Abstract:Understanding the polymerization mechanism of a precursor is indispensable to enhance the requisite material properties. In situ mass spectroscopy and X‐ray photoelectron spectroscopy is used in this study to understand the RF plasma polymerization of γ‐terpinene. High‐resolution mass spectra positive ion mass spectrometry data of the plasma phase demonstrates the presence of oligomeric species of the type [M+H]+ and [2M+H]+, where M represents a unit of the starting material. In addition, there is abundant fr… Show more
“…The reduction in E g as a result of power deposition was attributed to dangling bonds that formed in the polymer structure during the fabrication process. At low input power density, a low concentration of dangling bonds are created due to their saturation with hydrogen atoms, whereas higher input power enhances the fragmentation rate in the plasma field [41], which highly accelerates the formation of chains with unsaturated bonds [42]. The relatively high energy gap for geranium plasma polymer films is in good agreement with the low conductivity values acquired in this study.…”
Abstract:Inherently volatile at atmospheric pressure and room temperature, plant-derived precursors present an interesting human-health-friendly precursor for the chemical vapour deposition of thin films. The electrical properties of films derived from Pelargonium graveolens (geranium) were investigated in metal-insulator-metal (MIM) structures. Thin polymer-like films were deposited using plasma-enhanced synthesis under various plasma input power. The J-V characteristics of thus-fabricated MIM were then studied in order to determine the direct current (DC) conduction mechanism of the plasma polymer layers. It was found that the capacitance of the plasma-deposited films decreases at low frequencies (C ≈ 10 −11 ) and remains at a relatively constant value (C ≈ 10 −10 ) at high frequencies. These films also have a low dielectric constant across a wide range of frequencies that decreases as the input RF power increases. The conductivity was determined to be around 10 −16 -10 −17 Ω −1 m −1 , which is typical for insulating materials. The Richardson-Schottky mechanism might dominate charge transport in the higher field region for geranium thin films.
“…The reduction in E g as a result of power deposition was attributed to dangling bonds that formed in the polymer structure during the fabrication process. At low input power density, a low concentration of dangling bonds are created due to their saturation with hydrogen atoms, whereas higher input power enhances the fragmentation rate in the plasma field [41], which highly accelerates the formation of chains with unsaturated bonds [42]. The relatively high energy gap for geranium plasma polymer films is in good agreement with the low conductivity values acquired in this study.…”
Abstract:Inherently volatile at atmospheric pressure and room temperature, plant-derived precursors present an interesting human-health-friendly precursor for the chemical vapour deposition of thin films. The electrical properties of films derived from Pelargonium graveolens (geranium) were investigated in metal-insulator-metal (MIM) structures. Thin polymer-like films were deposited using plasma-enhanced synthesis under various plasma input power. The J-V characteristics of thus-fabricated MIM were then studied in order to determine the direct current (DC) conduction mechanism of the plasma polymer layers. It was found that the capacitance of the plasma-deposited films decreases at low frequencies (C ≈ 10 −11 ) and remains at a relatively constant value (C ≈ 10 −10 ) at high frequencies. These films also have a low dielectric constant across a wide range of frequencies that decreases as the input RF power increases. The conductivity was determined to be around 10 −16 -10 −17 Ω −1 m −1 , which is typical for insulating materials. The Richardson-Schottky mechanism might dominate charge transport in the higher field region for geranium thin films.
“…3(a) displays the presence of strong carbon and oxygen at peaks at 282 and 531 eV, respectively. The C 1 s peaks for geranium polymers were fitted with four peaks, which can be ascribed to major hydrocarbon C–C/C–H (BE = 284.9 eV), and other functional groups, such as ether C–O (BE = 286.2 eV), carbonyl C = O (BE = 287.5 eV), and ester O–C = O (BE = 288.9 eV) 29 , as seen in Fig. 3(c).Figure 3Full scan XPS spectrum of pristine polymer ( a ) and composite ( b ) thin films.…”
Nanocomposites offer attractive and cost-effective thin layers with superior properties for antimicrobial, drug delivery and microelectronic applications. This work reports single-step plasma-enabled synthesis of polymer/zinc nanocomposite thin films via co-deposition of renewable geranium essential oil-derived polymer and zinc nanoparticles produced by thermal decomposition of zinc acetylacetonate. The chemical composition, surfaces characteristics and antimicrobial performance of the designed nanocomposite were systematically investigated. XPS survey proved the presence of ZnO in the matrix of formed polymers at 10 W and 50 W. SEM images verified that the average size of a ZnO nanoparticle slightly increased with an increase in the power of deposition, from approximately 60 nm at 10 W to approximately 80 nm at 50 W. Confocal scanning laser microscopy images showed that viability of
S. aureus
and
E.coli
cells significantly reduced on surfaces of ZnO/polymer composites compared to pristine polymers. SEM observations further demonstrated that bacterial cells incubated on Zn/Ge 10 W and Zn/Ge 50 W had deteriorated cell walls, compared to pristine polymers and glass control. The release of ZnO nanoparticles from the composite thin films was confirmed using ICP measurements, and can be further controlled by coating the film with a thin polymeric layer. These eco-friendly nanocomposite films could be employed as encapsulation coatings to protect relevant surfaces of medical devices from microbial adhesion and colonization.
“…The reduction in the peak intensities and disappearance of some peaks in the polymer can be interpreted as the precursor molecules being partially dissociated as a result of being subjected to the RF plasma field [ 33 ]. However, the absorption band of C=O asymmetric stretching observed in the 1800−1600 cm −1 region was possibly due to the post oxidation of the trapped free radicals, confined during film formation [ 34 ].…”
Bacterial colonisation of biomedical devices demands novel antibacterial coatings. Plasma-enabled treatment is an established technique for selective modification of physicochemical characteristics of the surface and deposition of polymer thin films. We investigated the retention of inherent antibacterial activity in geranium based plasma polymer thin films. Attachment and biofilm formation by Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli was significantly reduced on the surfaces of samples fabricated at 10 W radio frequency (RF) power, compared to that of control or films fabricated at higher input power. This was attributed to lower contact angle and retention of original chemical functionality in the polymer films fabricated under low input power conditions. The topography of all surfaces was uniform and smooth, with surface roughness of 0.18 and 0.69 nm for films fabricated at 10 W and 100 W, respectively. Hardness and elastic modules of films increased with input power. Independent of input power, films were optically transparent within the visible wavelength range, with the main absorption at ~290 nm and optical band gap of ~3.6 eV. These results suggest that geranium extract-derived polymers may potentially be used as antibacterial coatings for contact lenses.
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