Optical Properties of ZnO Nanoparticles Capped with Polymers

Abstract

Optical properties of ZnO nanoparticles capped with polymers were investigated. Polyethylene glycol (PEG) and polyvinyl pyrrolidone (PVP) were used as capping reagents. ZnO nanoparticles were synthesized by the sol-gel method. Fluorescence and absorption spectra were measured. When we varied the timing of the addition of the polymer to the ZnO nanoparticle solution, the optical properties were drastically changed. When PEG was added to the solution before the synthesis of ZnO nanoparticles, the fluorescence intensity increased. At the same time, the total particle size increased, which indicated that PEG molecules had capped the ZnO nanoparticles. The capping led to surface passivation, which increased fluorescence intensity. However, when PEG was added to the solution after the synthesis of ZnO nanoparticles, the fluorescence and particle size did not change. When PVP was added to the solution before the synthesis of ZnO nanoparticles, aggregation of nanoparticles occurred. When PVP was added to the solution after the synthesis of ZnO nanoparticles, fluorescence and particle size increased. This improvement of optical properties is advantageous to the practical usage of ZnO nanoparticles, such as bioimaging.

Facile Synthesis of ZnO Nanoparticles and Their Photocatalytic Activity

“…Figure 1 shows the XRD patterns of the prepared ZnO nanoparticles (Z4, Z5 and Z10). The XRD patterns of the ZnO nanoparticles were in agreement with reported data, [3][4][5][6][7] suggesting that all samples were the hexagonal phase (JCPDS 01-075-0576 wurtzite structure). No peaks for other phases were observed.…”

“…[5][6][7] Obtaining monodisperse nanoparticles and controlling the particle size and shape are important factors for utilizing ZnO.…”

Optical Properties of Afterglow Nanoparticles : , Capped with Polyethylene Glycol

“…The increased specific surface area leads to the nonradiative transition of surface defects through the energy levels and to the vibration of water molecules, which decreases the afterglow property. The addition of PEG to the solution in which the nanoparticles were dispersed caused capping nanoparticles [33,34]. Surface passivation by polymer coating would be effective to prevent such a reduction of afterglow properties [19][20][21].…”

Interfacial effect: magnetism in pure ZrO2, ZnO and SiO2 coated core/shell/shell hybrid nanoparticles

“…In this study we have chosen ZnO as the first shell particularly since it is a popular wide band gap semiconductor and has several favorable properties: good transparency, high electron mobility, wide band gap, strong room-temperature luminescence and magnetic properties etc. [25,26]. Vollath and Szabo [27,28] reported on the synthesis of different core-shell nanostructures based on Al 2 O 3 and ZrO 2 by two sequential microwave plasma reactors [29].…”