Polymer Assisted Synthesis And Self-assembly Of Gold Nanoparticles And Their Applications

Controlled synthesis and self-assembly of gold nanoparticles(Au NPs)are important topics in the field of noble nanomaterials.The surface modification of Au NPs plays an important role in the synthesis and assembly.Generally,small molecule ligands were used to modify Au NPs to tune the synthesis and assembly.Polymer with the nature of complex solution behavior,full of functional groups and can be easily functionalized,which makes it an ideal candidate as the ligand to induce the synthesis and assembly of Au NPs.Polymer chain could absorb on the certain surface of the crystal,which may induce the spatial distribution of the metal precursor,leading to the formation of Au NPs with special morphology.This will help us get a better understanding of crystal growth mechanism.By using polymers as the surface ligands,spatially anisotropic building blocks were prepared and new non-covalent forces were introduced into the assembly system.By mediating the interaction between the building blocks,the assembly behavior of the anisotropic building blocks can be precisely controlled.This could offer a new approach to regulate the assembly of Au NPs in multiscale.Multifunctional organic-inorganic hybrid materials for applications in various fields would be easily constructed by the combination of functional polymer materials and Au NPs.The thesis mainly includes three parts:1.Hierarchical raspberry-like Au nanostructures with tunable size and uniform shape was synthesized via a seed-mediated growth approach by using quaternized chitosan(QCS)as surfactant and 5-bromosalicylic acid(5-BrSA)as co-surfactant.The relationship between the morphology and the concentration of the surfactant was studied.This hierarchical structures with irregular convex rough surface is rich in hotspot that can largely enhance the Raman scattering signal of 4-mercaptopyridine(4-MPy).2.Asymmetrically functionalized gold nanorods(Au NRs)was prepared via a controlled ligand exchange method by using mercapto polyethylene glycol(HS-PEG)as the ligand.The assembly behavior of the asymmetrically functionalized Au NRs on the PEG-modified substrate can be precisely controlled.Two different oriented closely packed Au NRs arrays with large area were obtained and the formation mechanism was studied.The SERS property of the array was also studied.3.Pt-Au Bimetallic NPs were prepared via seed mediated method by using Au NRs as seed.Pt-Au Bimetallic NPs show strong plasmon resonance and outstanding catalytic properties.The relationship between the optical and catalytic property and the morphology of Pt-Au Bimetallic NPs were studied.The bimetallic nanoparticles were further loaded on the hydrophilic-modified poly(vinylidene fluoride)(PVDF)membrane to fabricate organic-inorganic composite membrane.The composite membrane can be used as a recyclable catalyst and also to separate water from the oilwater emulsion.