Nanostructures fabrication via self-assembly of hybrid block copolymer/nanoparticles in thin film

Hierarchical nanostructure of gold nanoparticles via self-assembled block copolymer have been investigated on native oxide-terminated Si(111). Au-nanoparticles were prepared via simple wet chemical method by using Poly styrene-block-4-vinylpyridin (PS-b-P4VP) as stabiliser in nonaqueous solvents. Transmission Electron Microscopy (TEM) is used to characterise the size of the Aunanoparticles. However, the size distribution of Aunanoparticles is found to be narrowly dispersed with dimension of 2-3 nm. Adsorption (via spin-coating) on hydrophilic surfaces results a necklace-like structure. Adding a nonpolar selective solvent (toluene) to one of the block copolymer leads to the formation of nanoporous morphology with two different diameters. Tapping Mode Atomic Force Microscopy (TMAFM) measurements on spin-coated thin film observed large holes (120 nm in diameter) surrounded with small porous ones with an average diameter of 25 nm. Solvent-evaporation from the surface to the interface with the substrate and dewetting of the block copolymer chains on substrate were found to be of great significance in the fabrication of the two different sizes of the nanoporous.