Polymer Auxiliary Construction Of Metal Nanoparticles Arrays And The Research For Composite Method

The metal nanostructures on surface have aroused extensive interests in a wide range of applications, such as sensors, surface enhanced Raman spectroscopy, surface enhanced fluorescence, photovoltaics, and waveguide materials. These applications are mainly ascribed to their unique optical properties known as surface plasmon resonance, which is affected by the size, shape, and distance of the involved metallic nanostructures. The random structures lack design criteria and reproducibility, and cannot be applied in all engineering field. Therefore, finding a simple and versatile method to prepare ordered metal nanostructure is of highly importance. A lot of methods have been employed to fabricate ordered metal nanostructures, which combined metal deposition and lithography techniques, such as electron-beam lithography, nanoimprint lithography, photolithography, and colloidal lithography. Nevertheless, metal deposition always needs precise equipment. Template-assisted self-assembly of metal nanoparticles on patterned polymer has been proposed to be a facile method for fabricating metal nanostructures. Among the patterned polymers available for the template of metal nanoparticles, block copolymer thin films are the most used templates to control the arrangement of nanoparticles, and a lot of large-area ordered NP cluster arrays have been prepared by introducing the Au NPs on block copolymer patterns. The morphology and size of the block copolymer templates can be controlled by varying the molecular weight and block composition of the block copolymer. However, the adjustable size range of each morphology is limited, which goes against the large-scale structural control for the metal patterns. Colloidal lithography technique has been demonstrated as a facile, low-cost, and efficient method for large-area fabrication of polymer arrays. The size, separation distance and period of the obtained nanostructure arrays can be tuned by regulating the experimental conditions. Thus, it is feasible and convenient to fabricate the large-area metal nanoparticle arrays by introducing the metal nanoparticle arrays to the polymer template arrays created by colloidal lithography through different composite method.In chapter 2, The PDMAEMA brush/Ag nanoparticles hybrid arrays are fabricated by in situ reduction of Ag NPs in the polymer brush patterns. The PDMAEMA brushes were grafted in substrate by surface initiated atom transfer radical polymerization. After the introduction of Ag NPs by in situ reaction, the PDMAEMA brush/Ag nanoparticles hybrid films were obtained. The polymer brush patterns were prepared colloidal lithography, and the structure parameters of the polymer brush could be easily controlled by changing the etching time and diameter of the colloidal spheres. The PDMAEMA brush/Ag nanoparticles hybrid arrays exhibit the same morphology of the polymer brush patterns, so various Ag nanoparticle arrays can be fabricated by the patterned polymer brushes with various morphology and structure. The optical properties of the polymer/Ag NP arrays can be changed by the period of the arrays. To investigate the effect of the polymer/Ag NP arrays for surface-enhanced fluorescence, the FITC labeled BSA was bound to the silver nanoparticles, and the fluorescence intensity of the polymer/Ag NP hybrid arrays is 5 times greater than the polymer/Ag NP hybrid films.In chapter 3, we report a novel method to fabricate gold nanoparticle arrays by incorporating gold NPs into PDMAEMA brush patterns by host-guest interaction. The β-cyclodextrin ligand of gold nanoparticles serves as host and dimethylamino groups of PDMAEMA serves as a guest to form hybrid films by host-guest interaction.. The structure parameters of gold nanoparticles nanopatterns mediated by polymer brushes could be arbitrarily tuned by tailoring the etching time or size of colloidal spheres in the process of colloidal lithography. The effect of various structures on the optical properties of gold nanoparticle arrays has been discussed. The direct utilization of the PDMAEMA brushes as guest avoids a series of complicated synthesis, in comparison with modification of other groups as guest in previous studies. Besides, gold nanoparticles mediated by the polymer brushes can be grafted on various macroscopic substrates and micro-nano structures, which extend its applications.In chapter 4, we presents a novel method to prepare large-area Au NP cluster arrays based on colloidal lithography and template-guided self-assembly technique. The NP cluster arrays were fabricated by introducing Au NPs onto the quaternized PDMAEMA brush templates via electrostatic interaction. The polymer brush templates showed good adsorption capacity and could directly adsorb Au NPs with different sizes(10-55 nm). The structure parameters of NP cluster arrays, including diameters, periods and distances, could be easily controlled by polymer brush templates created by colloidal lithography. Moreover, the number of Au NPs in cluster could be arbitrarily tuned by varying the surface area of the polymer brush templates. The demonstrated method paves the way to low-cost and high throughput production of sensor chips.