Study On The Controllable Preparation Of Metal Nanoparticles By Molecular Self-assembly Method

Metallic nanoparticles usually can exhibit unique optical, electrical and acoustic properties due to the small size and surface effects, which have been widely applied in catalysis, surface-enhanced Raman scattering and biological sensing. How to realize the preparation of metallic nanoparticle with controllable shape, size, composition, structure and dispersion has become a hot research topic. Self-assembled monolayers(SAMs) are two-dimensional supermolecule structures, which are spontaneously formed by the standalone and disorder linear polymeric compounds terminated by different functional groups. SAMs are very suitable to controllably design and prepare the order, uniform and periodic nanostructures in much small scale. In this thesis, the preparation recipes of mono- and multi- component SAMs have been studied, while the SAMs have been used to controllably prepare metallic nanoparticles.Firstly, the preparation recipes of some mono-component silane SAMs with different carbon chain length have been studied. The relations between the surface properties and the preparation conditions have been studied. It is found that the temperature, solutions, the content of water and growth time will have great influence on the quality of grown SAMs. Among the prepared SAMs, octadecyltrichlorosilane SAMs can resist the growth of metallic nanoparticles by atomic layer deposition. The electrochemistry methods have been carried out to analyze the growth of octadecyltrichlorosilane SAMs and characterize the coverage and holes distribution. The holes in the octadecyltrichlorosilane SAMs have been used to achieve area-selectively atomic layer deposition of noble metal nanoparticles. The density and distribution of deposited nanoparticles have been successfully controlled by the growth time of octadecyltrichlorosilane SAMs.Secondly, the preparation recipe of(3-Mercaptopropyl) trimethoxysilane SAMs has been investigated. The effects of(3-Mercaptopropyl) trimethoxysilane SAMs on the growth of metallic nanoparticles by atomic layer deposition have been studied. The results show that the nucleation stage of metallic nanoparticles will be shortened and the growth rate will increase due to the terminated-SH groups have strong chemical adsorption with the metallic atoms.Furthermore, the mixed octadecyltrichlorosilane and(3-Mercaptopropyl) trimethoxysilane SAMs have been considered to control the growth of metal nanoparticles, as octadecyltrichlorosilane and MPTS SAMs will resist and assist the growth of metal nanoparticles, respectively. The step-by-step preparation and template printing methods have been used to generate mixed SAMs patterns. The effects of preparation parameters of the mixed octadecyltrichlorosilane and(3-Mercaptopropyl) trimethoxysilane SAMs on the size distribution of metallic nanoparticles have been studied.At last, the mixed octadecyltrichlorosilane and(3-Mercaptopropyl) trimethoxysilane SAMs prepared by step-by-step preparation and template printing methods have been introduced to controllably prepare Au nanoparticles. The results show that the mixed SAMs can greatly improve the aggregation of Au nanoparticles. The composition ratio between the two SAMs can be used to control the density and distribution of Au nanoparticles, which is benefit for the application in surface-enhanced Raman scattering.The preparation recipes of methyl and sulphur silane SAMs have been studied. The prepared SAMs have been used to control the size distribution and density metallic nanoparticles. Moreover, the mixed SAMs containing different terminated functional groups have also been used in the controllable preparation of metal nanoparticles. The thesis can provide a new way for the controllable preparation of metallic nanoparticles.