The Effect of the Substrate on Response of Thioaromatic Self-Assembled Monolayers to Free Radical-Dominant Plasma

Abstract

Synchrotron-based high-resolution photoelectron spectroscopy was applied to study the modification of self-assembled monolayers (SAMs) of 4‘-methyl-1,1‘-biphenyl-4-thiols (BPT) on (111) gold and silver substrates by a nitrogen−oxygen downstream microwave plasma and the attachment of acrylic acid to the plasma-modified SAMs. The plasma treatment resulted in massive damage and disordering of the BPT films, with the extent and character being noticeably different for BPT/Au and BPT/Ag. Whereas for BPT/Au a profound desorption of the entire BPT moieties and a complete defragmentation of the residual hydrocarbon part occurred, only partial desorption and oxidation took place for BPT/Ag, where even a part of intact BPT moieties survived the plasma treatment. The differences in the response of BPT/Au and BPT/Ag to the plasma treatment are related to the stronger thiolate−substrate bonds for the latter system. Taking into account that an analogous difference was also observed in alkanethiolate films, one can consider it as a general property of thiol-derived SAMs. The extent of acrylic acid attachment to the plasma-treated BPT/Ag was found to be essentially larger than that to the hydrocarbon residues in the case of BPT/Au.

Improved surfaced-enhanced Raman scattering based on electrochemically roughened silver substrates modified through argon plasma treatment

“…The enhancement was strongly correlated with the degree of coalescence of the initially present Ag grains (10-50 nm in size), which led to the formation of 100-300-nm Ag hills in which each Ag grain remained clearly distinguishable. A series of recent publications has dealt with the interaction of different plasmas with selfassembled monolayers (SAMs) [7,[28][29][30][31][32][33][34][35][36]. Terfort and co-workers [37] explored the plasma treatment of SAM-coated gold surfaces with either hydrogen or oxygen plasma, using X-ray photoelectron spectroscopy (XPS), scanning tunneling microscopy (STM), ellipsometry, and contact angle measurements for surface characterization.…”

Perspective on the Development of Microplasma Technology: The Role of Oxygen in Downstream Microwave Plasma

“…In the case of low-pressure plasma processing of a target object, ions and free radicals are known to be of major importance, mediating reactive chemistry at the plasma-object interface [1][2][3]. However, other active agents associated with plasma such as, e.g., electrons of different kinetic energies and photons of varied wavelengths can still be of importance.…”

“…In our previous studies, we have shown that low-density (∼ 10 6 particles/cm 3 ) downstream plasma can be successfully used to modify ultra-thin organic films, such as, e.g., aliphatic and aromatic thiol-derived selfassembled monolayers (SAMs) [1,2,7,8]. There are several major processes, which occur both simultaneously and subsequently during the exposure of SAMs to the plasma.…”

“…All these processes result in chemical modification and partial or even complete desorption of the monomolecular film, which can be, e.g., used for its patterning. [1,2,[7][8][9][10]. Particular techniques based on weakly-ionized micro-plasma [11,12] and/or micro-plasma jet at atmospheric pressure [13] are also well suited for advanced treatment of sensitive objects.…”

Hydrophilic Treatment of the Dyed Nylon-6 Fabric using High-density and Extensible Antenna-coupling Microwave Plasma System

“…Laboratory study using 95% N 2 and 5% vaporized acrylic acid (AAc) to graft copolymerization with a plasma-treated organic layer has exhibited successfully. Such combined procedure is conducted in a dry and low-vacuum system, (22) which is seeking for a consistence with the factory-oriented process. Yet, the grafting density using the above-mentioned method is rapidly saturated as a function of time owing to the recombination of binding sites on the plasma-treated surface.…”