Nanoelectrochemical Patterning of Monolayer Surfaces: Toward Spatially Defined Self-Assembly of Nanostructures

Abstract

cent reaction conditions. The mass yield is assigned as m(t)/m(¥) The data are fitted into the three-parameter Avrami equation (see text, Eq. 1) using Microcal Origin 4.1 software package on a PC-compatible computer.AFM experiments were performed using a Digital Instruments Nano-Scope III with a phase-extender module, operating in tapping mode. Samples were prepared on a graphite substrate by placing the substrate (for a few seconds) in the synthesis solution with a reactant mole ratio of 100 H 2 O : x HCl : 0.11 CTACl : 0.13 TEOS (for fiber, x = 7; for gyroid, x = 3.5), with subsequent gentle washing in distilled water. The A+B feedback signal was~3 V, whereas the root mean square (rms) signal was set at 0.3 V. Feedback gain parameters were set between 1 and 2 for both integral and proportional gains. UltraSharp NT-MDT silicon cantilevers SCS11 (resonance frequency is 300±380 kHz) were used throughout the study. The drive amplitude was set between 600 and 800 mV, whereas the working frequency was chosen to be~360 kHz. The D scan head (maximum scan area is 12.5´12.5 mm 2 , z-sensitivity is 9 nm/V) was employed throughout the study. Scan rates of~1 Hz were chosen.TEM experiments were performed using a Philips 430 microscope operating at 100 kV with 100 000´magnification. The samples were prepared by dipping a carbon-coated copper TEM grid into the aqueous solution with a mole ratio of 100 H 2 O : x HCl : 0.11 CTACl : 0.13 TEOS (for fiber, x = 7; for gyroid, x = 3.5). The excess solution was then blotted off from the grid and air dried. The white and black amorphous-like regions are probably adventitious surfactant and silicate residues, respectively, that had been incompletely removed from the seed during the blotting step.

Insight into the Structure and Nanoscale Conductivity of Fluorinated Ionomer Membranes

“…Nafion structures have been directly visualized by transmission electron microscopy (TEM), where the nano-sized domains can be directly imaged. 24,25 In dry membranes from 3 M polymers (side chain with medium size), an even distribution of ionic clusters with a size of 2 nm and an inter-cluster distance of 3 nm was found, a value also typical for the other ionomer systems. 26 By partially hydrated cryo-TEM investigation, a swelling of the cluster size was observed until they started to coalesce without changing their distances.…”

Advanced scanning probe lithography

“…Selective oxidation and/or complete removal of selfassembled monolayers and subsequent surface functionalization of the oxidized regions 13 has enabled the fabrication of nanoscale architectures 6,101 . Figure 5d-e illustrates the process to pattern linear arrays of proteins with a size that matches the molecular size of the protein, in this case ferritin.…”

Formation of aldehyde‐ and carboxy‐terminated self‐assembled monolayers on SiO2 surfaces

“…[8,12 -16] These few have been generally prepared through a chemical or physical oxidation of terminal groups, such as cyano, vinyl and methyl groups, using oxidizing reagents, [12 -16] ultraviolet (UV) laser, [8] or atomic force microscopy (AFM). [15] In this study, we report the formation of CHO-and COOHterminated organosilane SAMs on SiO 2 /Si substrates based on the chemisorption of a vapor phase of triethoxysilylundecanal (TESUD) molecules and subsequent photooxidation of the terminal groups using 172-nm vacuum UV light, respectively. Among the various oxidation methods, [8,12 -16] we employed a photooxidation technique using 172-nm vacuum UV light, since conventional chemical oxidation employing oxidizing reagents sometimes causes severe damage to the sample surface and generally requires a relatively long treatment time, [12 -16] which greatly depends on the oxidation conditions.…”