-C, Si-O-Si and NH stretching in the FTIR spectra of coated VO₂ particles confirmed the existence of APTES on the surface of VO₂ particles prepared in distilled water and ethanol.