Single-crystalline gold nanoplates with a thick- ness of less than 100 nm were synthesized by the reduction of HAuCl4 in water with cetyltrimethylammonium chloride, and their structures were confirmed by scanning electron microscopy, transmission electron microscopy, and X-ray diffraction measurements. The formation and surface structures of octanethiol (OT) self-assembled monolayers (SAMs) on gold nanoplates were examined by means of atomic force microscopy and scanning tunnelling microscopy (STM). Molecularly resolved STM observation showed that OT SAMs on gold nanoplates at 25 °C for 24 h were composed of two mixed phases containing well-ordered (√3 × √3)R30° and c(4 × 2) domains and disordered domains, which are comparable to the formation of fully covered (√3 × √3)R30° or c(4 × 2) structures on conventional Au(111) films. After thermal annealing of the precovered OT SAMs on gold nanoplates at 70 °C for 30 min, we clearly observed the structural transitions of OT SAMs from the two mixed phases to the loosely packed, uniform 6 × √3 phase, which is mainly driven by the optimization of van der Waals interactions between alkyl chains via the rearrangement of OT molecules in the two mixed domains to reach thermodynamically stable SAMs. Our results herein provide new insights into the formation and structural behaviors of alkanethiol SAMs on size-confined gold nanostructures.

Superhydrophobic membranes with high gas permeability were prepared and characterized. Materials such as a metal mesh, paper, fabric and polytetrafluoroethylene were dip-coated in a hexane-based solution of SiO 2 nanoparticles coated with polydimethylsiloxane (PDMS). The dip-coating provided a superhydrophobic characteristic to the surfaces of our membranes with water contact angles exceeding 160 . On the other hand, a high membrane permeability of CO 2 and dimethyl methylphosphonate vapor were obtained, indicating that our preparation method is useful for the fabrication of gas sensor shielding layers that allow selective permeation of gas vapors from gas/aqueous-liquids mixtures. Fig. 1 Schematic diagram of the experimental set-up for (a) the preparation of hydrophobic coating on silica nanoparticles, and (b) the preparation of dip-coating solution and superhydrophobic films. 40596 | RSC Adv., 2015, 5, 40595-40602 This journal is

No abstract