Self-assembled monolayers (SAMs) of alkoxycyanobiphenyl thiols on gold surface using a lyotropic liquid crystalline medium

Protection of nickel by self-assembled monolayers prepared in an aqueous self-emulsifying solution of a novel amphipathic organothiol

This report explored a novel amphiphilic organothiol and prepared self-assembled monolayers (SAMs) on Ni substance in the aqueous micellar solution of this amphiphilic organothiol. The as-prepared amphiphilic organothiol can self-emulsify and disperse in an aqueous solution to form a stable emulsion without any additional emulsifier. The experiment shows that the self-emulsifying solution remains stable after six months at room temperature. The resulting SAMs are characterized by electrochemical measurements, XPS, porosity tests, and neutral salt spray experiments. XPS results show that the as-prepared self-emulsifying organothiol can bond to the Ni surface by forming strong thiolate Ni-S bonds. The electrochemical measurements show that the inhibition efficiency (η) and surface coverage (θ) increase with the immersion time in the aqueous micellar solution, reaching the maximum value of about 90 min. Experiments prove that AGE-CA SAMs provided better protection for Ni substances and electroplated Ni film than the OT SAMs from the ethanol solution.

Liquid crystal (LC) monolayer on Indium Tin Oxide (ITO): structural and electrochemical characterization

Superior quality, stable monolayers of LC compounds on ITO substrates are found to be very effective in orienting bulk LC samples.

Controlling liquid crystal alignment using photocleavable cyanobiphenyl self-assembled monolayers

We report on the development of novel cyano-biphenyl-based thiolate self-assembled monolayers designed to promote homeotropic alignment of calamitic liquid crystals. The molecules developed contain an ortho-nitrobenzyl protected carboxylic acid group that on irradiation by soft UV (365 nm) is cleaved to yield carboxylic acid groups exposed at the surface that promote planar alignment. Using a combination of wetting, X-ray photoelectron spectroscopy, Fourier transform-infrared reflection absorption spectroscopy, and ellipsometry we show that high photolysis yields (>90%) can be achieved and that the patterned SAMs are suitable for the controlled alignment of calamitic liquid crystals. This study further shows that such photo-patterned SAMs can be used to control the formation of focal conic domains (FCDs) in the smectic-A phase in terms of positioning and size confinement on surfaces.

Formation of a 1,8-octanedithiol self-assembled monolayer on Au(111) prepared in a lyotropic liquid-crystalline medium

A characterization of the 1,8-octanedithiol (ODT) self-assembled monolayer (SAM) formed from a Triton X-100 lyotropic medium has been conducted by electrochemical techniques. It is found that an ODT layer of standing-up molecules is obtained at short modification time without removing oxygen from the medium. The electrochemical study shows that the ODT layer formed after 15 min of modification time has similar electron-transfer blocking properties to the layers formed from organic solvents at much longer modification times. On the basis of XPS data, it is demonstrated that the inability to bind gold nanoparticles (AuNPs) is due to the presence of extra ODT molecules either interdigited or on top of the layer. Treatment consisting of an acid washing step following the formation of the ODT-Au(111) SAM produces a layer that is able to attach AuNPs as demonstrated by electrochemical techniques and atomic force microscopy (AFM) images.