2 research outputs found
Organosilicon Coatings Deposited in Atmospheric Pressure Townsend Discharge for Gas Barrier Purpose: Effect of Substrate Temperature on Structure and Properties
Organosilicon plasma polymer and silicalike layers are
deposited
at different temperatures in a dielectric barrier discharge at atmospheric
pressure operating in the Townsend regime. Final properties of these
two kinds of layers can be finely tuned by the plasma process conditions.
In particular, influence of deposition temperature is investigated
when hexamethyldisiloxane based monolayers are deposited on poly(ethylene
naphtalate) substrate. Coating chemical structure is tested by means
of Fourier transform infrared spectroscopy and X-ray photoelectron
spectroscopy. Their thickness, topography, and mechanical properties
are evaluated by ellipsometry, scanning electron microscopy observation
of coatings cross sections, atomic force microscopy, and nanoscratch
testing. Permeability of coated polymer is measured for transparent
silicalike layers, and the effect of coating structure on the oxygen
gas permeability is discussed. The deposition temperature of coatings
at 90 °C provides a strong improvement in barrier property compared
to room temperature deposition, thanks to a densification of the SiO<sub>2</sub> matrix and to a decrease in the silanol group content
Laser Ablation of Silver in Liquid Organic Monomer: Influence of Experimental Parameters on the Synthesized Silver Nanoparticles/Graphite Colloids
During the past decade, synthesizing
silver nanoparticles (Ag NPs)
by liquid phase-pulsed laser ablation (LP-PLA) has attracted a lot
of attention. Basically, this technique allows producing various metallic
nanoparticles with controlled size, shape, composition, or surroundings
in several liquids (i.e., water, ethanol, acetone, toluene, and so
forth). Recently, such processes have been studied in liquid organic
monomer such as methyl methacrylate (MMA). However, the influence
of the laser parameters on the materials synthesized in such reactive
liquid and their features were not fully investigated so far. Here
we investigate the LP-PLA of silver in two different but rather similar
acrylate monomers: dodecyl acrylate (DOCA) and 1H,1H,2H,2H perfluorodecyl
acrylate (PFDA). The influence of the fluence and the number of pulses
on the production, size, and morphology of the materials has been
examined. First, factorial design experiments have been achieved in
order to determine the weight of the laser parameters in each precursor.
This study shows two highly different behaviors in function of the
monomer where the process took place. This has been explained by the
plasma plume confinement and/or the “interpulses” self-absorption
of the particles by the laser beam. The formation of graphite around
the synthesized AgNPs has been highlighted by Raman spectroscopy at
low number of pulses. Nevertheless, increasing the number of pulses
could lead to three phenomenon depending on the fluence and the used
monomer: degradation of the matrix, conservation of the matrix with
changes in AgNPs size and distribution, or sustainment of the matrix
with any changes in the particles properties. So the surrounding,
the size, and stability could be triggered by adjusting these parameters.
This paper does highlight that LP-PLA is a powerful technique to provide
AgNPs in acrylate monomer with a good control of their features