Altın nanoparçacığı içeren polimer kompozitlerinin hazırlanması ve karakterizasyonu

In this study, light-assisted synthesis of gold nanoparticles in polymer films is demonstratedand characterization of gold nanoparticle-polymer composites using various techniques isshown. There are various methods introduced for the synthesis of gold nanoparticles insolution and their integration to the polymer films afterwards. However, synthesizing goldnanoparticles directly inside the polymer matrix is more advantageous for the production ofpolymer-nanoparticle composites.An advantage of synthesizing gold nanoparticles within polymer films is the opportunity ofphoto-patterning. Films having patterns made of regions with and without gold nanoparticlescan be produced, using masks designed to cut off the radiation at desired places. Suchpatterned films were investigated with scanning electron microscope (SEM) and dark regionsbetween irradiated regions and masked regions were observed. These dark regions are shownto be ?ion depleted regions?, where gold ions diffuse through irradiated regions during theirradiation. These regions of about 10 ? m width, suggests a very large distance for gold ionsto diffuse through a rigid matrix like Poly(methyl methacrylate)(PMMA), which is veryinteresting. Supporting evidence for the existence of these regions was obtained fromfluorescence studies with Rhodamine 6G molecule and x-ray electron spectroscopy (XPS).The observations made through the formation of ion depleted regions can be used to estimatethe diffusion constant of gold ions inside the PMMA matrix. Also the presence of iondepleted regions indicate the stability of photo-patterns created on the polymer film againstsmearing during light exposure after the production, by setting an upper limit to the criticalfeature size.During the characterization of gold nanoparticle-polymer composites, the electrical propertiesof PMMA with and without gold nanoparticles were investigated using charge resolved XPS,while applying external bias to the films with and without gold nanoparticles to probe thecharging properties of the films. An enhancement of conductivity of PMMA films containinggold nanoparticles was observed using this technique. Additionally charge resolved XPStechnique was also used to determine the charge storage characteristics of the polymersurfaces, which is important for the identification of charging mechanisms during contact andother electrification processes. It was shown that the PMMA surface is very susceptible tonegative charging and even native negative charges on the PMMA surface can be observedprior to any treatment. Also when the surface is charged carbon and oxygen atoms of thecarbonyl and methoxy groups of PMMA were observed to behave differently from thebackbone of the polymer, which shows the chemical specificity of the charge accumulatingspots on the surface.