Preparation Of Noble Metal Nanoarrays By Block Copolymer And Its SERS Performance

Ordered noble metal nanostructured arrays have attracted increasing interest due to their potential applications in nergy storage devices, photocatalysis solar cells and metal-enhanced fluorescence. Thereinto, how to fabricate these ordered arrays with controlled shape, size is a challenging problem. So far, block copolymer has received considerable attention because of thermodynamic incompatible properties between different blocks, which makes the block copolymer occur micro-phase separation. The self-assembled block copolymer has the advantages to provide ordered arrays of 5¹00 nm length scales with a simple low cost and scalable process. In this thesis, the self-assembled polystyrene-block-poly?4-vinylpyridine??PS-b-P4VP? ordered patterns were prepared by solvent annealing method. Then, the uniform Au, Ag and Au-Ag nanocluster arrays utilizing self-assembled PS-b-P4 VP thin films as template and their application as surface-enhanced Raman scattering?SERS? substrate. Au, Ag and Au-Ag nanocluster arrays were fabricated by in situ heating and UV light-assisted reduction of metal precursor which has been selectively loaded on the surface of PS-b-P4 VP thin film. A series of reaction conditions?the concentration of the precursor, the reaction temperature, the reaction time and other factors? were investigated to control the orderly preparation of Au,Ag, Au-Ag nanocluster arrays, which influence the size, aggregation state, density of Au,Ag and Au-Ag nanoparticles. Besides, the Au, Ag and Au-Ag nanocluster arrays prepared in different reaction conditions have different SERS performance.The main work completed in this thesis could be summarized as following:The Au nanocluster could be perpared by self-assembled ordered PS-b-P4 VP thin films as template, which had excellence SERS perfprmance. Uniform and high density Au cluster arrays were fabricated by in situ heating and UV light-assisted reduction of Au precursor?0.024 mol·L-1 HAuCl4 solution? at 80 oC with three hours. The array was then used as SERS substrate for detecting a model molecular?R6G?, which shows an excellent SERS performance with high reproducibility. The detection limit could be as low as 10-8mol·L-1. The signals collected at 121 points over a 50 ?m × 50 ?m area give relative standard deviation lower than 11 %. The SERS substrate of Au nanocluster array could also could be used to detect CV, 4-ATP and 2-NAT, because of its outstanding universality.The Ag nanocluster could be perpared by self-assembled ordered PS-b-P4 VP thinfilms as template, which had excellence SERS performance. Uniform Ag cluster arrays were fabricated by in situ heating and UV light-assisted reduction of AgNO₃ aqueous ethanol?0.015 mol·L-1? at 80 oC with three hours. The Ag nanocluster arrays were used as SERS substrate for detecting a model molecular?R6G?. The detection limit could be as low as 10-9 mol·L-1, and the enhancement factor?EF? up to 1.33×107.. The signals collected at121 points over a 50 ?m × 50 ?m area give relative standard deviation lower than 13 %.The SERS substrate of Au nanocluster array could also was used to detect CV, 4-ATP and2-NAT, because of its outstanding universality.3. The Au-Ag nanocluster could be perpared by as prepared Au/PS-b-P4 VP thin films as template, which had excellence SERS performance. Uniform Au-Ag nanocluster arrays were fabricated by in situ heating and UV light-assisted reduction of AgNO₃ ethanol?0.01mol·L-1? at 80 o C with 1h. The Au-Ag nanocluster arrays were used as SERS substrate for detecting a model molecular?R6G?. The detection limit could be as low as 10-10 mol·L-1,and the enhancement factor?EF? up to 3.59×107. The signals collected at 121 points over a50 ?m × 50 ?m area give relative standard deviation lower than 10.5 %. The SERS substrate of Au nanocluster array also was used to detect CV, 4-ATP and 2-NAT, because of its outstanding universality.