Modification of Aliphatic Self-Assembled Monolayers by Free-Radical-Dominant Plasma:  The Role of the Plasma Composition

Abstract

Modification of octadecanethiolate self-assembled monolayers on Au by nitrogen-oxygen or argon-oxygen downstream microwave plasma with a low oxygen content (estimated below several percent) has been studied by synchrotron-based high-resolution X-ray photoelectron spectroscopy and water contact angle measurements. For both types of plasma, the primary processes were found to be the loss of conformational and orientational order and the oxidation of the alkyl matrix and headgroup-substrate interface. At the same time, the film modification occurred much faster and with different intermediates for the nitrogen plasma than for the argon plasma. The reasons for these differences are considered in terms of the different reactivities and different efficiencies of the energy transfer between the plasma constituents in these two types of plasma.

Application of Plasma Immersion Ion Implantation for Surface Modification of Nickel-titanium Rotary Instruments

“…The presence of TiO2 resulted from the presence of residual oxygen in the reactive chamber. In addition, minor oxygen species in the ionic or free radical state are recognized as highly reactive species, and the composition of reactive species in non-oxygen plasma may have an effect on the surface properties of a thin PIII-treated layer 25) . As for nitrogen, it is the most common atom in NiTi alloys and stainless steel to enhance their mechanical properties and corrosion resistance 26,27) .…”

Quartz crystal microbalance in clinical application

“…In Figure 1, the image of the topographical map taken in the semi-contact mode of a 10×10 μm 2 zone is shown. Figure 1 Most SAMs studies were established on the ideal, well-ordered and smooth single-crystal silicon (100 or 111) wafers primed with a metal adhesion layer (Weng et al, 2004(Weng et al, , 2006. On the single-crystal silicon wafers, theoretically, all alkanethiols should be bound onto the SAMs surface as an Au-S-C-structure.…”

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

“…Presumably, only a small fraction of electrons and ionized species survives during the transport to the afterglow region. However, there is still a noticeable portion of long-living free radicals [6][7][8], which can become the dominant reactive species in the afterglow region.…”

“…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.…”