Selective decoration of a phase-separated diblock copolymer with thiol-passivated gold nanocrystals

Nanocrystalline gold particles passivated with alkane- and arenethiols were deposited on microphase-separated ultrathin films of poly(styrene-block-methyl methacrylate). The nanocrystals preferentially adsorbed to the polystyrene phases over areas of the substrate as large as 10 mu m(2), as seen by transmission electron microscopy. The basis for the separation is postulated to be the difference in interaction energies between the thiol passivants and the two polymers. The resulting patterns of nanocrystals are more than an order of magnitude smaller than features which can be produced by optical lithography.