HAVA SU ARA YÜZEYİNDE ÇEŞİTLİ NANOYAPILARIN KENDİLİĞİNDEN KÜMELEŞEREK OLUŞTURULMASI VE ELDE EDİLEN NANOYAPILARIN KARAKTERİZASYONU

Abstract

In addition to the nanostructures which are formed in solution by amphiphilic molecules such as lipids and peptides, it is known that self-aggregated nanotubes and nanostructures whose morphologies are helically shaped or plate can be obtained also in the air-water interface. According to the functions of self assembled nanostructures which are formed in both solution and interface, these nanostructures have usage in many fields such as microelectronics, sensor and biomedical applications. At the same time, due to the functional groups of amphiphilic molecules and environmental conditions it is also known metal cations which are in the subphase can be reduce at the air-water interface by these molecules. Within this study, we aimed to investigate the behaviour of Aqua molecule which is synthesized by our group at the air-water interface with different subphase conditions. In this part of the study, synthesis of Aqua molecules was carried primarily by the synthesis procedure that was determined with the previous studies. Then a certain amount of chloroform solution of Aqua was spread on the Ag2SO4 and Li2SO4 subphases whose concentration was 1 mM and pH values were 9-7-3 and water at pH values again 9-7-3, and compression isotherms were obtained at Langmuir Trough. In addition, analyses of the morphologies of organic nanostructures were aimed which were formed by the self assembly process of pH sensitive Aqua molecules on the subphases that were prepared with different salts and at different pH values and at various surface pressures. In this context, a certain amount of chloroform solution of Aqua was spread on the Ag2SO4 and Li2SO4 subphases whose concentration was 1 mM and pH values were 9-7-3 and water at pH values again 9-7-3 and the interfaces were compressed to the surface pressures 0, 5 and 10 mN/m at Langmuir Trough. Then Aqua assemblies which were formed at these surface pressures, were transferred onto solid surfaces by using Blodgett technique and morphologies of assemblies were examined by AFM. In another study, to form denser assemblies at the air-water interface, the amount of Aqua which was spread on the air-water interface was increased and we aimed to investigate the effect of the concentrations of Ag2SO4 and Li2SO4 on the morphologies of assemblies of the Aqua. In this respect, Aqua molecules were spread onto subphases which were prepared with Ag2SO4 ve Li2SO4 at the concentrations of 1 and 10 mM at pH 7 and after the compression of molecules at the interface until reaching the minimum interface area, the assemblies were transferred onto solid surfaces by using Blodgett technique and morphology analyses of assemblies were made with SEM. As intermediates during the formation of the tubular structures, helical ribbon nanostructures were obtained by Aqua molecules on the subphases which had low concentration and they were found to be in the micron size. At the same time, for the Ag2SO4 subphase system, the experiment was carried out at high pH so the effect of pH on the assemblies was investigated. When the pH was increased it was determined that Aqua molecules formed sheet like structures rather than helix ribbon-shape structures at the air-water interface. In another part of the study, Ag⁺ ions which were in the subphase, Ag⁺ ions reducing capability of Aqua molecules and to determine the parameters affecting the reduction reaction were aimed. In this section on the Ag2SO4 subphases whose concentrations were 1 and 10 mM and pH values were 11-7-3, 24 and 48 hours reaction times were selected and after the organic and inorganic nanostructures were transferred onto solid surfaces, their analysis were performed by TEM. To assess the effects of interface area on the silver particle morphology after the Aqua molecules were spread on the Ag2SO4 subphases whose concentrations were 1 mM and pH values were 11 and 3, molecules were compressed from 75 Å2 to 30 Å2 per molecule and the experiments were performed during 48 hours. The analysis of the structures which were formed at the air-water interface was made by TEM, again. In the results, it is investigated that varying parameters did not have any effect on formation of silver nanoparticles but they caused some changes on size or morphologies of the particles. At the same time with the help of the information given in the literature, about the mechanism of the reduction reaction of Ag⁺ ions by Aqua molecules at the air-water interface, some comments were made.