In situ Preparation of Silver Nanoparticles in Polystyrene-b-poly(2-vinylpyridine) Films over Chemically Patterned Substrates

The present work reports the in situ fabrication of Ag nanoparticles (AgNPs) in polystyrene-b-poly(2-vinylpyridine) (PS-b-P2VP) over pre-patterned hydrophobic stripes on a hydrophilic glass surface. Microcontact printing (μCP) using octadecyltrichlorosilane (OTS) as “ink” was used to obtain these chemically modified substrates. A comparison of the results of the PS-b-P2VP self-assembly over a bare glass substrate and a pre-patterned glass substrate demonstrated the influence of the pattern on the film morphology. Polymeric films of Ag⁺ and PS-b-P2VP were prepared on a pre-patterned substrate and heated at 150 °C to enable the self-reconstruction of the polymeric matrix and the in situ formation of AgNPs (average particle size of approximately 100 nm). The AgNP/PS-b-P2VP thin films were characterized using UV-Vis spectroscopy and atomic force microscopy. The results demonstrate that the concentration of the solutions of Ag⁺/PS-b-P2VP used to prepare the films strongly influences the morphologies and dispersion of AgNPs. Moreover, the surface-enhanced Raman spectroscopy (SERS) activity of the fabricated polymer nanocomposites using Nile Blue as a molecular probe shows the importance of the chemical modification of the substrate in the enhancement of the SERS signal.

Keywords:
block copolymer; nanolithography; polystyrene-b-poly(2-vinylpyridine); SERS; silver nanoparticle